TCVN 9258:2012 Heat protection for residential buildings – Design guide
Foreword
TCVN 9258:2012 was converted from TCXDVN 293:2003 in accordance with the provisions of Clause 1, Article 69 of the Law on Standards and Technical Regulations and Point b), Clause 1, Article 7 of the Government’s Decree No. 127/2007/ND-CP dated August 1, 2007, detailing the implementation of some articles of the Law on Standards and Technical Regulations.
TCVN 9258:2012 was compiled by the Institute of Architecture, Urban and Rural Planning – Ministry of Construction, proposed by the Ministry of Construction, appraised by the Directorate for Standards, Metrology and Quality, and promulgated by the Ministry of Science and Technology.
1. Scope
This standard is applied to the design of thermal insulation for residential buildings when constructing new or renovating.
This standard does not apply to temporary constructions, camps, construction sites, underground works, special works, etc.
2. Referenced documents
The following referenced documents are indispensable for the application of this standard. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
TCVN 4605:1988, Thermal engineering – Building envelopes – Design standard;
TCVN 5687:2010, Ventilation – Air conditioning – Design standard;
TCVN 5718:1993, Reinforced concrete roofs and floors in construction works – Technical requirements for waterproofing;
TCXD 230:19981), Foundations for anti-humidity – Design and construction standards;
TCXD 232:19991), Ventilation, air conditioning and refrigeration systems – Fabrication, installation and acceptance;
TCXDVN 306:20041), Residential and public buildings – Indoor microclimate parameters – Terms and definitions.
3. Terms and definitions
3.1. Amplitude of temperature fluctuation At[°C]
The absolute value of the difference between the highest (or lowest) temperature value and the average day-night temperature when the temperature fluctuation exhibits periodicity.
3.2. Thermal inertia D
Indicates the degree of quick or slow increase or decrease of temperature fluctuation inside the building envelope when subjected to fluctuating heat flow. For building envelopes made of homogeneous materials, D = RS; for multi-layer building envelopes D = ΣRS. Where R is the thermal resistance, S is the heat storage coefficient of the material. The larger the D value, the faster the temperature fluctuation attenuates, the better the thermal stability of the building envelope.
3.3. Thermal stability
The ability to resist temperature fluctuations of the building envelope under the influence of periodic heat. The thermal resistance of the building envelope mainly affects the thermal stability. The thermal stability of a room is the ability to resist temperature fluctuations of the entire room under the influence of periodic indoor and outdoor heat. The thermal stability of a room is determined by the stability of the building envelope.
3.4. Window-to-wall ratio
The ratio of window area to the area of the surrounding walls of the room (also known as the area enclosed by the floor height of the room and the room location line).
3.5. Attenuation factor V0 and time lag S0 (h)
Building envelopes under the influence of combined temperature fluctuations. Temperature fluctuations gradually decrease with thickness, with smaller and smaller daily fluctuation amplitudes. The ratio of the combined outdoor temperature fluctuation amplitude to the indoor surface temperature fluctuation amplitude, A0i is called the amplitude reduction factor, i.e. n0 = At.sa/A0i. The difference between the time of occurrence of the highest indoor surface temperature t2 and the time of occurrence of the largest combined outdoor temperature value t1, is called the time lag, also known as S0 = t2 -t1.
3.6. Water vapor permeability coefficient
The amount of water vapor permeating through a unit area in a unit time with an object 1 m thick and a water vapor pressure difference of 1 Pa on both sides.
3.7. Water vapor permeation resistance
The reciprocal of the water vapor permeability coefficient.
3.8. Surface condensation
The phenomenon when the surface temperature of an object is lower than the dew point temperature of the surrounding air, condensation will appear on the surface.
3.9. Number of heating days Z (d)
The number of days with an average daily temperature over many years less than or equal to 10°C.
4. General provisions
4.1. When designing thermal insulation for residential buildings, it is necessary to determine the comfort zone for humans in different activity states. The comfort zone refers to Appendices A, B and C of TCVN 5687:2010 or the microclimate parameters specified in TCXDVN 306:2004.
4.2. The outdoor climate calculation parameters are taken according to the natural condition data used in construction [1].
4.3. When calculating thermal insulation for residential buildings using air conditioning equipment and other heating and cooling equipment, it is necessary to consider hygiene and physiological health indicators with the indoor air temperature ensured at 25°C.
4.4. When designing residential buildings, architectural and building physics solutions should be used to design building envelopes in order to retain heat, avoid cold winds in winter; ensure ventilation, take advantage of natural ventilation, cross ventilation in summer, combined with the use of table fans, ceiling fans, etc. as prescribed in TCVN 4605:1988.
4.5. In case of using technical measures of ventilation – air conditioning, it is necessary to comply with the provisions of TCVN 5687:2010.
4.6. In case natural ventilation cannot ensure the microclimate comfort conditions, it is necessary to increase the air movement speed to maintain the thermal sensation index within the allowable range. When the indoor temperature increases by 1°C, the wind speed should be increased from 0.5 m/s to 1.0 m/s.
4.7. The upper limit corresponding to the body’s tolerance is calculated with a temperature of t = 29.5°C, humidity φ = 80%
4.8. When designing a thermal insulation system placed on a sliding foundation, it is necessary to have a solution to prevent the foundation soil under the construction from getting wet by drainage measures in underground ditches, underground pits as well as other water accumulation points.
4.9. When designing residential buildings, it is necessary to calculate the microclimate factors to ensure that the indoor humidity does not exceed the allowable relative humidity limit [_φ_max]. It is necessary to have ventilation solutions, opening and closing doors at appropriate times in weather conditions with high outdoor air humidity. The calculation of anti-humidity and anti-condensation for building foundations must comply with the provisions of TCXD 230:1998.
5. Determining outdoor climate calculation parameters
The determination of outdoor climate calculation parameters needs to follow the provisions of TCVN 5687: 2010
6. General requirements for thermal insulation design
6.1. General requirements
6.1.1. Summer thermal insulation should use comprehensive measures such as shading and thermal insulation of building envelopes, planting trees, natural ventilation (see Appendix D).
6.1.2. The building façades facing East – West should have the smallest surface area to limit solar radiation. If it cannot be arranged, it can be arranged in another direction, but it must be ensured: directly or indirectly receiving the prevailing winds in summer and avoiding cold winds in winter. Shading design solutions need to be checked and evaluated according to the apparent motion diagram of the sun.
NOTE: In special cases, it is allowed to arrange the building façade deviating from the East – West axis by an angle α from 10° to 15°.
6.1.3. Priority should be given to directly receiving wind, minimizing apartments without wind. In case the apartment is not directly ventilated, there must be a solution to indirectly receive wind and cross ventilation should be implemented (see Article 8).
6.1.4. When planting trees, it is necessary to choose deciduous trees in winter (to take advantage of heating and lighting sunlight for the house) and with many leaves in summer (to shade). Around the house, it is necessary to arrange suitable grass – green tree mats to reduce the ground surfaces, roads with high heat radiation and accumulation coefficients.
NOTE:
1) When planting trees, it is necessary to arrange: tall trees in the shading directions in summer: West, Southwest;
2) When the house does not directly receive wind, bushes can be planted as hedges or low walls can be built protruding at the end of the wind inlet to increase the positive wind pressure zone. On the leeward side, it is necessary to build a low wall to create a wind flow from the positive pressure zone to the negative pressure zone through the living rooms (see Figure E3 Appendix E);
3) Bushes planted in the directions that need to take light must ensure the distance from the house to avoid blocking the wind from the East, Southeast directions in summer or planting the layers of tall trees and bushes appropriately;
4) In hilly and sloping areas, it is necessary to plant wind-shielding trees in winter (North direction). On the hillsides, it is necessary to plant trees that both shield the wind and rain, avoid concentrated water erosion at the base of the house walls.
6.1.5. When arranging windows and doors, it is necessary to arrange them in the most favorable way for natural ventilation and limit the main living rooms from being exposed to the East – West sun (see Figures E.4 to E.13 – Appendix E). Window sills should not be higher than 0.6 m from the floor level to take advantage of summer ventilation.
6.1.6. Rooms facing East – West should have balconies, loggias, corridors, overhangs to shade or use fixed or movable shading solutions (see Appendix D).
6.1.7. Walls and roofs on the East – West and West – South directions must be designed with thermal insulation or shading to reduce direct solar radiation. For high-end residential buildings, walls and roofs must be insulated in all directions in summer and winter (see Appendix F).
The indoor surface temperature of the roof ceiling and exterior walls facing East – West – South must be checked to ensure the thermal comfort conditions prescribed in TCXDVN 306: 2004.
6.1.8. To prevent heat, it is not advisable to design many glass windows, especially on the West and East walls. If it is mandatory to use them, reflective glass or low-E glass should be used.
NOTE: Low-E glass is a type of glass with the property of slow heat emission, reducing heat dissipation, slow heat absorption and slowing down the heat transfer process.
6.1.9. To prevent water condensation on the floor (when the surface temperature of the object is lower than the dew point temperature of the surrounding air), the ground floor (1st floor) should use a hollow floor. The floor finish layer should use moisture-absorbing materials.
6.1.10. To reduce the psychological feeling of hot – cold in the room, it is necessary to appropriately use materials corresponding to colors, with a surface thermal reflectance suitable for color perception.
6.1.11. The outer surface of the building should use light colors, with a low solar radiation heat absorption coefficient to minimize the heat load acting on the house walls in summer.
6.1.12. For flat roofs or sloped roofs, it is necessary to have solutions to use appropriate roofing sheets and ceilings to reduce heat transmission into the house such as:
– Use closed or ventilated ceilings (see Figures E7, E8, E13 in Appendix E);
– Ensure ventilation of the attic space (if any), roof;
– Ceiling panels with a high thermal reflectance on the top surface of the ceiling and the bottom surface of the roof should be used (see Figure E13 in Appendix E and refer to the roof types in Appendix F);
– Use some lightweight, quick-drying, waterproof, good thermal insulation and moisture-proof materials in accordance with TCVN 5718:1993;
– The entire roof should use lightweight materials that cool quickly thanks to natural wind.
6.1.13. There should be a courtyard or a part or the entire first floor can be left open to receive wind, increase cross ventilation, prevent moisture for the first floor and ventilate the disadvantaged rooms at the back.
6.1.14. For high-rise residential buildings, it is necessary to arrange empty floors or service floors halfway up with buildings over 10 floors to plant trees and create ventilation (see Figure E12 Appendix E).
6.1.15. For low-rise residential buildings (not exceeding 3 floors), there should be an inner courtyard with green trees to create a good microclimate and natural ventilation.
6.1.16. It is necessary to select the types of green plants that have the ability to absorb a lot of toxic gases and other toxic substances inside and outside the house to both create a landscape and purify the indoor and outdoor air environment.
NOTE: Refer to Appendix K to select the appropriate indoor and outdoor plant species.
6.2. Determining the building orientation in the overall planning
6.2.1. The selection of the building orientation needs to comply with the planning regulations [2] while minimizing solar radiation on the building surfaces and direct radiation into the rooms through the windows in summer;
6.2.2. The organization of the overall architectural layout must ensure the provisions on the distance between buildings as follows:
a) Buildings arranged in parallel: L = from 1.5 H to 2 H when the wind blows perpendicular to the building façade;
L = 1 H when the wind angle to the building façade is α = 45°;
Where:
L: distance between buildings.
H: building height
b) It is necessary to combine the factors of outdoor and indoor space combination with natural environmental factors according to the concept of “open architecture” to improve indoor and outdoor microclimate comfort, in order to achieve human thermal comfort conditions.
6.2.3. Natural ventilation for residential buildings in hot and humid climates depends on the local solution as follows:
a) Building orientation, building shape, interior layout, size ratio, position and area of window openings;
b) If the prevailing wind direction and the building orientation chosen to avoid solar radiation do not coincide, in this case, a balance must be made between the two factors of solar radiation and wind direction:
– Priority should be given to receiving natural wind when residential buildings use natural microclimate;
– Priority should be given to avoiding sunlight when residential buildings use artificial microclimate;
– The solar radiation factor is solved by solutions: shading, architecture, green trees, thermal insulation for walls and roofs in the directions of large solar radiation to reduce direct radiation.
6.2.4. In coastal areas, the building orientation facing the sea can be chosen to receive cool breezes, and in areas with westerly winds (hot and dry), the building orientation can be East – West or the terrain changes the wind direction, it is necessary to flexibly choose the favorable direction for receiving natural wind.
6.2.5. Auxiliary buildings, auxiliary roofs, climbing plants on walls or plant trellises can be used to shade.
6.2.6. Directional shields can be used to change the wind flow that is beneficial for the ventilation of the living rooms.
6.3. Design requirements when residential buildings use air conditioning
6.3.1. When designing residential buildings, it is necessary to thoroughly use heat prevention solutions by natural microclimate adjustment solutions, while calculating and checking the indoor heat and humidity conditions to suit the human comfort zone in the locality. When exceeding the scope of natural microclimate adjustment, there must be other solutions along with air conditioning during peak hot periods.
When designing residential buildings using air conditioning, it is necessary to comply with the provisions of TCVN 5687: 2010 and relevant current standards.
6.3.2. The window area should not be larger than 50% of the floor area, have tightness and allowable thermal insulation. Windows facing West – East – South need to have shading solutions. Screens, curtains, blinds should be used to partially shade direct sunlight. Glass shutters can be opened and closed to suit the seasons. Doors must have large overhangs, shielding from rain and sun, and when needed, breathable blinds can be hung.
Limit direct radiation from outside the room to minimize direct radiation into the room, wasting energy for summer cooling.
The allowable indoor temperature fluctuation range in non-air-conditioned rooms is from 1°C to 5°C.
6.3.3. The heat transfer coefficient of the building envelope is determined after comparing the technical and economic solutions.
6.3.4. To avoid disadvantages to human health due to sudden temperature changes, it is necessary to pay attention to:
a) When designing, it is advisable to create transitional spaces from outside to the living room;
FOR EXAMPLE: Side corridors, front rooms should be designed as buffer spaces (see Figure 1).
b) Smoking is not allowed in air-conditioned living rooms;
c) Additional negative ion generating devices should be installed to increase the negative ion concentration in the room;
d) Use air disinfectants (non-toxic to humans).
7. Designing shading and shadow structures
7.1. Shading and shadow structures
7.1.1. When designing shading and shadow, the following requirements must be ensured:
– In all cases, it is necessary to shade and create shadows from the outside of the door without letting the sun in and then shading;
– Meet the shading requirements during the hours when the direct radiation on the wall and roof surfaces is greatest in the locality;
– Ensure the allowable summer shading hours according to the local time and location. Anti-glare, anti-dazzle from direct and diffused radiation;
– Ensure the requirements of rain shielding, anti-splashing rain, driving rain when there is an average wind speed. Avoid north winds and receive cool summer winds;
– Do not obstruct natural ventilation;
– Ensure the requirements of natural lighting;
– Meet aesthetic needs with the combination of flexible shading forms: curtains, blinds, movable blinds made of alloys, synthetic plastics, etc.
Figure 1 – Transitional space for both natural and artificial microclimate conditions
7.1.2. When designing shading, it is advisable to establish shading charts for each climatic zone as a basis for calculating and evaluating design solutions.
7.1.3. It is necessary to organize anti-glare and shading for transparent building envelopes (glass types).
7.1.4. When designing shading, pay attention to the following factors when calculating:
a) Shading solutions, combined with requirements: thermal insulation, rain shielding, anti-glare, anti-dazzle, ventilation, artificial lighting and architectural shaping;
b) Choose the form, type, size, on the basis of comparing the economic problem according to the type and grade of the project and investment capital.
7.1.5. To minimize the increase in room temperature due to direct radiation, take the summer indoor design temperature from 27°C to 28°C as the basis for shading design:
NOTE: In Vietnam, the total outdoor air temperature can be taken greater than 27°C when direct solar radiation on the window surface is greater than 230 Kcal/m2h (for people directly exposed to radiation).
7.1.6. To evaluate the effectiveness of horizontal shading, it is necessary to draw a limit line α, divided from 0° (horizon) to 90° (zenith), evenly spaced by 10° (see Figure 2).
Figure 2 – Evaluating the shading effectiveness of horizontal structures
7.1.7. Vertical shading panels (see Figure 3)
To determine the shading and sunlight area of the vertical shading structure, on the sky model, it is necessary to determine two vertical planes, going through the vertical axis at the center of the door and the outer edge of the shading structure defined by the angles βt and βp.
Figure 3 – Evaluating the shading effectiveness of vertical structures
Some charts of shading limit lines and shading solutions of some common structures (see Figures 4 and 5).
NOTES:
1) Open overhang: has a movable shading and sunlight area, depending on the observation point in the room;
2) Open overhangs are suitable for shading the deep parts of the room when the sun is high – then the areas near the window can be exposed to sunlight:
+ The vertical shading area is bounded by the planes containing the window.
+ The vertical sunlight area is the part of the sky between the two β planes.
NOTE: The shading limit line diagrams must be established corresponding to the methods of establishing the sun diagrams and with the same scale. Then they are used to evaluate the shading effectiveness of the structures |
Figure 4 – Diagrams of shading limit lines (according to the perspective projection method)
Figure 5 – Shading solutions of common structures
7.1.8. To evaluate the shading effectiveness, it is necessary to use charts of horizontal and vertical shading limit lines, and at the same time combine with the requirements of natural lighting and rain shielding to select appropriate shading solutions.
7.1.9. The rain shielding angle of horizontal and vertical shading panels is specified in Table 1.
Table 1 – Wind speed, rain falling angle and rain shielding angle of horizontal and vertical shading panels
Wind speed Vg m/s | Rain falling angle β (0) | Rain shielding angle α (0) |
4 | 45 | 45 |
7 | 60 | 30 |
10 | 70 | 20 |
15 | 75 | 15 |
NOTE: Formula for rain shielding angle α: α = arctg (4/Vg) The data in the above table help calculate rain shielding for houses when determining the angle between the horizontal shading panels or the inclined shielding panels above the windows. To ensure rain shielding and lighting – shading, choose a in the range from 20° to 30° (see Figure 6). |
Figure 6 – Rain falling angle (β) and rain shielding angle (α)
7.2. Shading forms
7.2.1. Overhangs: Can be used in one, two, or three tiers, lying horizontally or obliquely.
– Single-tier horizontal overhangs can shade when the sun is in a high position (vertical shading angle β ≤ 30°); used for north-facing doors;
– If it is necessary to shade when the sun is in a low position, (sun altitude angle h ≤ 30°), it is advisable to use oblique overhangs, or combine with front shielding panels (see Appendix D);
– Little impact on natural ventilation and lighting;
– Solid overhangs should have a width not exceeding 60 cm, because when too large, it will affect the microclimate of the area near the window;
– For high rainfall areas, it is necessary to use large overhangs to avoid splashing rain, limit the use of fast louver overhangs;
– From 15° to 8° north latitude, using overhangs in both north and south directions is very good;
– For the east and west directions, as well as the adjacent directions, overhangs only have the effect of shielding rain, anti-glare, not enough to shield direct radiation. It must be combined with other shading methods, it is best to use combined shielding panels as well as movable vertical and horizontal shielding panels (swivel vertically or horizontally) controlled manually or by automatic electric with heat sensing devices.
7.2.2. Fixed vertical panels:
– Fixed vertical panels perpendicular to the window plane are the most reasonable to ensure shielding of direct light and heat in the morning and afternoon, while ensuring natural ventilation – lighting. Should not be painted too bright, can be a source of glare.
– On the east – west side, it is advisable to use oblique vertical shielding panels for better efficiency.
7.2.3. Ventilated walls: (perforated walls, open walls)
– Use the type of shading structure with many large or small holes combined, decorative, heat-resistant, anti-glare, rain-shielding, well-ventilated, naturally lit and ensuring the requirements of privacy, low cost, meeting aesthetic needs.
– In the case of perforated walls made of brick, ceramic concrete with a large heat absorption coefficient, it should only be used in corridors, stairwells, fence walls, etc.
– In case of using new materials: lightweight metal sheets with heat reflection, they can be used for the vertical face of the house if they meet the aesthetic requirements.
– In the east and west directions, it is advisable to use perforated walls with materials with a small heat accumulation coefficient; ensure receiving direct radiation in winter; can shade in summer, well ventilated and naturally lit. It can be combined with the use of movable glass doors.
– In the north direction, perforated walls should not be used if there are no glass doors to prevent winter cold.
7.2.4. Side corridors are of particular importance in hot and humid tropical architecture, having many functions besides the traffic function:
– The effect of shading, heat prevention, anti-glare, anti-splashing rainwater with a direct radiation shading angle β ≥ 40° to 45° (When the corridor width is from 1.6 m to 1.8 m).
– At latitudes 23°27′ to 15° north, arranging side corridors on the south side is the most reasonable.
– East-west corridors should be combined with other shading systems to increase the rain splash prevention effect of the corridor.
– Corridors should have open railings to increase the efficiency of receiving wind and quickly cooling floor surfaces at night.
7.2.5. Other flexible shading door forms:
a) Shutters: Fixed or movable.
– It is necessary to use shutters made of new materials: avoid being heavy, with a large heat reflection coefficient. Inside, there must also be glass doors to prevent cold winds in winter.
– This type of door has the advantage of shielding rain and sun, anti-glare, ensuring natural ventilation and lighting in all weather conditions.
– In residential houses, movable improved shutters with new materials should be used.
– Aluminum or metal leaf shutters, plastic cord leaves that can be rolled or folded at the top of the window can be used.
b) Folding doors: use the type of metal frame door that can adjust the oblique opening angle according to requirements and can change the shading angle β from 10° to 90°, depending on the sun altitude in each direction.
7.3. Points to note when designing shading structures
7.3.1. Step 1: Determine the shading requirements for the location and orientation of the building.
– Data on natural conditions are taken according to relevant regulations [1]: hours that need shading during the day, month of the year or complete shading, etc.
– In the northern climate conditions (except high mountainous areas), the time to shade the room when the following conditions are met:
+ When the total temperature radiated on the house surface is greater than 27°C;
+ When the intensity of solar radiation into the room I ≥ 230 kcal/m2h;
+ When the indoor air temperature exceeds the allowable limit (when there are conditions, it is necessary to determine the maximum allowable indoor air temperature for each region);
NOTE: In some cases [ti] = 28°C.
+ Shade the dazzling diffusion of the sky within the range of 10° to 20° around the zenith of the northern sky (even without the sun) and refer to the shading condition section;
+ Depending on the functional rooms, natural microclimate or artificial microclimate working comfort conditions, it is necessary to organize additional shading devices: curtains, blinds, shutters;
+ It is necessary to determine the number of sunny hours in the morning, especially in the rainy, winter and spring seasons;
+ Technical conditions and materials also limit the ability to implement shading requirements, so for high-end residential projects, with allowable investment capital, it is necessary to use special structures to implement;
+ The selection of the form and size of the shading structure needs to be combined with the selection of climatic geographical factors and the requirements of shaping art. If, when checked, the shading requirements are not met, other supportive measures must be used;
+ It is necessary to choose the appropriate structure shape and materials – the decisive factor for the shading effectiveness.
7.3.2. Step 2: Determine the reasonable size of the shading structure: the shape and structure of the structure do not allow arbitrary large sizes; therefore, here there must be a balance between active shading and supplementary shading to achieve reasonableness:
– Choose the size of the shading structure to ensure a part or most of the shading requirements;
– Choose the shape of the shading structure, depending on:
+ The shading requirements of the building, expressed on the sun chart at the construction site, the shape is considered reasonable if the shape of the same shading need on the sun chart is similar to the effective shading area of the selected structure (see the section on evaluating shading effectiveness);
+ Figure 7 shows the shading structure shapes with the same effectiveness for selecting shading forms.
When choosing a vertical shading structure, the shading area can be symmetrical or asymmetrical. The angles βt and βp need to be determined correctly corresponding to the left and right of the window (see Figure 8).
a) Angle α is relatively large
b) Angle α is relatively small
c) Vertical shading structure
Figure 7 – Shading structure shapes with the same effectiveness
Figure 8 – Shading area depends on angles βt and βP
+ Determine the size of some shading structure forms:
* In case of horizontal shading structure (see Figure 9).
Bn = Hc.cotgα | Bn = Hc.cos α | Bn = Hc.cosα.sinα Bn = Hc.cos2α |
Figure 9 – Determining the size of the horizontal shading structure
* In case of vertical shading structure (see Figure 10).
Figure 10 – Determining the size of the vertical shading structure
* The angles α, β are determined by the chart of shading and sunlight limit lines combined with the local sun chart.
* Principle of horizontal shading combination by graphics (see Figures 11 and 12).
Figure 11 – Principle of horizontal shading panel combination
Figure 12 – Overhang
7.4. Determining shading and sunlight time
This is a mandatory requirement for residential buildings in order to ensure indoor hygrothermal sanitary indicators – anti-mold, disinfection, etc.
7.4.1. The sunlight problem is the inverse of the shading problem. That is, outside the shading hours are the daytime hours when the room is exposed to sunlight.
7.4.2. To determine the shading and sunlight time, use the sun chart method as in 7.1.
8. Ventilation design
8.1. General requirements for natural ventilation
8.1.1. When designing residential houses, apartments, detached houses, multi-story or low-rise houses, it is necessary to calculate to ensure natural ventilation – cross ventilation – directly or indirectly in the horizontal direction. This is a mandatory condition and right from the planning of the project, the factors affecting the natural ventilation of each house must be considered.
8.1.2. Natural ventilation plays an extremely important role in improving the microclimate conditions and hygiene of living rooms and is one of the four main solutions of hot and humid tropical architecture.
8.1.3. It is necessary to prioritize receiving the prevailing wind in the locality, even if it is hot wind (Southwest) by orienting the façade with the largest surface area towards the main wind direction to create the largest possible aerodynamic pressure difference, the larger the wind pressure difference zone, the better.
8.1.4. It is necessary to create convective airflow by reasonably opening ventilation openings in both winter and summer.
NOTE: Natural ventilation due to wind pressure is usually stronger than due to thermal pressure, in terms of intensity, so it is necessary to prioritize natural ventilation for residential buildings.
8.1.5. When the terrain is complex, it is necessary to consider the influence of wind pressure caused by the terrain.
8.1.6. For high-rise buildings (over 8 floors), due to the higher the altitude, the greater the wind speed exceeding the physiological limit affecting health, especially the elderly and children, so it is necessary to have wind shielding solutions to reduce the wind speed in the room by indirect ventilation (see Figure 13).
8.1.7. For high-rise residential buildings, it is necessary to calculate the natural vertical ventilation solution thanks to the pressure difference between the first floor and the upper floors (see Figure E.12 Appendix E).
8.2. Natural ventilation under the influence of wind
Wind speed depends on the terrain, so the wind speed gradient in height from the ground is not the same.
– Calculating aerodynamic pressure according to the formula:
(1)
Where:
pv: Aerodynamic pressure generated at the calculation point, Pa;
γ0: Specific weight of air at 0°C, kg/m3;
ν: Outdoor wind speed, m/s;
k: Aerodynamic coefficient of the surface at the calculation point (dimensionless);
Figure 13 – Illustration of solutions to reduce direct wind speed into the house (both shading and shielding strong winds directly into the house)
8.1.8. For high-rise residential buildings, it is necessary to calculate the natural vertical ventilation solution thanks to the pressure difference between the first floor and the upper floors (see Figure E.12 Appendix E).
– Aerodynamic coefficient:
(2)
– When calculating, for buildings over 10 m high, it is necessary to consider the wind speed increasing with height, starting from the ground.
– When calculating natural ventilation, it is necessary to consider the pressure on the entire façade: the average wind pressure data should be used.
– Table 2 specifies the ratio of wind speed in different terrains, compared to the wind speed in open areas (at head height).
Table 2 – Ratio of wind speed in different terrains
Terrain | Ratio |
1. Wind flow between houses | 1.3 |
2. Wind flow at the corner of the house | 2.5 |
3. Suction wind flow through the open floor (ground floor, on pillars) | 3.0 |
NOTE: When calculating natural ventilation, it is necessary to take the natural condition data used in construction [1]. |
8.3. Evaluating natural ventilation
To evaluate the effectiveness of natural ventilation, the following three factors should be used:
a) Ventilation flow rate G is the volume of air ventilated in a unit of time (m3/h or m3/s). This indicator aims to ensure the cleanliness of the indoor air when the allowable carbon dioxide concentration according to the hygienic standard for residential buildings is 0.1% (1 ml/l of air).
b) Ventilation multiplier n (number of times the air is replaced with fresh outdoor air) is the ratio between the ventilation flow rate G (m3/hour) and the volume V (m3) of the room:
(times/hour) (3)
c) To evaluate the quality of natural ventilation of residential buildings under the influence of wind, and at the same time select a reasonable architectural solution, it is necessary to consider the ventilation coefficient of the building (Kth):
(4)
(5)
(6)
Where:
vi: Average wind speed;
Vi: Volume of range “i” with moving air;
vlg: Volume of the windless range in the room;
V: Room volume;
𝑉=∑𝑉𝑖+𝑉𝑙𝑔
vn: Calculated wind speed outside the building vn > 0
For civil buildings when the door height hdoor ≥0.4 H (H: room height), K1, K2 can be determined as follows:
(7)
(8)
Where: Fi, Flg and F: the cross-sectional areas corresponding to the volumes Vi, Vlg and V.
If 0 < Kth < 1 then when Kth is close to 1, it is the best ventilation.
8.4. Wind direction and building orientation
8.4.1. The effectiveness of natural ventilation is achieved the highest when the prevailing wind direction makes an angle from 15° to 45° with the normal of the building façade when the buildings are arranged in rows with a reasonable distance between the rows. The effectiveness of natural ventilation depends on the wind direction and the shading structure. Therefore, it is necessary to choose a shading structure that does not affect the ventilation requirements.
Choosing the building orientation needs to be based on the prevailing wind direction in summer at the construction location to balance between ventilation – sun avoidance – aesthetics.
8.4.2. For the climate of high mountainous areas and the North: the best building orientation is the orientation that achieves high ventilation efficiency in summer and avoids winter winds. The cool wind directions are Southeast, South and East.
For the southern climate regions, which are hot almost all year round: the priority of cool wind directions are: Southeast; Southwest; East; West (see Table 3 and Figure 14).
Table 3 – Direction and frequency of prevailing winds (%) in months
(Some localities in the southern climate region)
Month | Wind direction | Ho Chi Minh City | Phan Thiet | Da Lat | Nha Trang | Buon Ma Thuot | Quy Nhon | Pleiku | Da Nang |
I | Main | SE-22 | E-77 | NE-59 | NE-33 | E-87 | N-57 | NE-47 | N-34 |
Sub | E-20 | SE-17 | N-32 | NE-23 | N-22 | NW-22 | |||
V | Main | SE-39 | E-38 | E-27 | NE-33 | E-57 | SE-30 | NW-36 | E-36 |
Sub | S-37 | SE-31 | NE-22 | SE-29 | N-23 | NE-15 | N-32 | ||
II | Main | SW-66 | W-61 | W-33 | SE-58 | W-55 | W-35 | W-69 | N-45 |
Sub | SW-31 | SW-29 | SW-19 | ||||||
X | Main | SW-25 | SE-26 | NE-41 | NE-25 | E-38 | N-46 | W-14 | N-38 |
Sub | SE-15 | E-21 | N-16 | NE-20 | NE-22 | NW-27 |
NORTHERN REGION SOUTHERN REGION CENTRAL COAST
NOTE: In Vietnam, most apartment buildings under 5 floors are designed with a side corridor, so both sides of a room have windows. The main orientation of the building is understood as the orientation of the building with a corridor with windows and doors.
Figure 14 – The best building orientations that can be applied in Vietnam
8.5. Influence of architectural planning on natural ventilation
8.5.1. When designing the architectural planning of a complex of works, it is necessary to evaluate the ventilation effectiveness in the entire neighborhood, residential group because it determines the ventilation for each house.
It is necessary to compare the ventilation solutions in the residential area planning options to choose the most advantageous option.
8.5.2. When planning the architecture of a residential area, neighborhood, it is necessary to note the factors affecting the natural ventilation of the area as follows:
– Building orientation, wind direction in the area;
– Location, size, arrangement of buildings, arrangement of trees (tall trees, low trees, shrubs, large-leaved trees, small-leaved trees, trees with many leaves and few leaves, grass mats, etc.), traffic roads;
– Space combination of the city or residential area under consideration;
8.6. Organizing natural ventilation in residential buildings
8.6.1. The quality of natural ventilation in residential buildings in hot and humid tropical regions is assessed by the velocity and area directly ventilated through the room (cross ventilation), especially living rooms, working rooms, bedrooms, dining rooms, etc.
The quality of natural ventilation depends entirely on the spatial solution (on the horizontal and vertical sections) and the shape, size, position, and structure of the house, after determining the reasonable position and orientation of the house on the overall layout of the entire residential area.
8.6.2. It is not allowed to arrange obstructions and spaces that block the airflow. When there are parts that obstruct the wind, it is necessary to create wind corridors to the using spaces behind (Figure 15).
Figure 15 – Organizing ventilation corridors through many spaces
Figure 16 introduces the influence of the door opening position on the path of the airflow, for the designer to choose a reasonable door arrangement.
Figure 16 – Influence of door opening position on natural ventilation
8.6.3. When specifically designing each residential building, it is necessary to note the following issues (affecting natural ventilation in the house).
– Organization of the building’s layout and space;
– Location, shape, size of window openings;
– Door construction, shading structure and other architectural details: balconies, loggias, overhanging roofs, lobbies, corridors.
8.6.4. Choosing the window size on both sides of the room.
a) The selection of the size ratio of the inlet and outlet windows is very important, not only to increase the air flow rate but also to increase the air flow velocity through the room.
b) The wind flow rate when the wind speed increases at the openings is determined by the formula:
(m³/s) (9)
Where:
μ: Flow coefficient of the opening;
ν: Wind speed through the opening, m/s;
F: Opening area, m2.
c) The inlet should have a larger area than the outlet
d) According to the laws of aerodynamics, the wind speed in the room will increase when the size ratio of the outlet to inlet openings is close to 1.5 times.
e) Position, area, window construction:
+ In the organization of natural ventilation in the “open architecture” style, the larger the window area, the better. The main issue is choosing the direction of opening the inlet and outlet windows.
+ The window width should not be less than 0.5 times the room width. To ensure the width of the zone with high wind speed, the window area should not be less than 60% of the room area.
+ The window construction plays an important role. Due to the requirements of shading and rain shielding, it is necessary to consider the influence of the shading structure on the flow rate and wind direction through the room. Therefore, it is necessary to choose a shading structure that has little effect on the wind flow rate and has the ability to direct the airflow to the necessary areas in the living room (combined with the use of vertical and horizontal baffles to direct the airflow).
The window height must be determined from the requirements of health, minimum air change rate, allowable ventilation rate.
f) Air flow rate for room cooling
Outside air with temperature te (°C) when entering the room is raised to the indoor temperature ti (°C). When leaving the room, the air carries away an amount of heat:
Qg = Cρ0 * G(tI – te) (10)
Where:
Qg: Excess heat that needs to be ventilated, W;
C: Specific heat of air, J/kg°C;
ρ0: Specific mass of air at 0°C, kg/m3;
G: Ventilation flow rate, m3/s.
Typically, the value Cρ0 = 1.2×103 J/°C.m3.
Then we have the necessary air flow rate:
(m3/s) (11)
with ∆t = ti – te (°C)
8.7. Mechanical and semi-mechanical ventilation in residential buildings
8.7.1. Residential buildings in urban areas must be designed with vertical mechanical and semi-mechanical ventilation systems, especially sanitary areas and kitchens.
8.7.2. Stairwells and courtyards (buildings over 5 floors) can be combined as the main ventilation ducts. There must be a system of air vents on the roof to adjust the airflow velocity according to weather changes.
8.7.3. When necessary, it is possible to combine the arrangement of a ventilation fan system or ventilation turbines due to the pressure difference between the first floor and the upper floors.
9. The role of green trees and water surfaces in architectural planning, shading, heat/cold prevention for residential buildings
9.1. Air purifying effect of green trees
– Provide the main oxygen for the living environment.
– Have the ability to filter and retain dust (especially suspended dust in the air).
FOR EXAMPLE: Maple leaves can retain from 21% to 80% of the dust amount within the area the tree occupies.
– Some plant species also release phytoncides into the environment, which have the ability to inhibit and kill pathogenic bacteria;
– Have the effect of ionizing the air (balancing negative and positive ions), which is beneficial for human health.
– Have the ability to absorb harmful gases in the air.
– Have the ability to remove toxins from wastewater where sewers discharge into rivers, even wastewater with low radioactive content.
FOR EXAMPLE: Water hyacinth filters clean water, reed roots have the ability to absorb harmful chemicals in industrial wastewater. (See Appendix K)
9.2. Effect of reducing solar radiation by green trees
– Absorb solar energy for photosynthesis: absorb from 30% to 80% of direct solar radiation. Depending on whether the tree has many or few leaves, a wide or narrow canopy, large or small leaves.
– Block solar radiation, create shade for the space under the canopy and architectural surfaces: walls, roofs, roads and ground surfaces, etc.
+ Can block from 40% to 90% of the amount of solar radiation;
+ Thick grass mats block 80% of the radiation shining on the ground.
– Minimize reflected radiation to the surrounding environment due to a lower thermal reflectance compared to other surfaces.
NOTE: The ratio of reflected radiation from the surface to the total solar radiation shining on that surface is called the albedo coefficient A. This coefficient depends on the surface characteristics, physical properties, color and state of that surface). The albedo coefficient (A) has the effect of reducing the reflected radiation of climbing plants on walls. The larger the leaves, the larger and denser the canopy, the greater the radiation blocking ability.
9.3. Comprehensive effects of green trees and water surfaces on improving microclimate conditions, temperature, air humidity
– Increase air humidity in areas shaded by green trees because the shaded areas have lower air temperatures: increase from 5% to 8% compared to areas without green trees.
– Reduce air temperature in the area under the tree canopy in summer, lower than the air temperature in open areas in summer from 0.8°C to 3°C.
– Air temperature in areas with many green trees and water surfaces is usually lower than air temperature in areas without green trees and water surfaces in summer from 2°C to 3°C.
9.4. Influence of green trees and water surfaces on wind regime and air movement flow
– If trees are arranged appropriately, they will have the effect of blocking too strong winds in summer and blocking cold winds in winter.
– Green trees can direct the air movement flow in a direction that is beneficial for cross-ventilation of the house.
– When planting trees on both sides of the street, it will create a corridor, cool ventilation for the city, and at the same time can partially block hot winds in hot and dry climates (Central region).
9.5. Aesthetic effects of green trees – water surfaces
The combination of trees – water surfaces in any large or small scope indoors and outdoors creates effects that reduce human stress.
9.6. Principles of tree arrangement
a) Classify green trees according to the nature of use:
– Green trees for public use in urban areas (planted in residential areas or public areas or parks);
– Green trees for limited use (indoors and outdoors, apartments);
– Green trees for special purposes (used according to purpose).
b) Specifically for residential buildings, there are two main types:
– Exterior green trees: usually large climbing and small woody trees with a height of 0.5 m to 3 m.
– Interior green trees: usually low, small from 0.1 m to 1.5 m combined with the art of bonsai – miniature landscapes.
(Refer to Appendix K on the toxic gas removal properties of green trees)
10. Designing thermal insulation against heat for building envelopes
10.1. General requirements for thermal insulation in hot seasons
10.1.1. For buildings using natural microclimate:
– Walls and roofs located in the direction with the largest solar radiation in summer must be designed with thermal insulation;
– Combine with natural ventilation is an important factor to improve the indoor microclimate of residential buildings;
– Combine with shading solutions such as green trees, shading structures, etc. to create a good microclimate for living rooms;
– Avoid increasing the inner surface temperature of the building envelope (causing a feeling of heat due to radiation from the inner surface of the building envelope);
– When designing thermal insulation, refer to TCVN 4605:1988 and relevant regulations.
10.1.2. For residential buildings using artificial microclimate:
– Must calculate thermal insulation for building envelopes to reduce energy consumption;
– When designing thermal insulation, refer to TCVN 4605:1988, TCXD 232:1999 and relevant regulations.
10.1.3. Main roof types and thermal insulation solutions:
a) Sloped roofs:
Usually use an attic with ventilation openings to exchange heat with the outside air (houses with ceilings);
If there is no ceiling, it is necessary to make a row of ventilation openings at the base of the roof or gable walls.
b) Flat roofs with thermal insulation:
Design an additional air circulation layer in the roof (double roof) or on the roof (single roof), but all must have technical solutions to ensure good, durable waterproofing.
c) Roofs with water spraying, water storage, water flowing in circulation:
It is necessary to have solutions and materials for absolute waterproofing
10.1.4. Insulated walls (refer to Figure D. 4 Appendix D)
– Walls facing East and West receive the maximum solar radiation and must have thermal insulation solutions.
– Insulated walls need to ensure thermal insulation during the day and rapid heat dissipation at night. The lighter the wall weight, the better (often using foam concrete, slag concrete, gravel concrete, ceramic or walls with hollow thermal insulation structures). The outer surface is painted with a color with a high reflectance.
10.2. Measures to prevent condensation on the floor surface
10.2.1. There are two processes of water condensation on the floor surface and equipment: condensing into a water film and condensing into water droplets.
10.2.2. The conditions for the formation of water condensation on the floor surface and equipment often occur when the air temperature and humidity suddenly increase while the surface temperature of the floor, walls, and equipment have not yet increased and are smaller than the dew point temperature of the air (ts) tbm ≤ ts.
10.2.3. Principles of preventing water condensation on the floor surface and equipment:
a) Reduce indoor air humidity;
b) Raise the surface temperature of the structure higher than the dew point temperature.
NOTE: One of the three solutions or a combination of all three solutions can be used.
10.2.4. Principles of designing floors to prevent water condensation (anti-condensation).
a) Calculation and design method according to TCXD 230:1998.
b) Some design indicators of anti-condensation floors:
– Choose a floor structure with a surface layer with the smallest thermal inertia (D), thermal stability coefficient (Y) and equivalent thermal conductivity to make the surface temperature change quickly according to the ambient temperature. If the floor surface temperature (tbm) is greater than the dew point temperature of the air (ts), as in 10.2.2, then the anti-condensation ability of the floor is determined according to the following empirical expression:
∆t = f (Y)(see Figure 17 and Figure 18) |
Figure 17 – Graph for evaluating anti-condensation effectiveness ∆T = 0.7351N Y-1.383
Figure 18 – Heat transfer from the floor surface structure to the ground layer of the floor
+ The best anti-condensation floor indicators are:
∆t ≤ 0.05; Y ≤ 6.5; λtd ≤ 0.35 (12)
+ The condensation limiting indicators of the floor are:
∆t ≤ 0.00; 6.6 ≤ Y ≤ 8.3 (13)
0.36 ≤ λtd ≤ 0.60
Where:
∆t: Temperature difference between the dew point temperature of the air and the floor surface temperature, °C;
(14)
Y: Thermal stability coefficient of the floor structure surface; Y depends on the “thick” or “thin” surface layer of the floor structure (i.e. the thermal inertia index D is greater than or less than 1);
λtd: Equivalent thermal conductivity of the floor structure, depending on the physical properties of the floor layer materials and the thickness of those layers.
(15)
δi: Thickness of the i-th floor layer, m;
λi: Thermal conductivity of the i-th floor layer of the floor structure, W/(m.K).
– The floor has anti-condensation ability when ∆t < 0; or ranging from 0°C to 1°C; or Y = 6.6 ÷ 1.6 (W/(m.K).
– Designing anti-condensation floors is the selection of materials and structures with Y; λtd = min, within the above limits while still ensuring the economy and load-bearing capacity of the floor.
The smaller these values, the higher the anti-condensation ability.
– Suitable materials for anti-condensation floors are thin finishing materials such as: ceramic tiles, wood or composite plastic panels, lightweight insulating materials such as polystyrene, polyurethane, foam ceramics.
10.2.5. Method of calculating the surface thermal stability coefficient of a multi-layer floor structure:
– The thermal inertia index D of a multi-layer floor structure is determined by the formula:
(W/(m.K) (16)
Where:
: Thermal resistance of the i-th floor structure,
δi : thickness of the i-th floor layer, m;
: Heat absorption coefficient of the i-th layer material.
– The surface thermal stability coefficient is calculated as follows:
If the i-th layer structure of the floor has Di ≥ 1, we have:
Yi = Si
If Di < 1 and at the same time Di + Di + 1 ≥ 1, i.e. the surface thermal stability coefficient considering the influence of the (i + 1)-th layer is as follows:
(17)
If Di + Di + 1 < 1 then:
(18)
– When condensation occurs, heat is transmitted from the floor surface downward through layers i, i + 1…, m) numbered as in Figure 24.
– When designing anti-condensation floors, materials should be selected so that only 2 to 3 layers of materials are sufficient to ensure ΣDi ≥ 1.
– For floors with a closed air layer in the floor structure, the heat absorption coefficient of the air layer is considered zero (Sk = 0).
– With a closed air layer with a thickness:
δ = from 15 mm to 20 mm, take λk = 0.05;
δ = from 21 mm to 25 mm; take λk = 0.09.
10.2.6. Appropriate anti-condensation floor structure solutions:
It is necessary to choose an appropriate floor structure solution so that the floor surface isolates the influence of temperature, humidity, and thermal inertia of the ground. It is necessary to use materials with low thermal inertia and high thermal conductivity to limit water condensation on the floor surface. The structure of the layers should be selected as follows: (see Figures 19 to 25).
– Layer 1: High mechanical layer – is a layer with aesthetic requirements, high wear resistance, high mechanical durability, large thermal inertia – materials with the smallest possible thickness should be used; Suitable finishing materials are: fired ceramic tiles with a thickness of ≤ 10 mm; ceramic tiles δ ≤ 7 mm; composite plastic panels δ ≤ 5 mm; packet wood or flooring δ ≤ 15 mm.
– Layer 2: Bonding mortar layer with δ ≤ from 10 mm to 20 mm; this layer should be as thin as possible. Currently, if conditions permit, adhesive should be used to remove the bonding mortar layer;
– Layer 3: Basic thermal insulation layer, with low thermal inertia; it is necessary to choose materials that can both withstand loads and have high thermal resistance;
– Layer 4: Waterproofing layer to protect the insulation layer from moisture caused by capillary action from the ground; Can use: bitumen paper, polyethylene membrane, rubber bitumen paint with coarse fabric or gauze reinforcement;
– Layer 5: Load-bearing concrete layer (or rubble concrete);
– Layer 6: Compacted ground (or black sand).
LEGEND: 1- Floor surface material layer 2- Water-resistant layer 3- Thermal insulation material layer 4- Waterproofing layer 5- Load-bearing concrete layer or rubble concrete 6- Ground |
Figure 19 – Structure of anti-moisture floor layers
LEGEND: 1- Ceramic tiles 7 mm thick, joints filled with cement 2- Grade 25 mortar, 20 mm thick 3- Blast furnace slag granules 200 mm thick with γ0 from 700 kg/m3 to 900 kg/m3 and λ0 from 0.15 kcal/m.h.°C to 0.19 kcal/m.h.°C 4- Waterproofing membrane made of oil paper, rubber bitumen paint (or yellow sand cement mortar 20 mm thick) 5- Rubble concrete grade ≥ 75, 100 mm thick (or gravel concrete 70 mm thick); Y = 4.8 kcal/m2.h.°C |
Figure 20 – Anti-condensation floor sample using granular blast furnace slag
1- Granite steel mesh concrete floor tiles, size 400 mm x 400 mm x 20 mm 2- Air layer 20 mm thick 3- Yellow sand cement mortar grade 100, 20 mm thick 4- Rubble concrete grade ≥ 75, 100 mm thick Y = 5.2 kcal/m2.h.°C |
Figure 21 – Anti-condensation floor sample using granitô tiles with closed air layer
1- Floor surface made of ironwood (or plywood, packet) 20 mm thick 2- Air layer 20 mm thick 3- Yellow sand cement mortar grade 100, 20 mm thick 4- Rubble concrete grade ≥ 75, 100 mm thick (or gravel concrete 70 mm thick) Y = 4.2 kcal/m2.h.°C |
Figure 22 – Anti-condensation floor sample using wood flooring with closed air layer
1- Ceramic tiles 7 mm thick, joints filled with cement 2- Adhesive layer or bitumen paint (not diluted with gasoline) 3- High-strength polystyrene 25 mm thick with Rn ≥ 20 daN/cm2; γ0 from 30 kg/m3 to 60 kg/m3 4- Waterproofing layer made of oil paper, rubber bitumen paint or yellow sand cement mortar 20 mm thick 5- Rubble concrete grade ≥ 75, 100 mm thick (or gravel concrete 70 mm thick) Y from 2.19 kcal/m2.h.°C to 2.64 kcal/m2.h.°C |
Figure 23 – Anti-condensation floor sample using high-strength polystyrene foam material
1- Ceramic tiles 7 mm thick, joints filled with cement 2- Foam ceramic with γ0 = 540 kg/m3; Rn ≥ 45 daN/cm2, 60 mm thick, bonded to the ceramic tile layer with cement mortar (or rubber bitumen paint layer) 3- Waterproofing layer made of yellow sand cement mortar grade 100, 20 mm thick (or rubber bitumen paint layer or oil paper) 4- Rubble concrete grade ≥ 75, 100 mm thick Y = 2.46 kcal/m2.h.°C |
Figure 24 – Anti-condensation floor sample using foam ceramic
1- Ceramic tiles 7 mm thick, joints filled with cement 2- High-strength polystyrene foam material 15 mm thick (Rn ≥ 20 daN/cm2; γ0 from 30 kg/m3 to 60 kg/m3) bonded to ceramic tiles with glue (or rubber bitumen paint layer not diluted with gasoline) 3- Yellow sand cement mortar grade 100, 20 mm thick (or 10 mm thick with an additional layer of rubber bitumen paint) 4- Rubble concrete grade ≥ 75, 100 mm thick Y = 2.56 kcal/m2.h.°C |
Figure 25 – Anti-condensation floor sample using a combined insulation layer of foam ceramic concrete and high-strength polystyrene
Appendix A (Reference) Air state chart (I-d chart)
Figure A.1- I-d chart of moist air when the atmospheric pressure is 760 mmHg)
Appendix B (Reference) Physical quantities used in the calculation of thermal insulation design for residential buildings
Table B.1- Symbols of physical quantities
Name | Symbol | Unit | |
Technical system | SI system | ||
1. Calculated indoor air temperature | Ti | 0C | (0C + 273) 0K |
2. Inner surface temperature of the building envelope | θt (ti) | 0C | (0C + 273) 0K |
3. Highest indoor surface temperature | θtmax (timax) | 0C | (0C + 273) 0K |
4. Dew point temperature | ts | 0C | (0C + 273) 0K |
5. Amplitude of calculated outdoor temperature fluctuation | Ate | 0C | (0C + 273) 0K |
6. Amplitude of calculated indoor temperature fluctuation | Ati | ||
7. Amplitude of inner surface temperature fluctuatio | Aqi | 0C | (0C + 273) 0K |
8. Solar radiation absorption coefficient | ε | ||
9. Heat absorption coefficient of material layers | B | ||
10. Total attenuation coefficient of temperature fluctuation of the building envelope | νo | ||
11. Attenuation coefficient of temperature fluctuation from indoor air to inner surface | ν | ||
12. Calculated wind speed | v | m/s | m/s |
13. Average wind speed | vtb | ||
14. Thickness of the building envelope layer | δ | m | m |
15. Heat transfer surface area of the building envelope | F | m2 | m2 |
16. Material mass | M | kg/m3 | kg/m3 |
17. Specific heat capacity | c | kcal/Kg.0C | kJ/kg.0K |
18. Number of heating days, hours | Z(d) | giờ | h |
19. Number of cooling days, hours | Sm | giờ | h |
20. Outdoor surface heat transfer coefficient | αe | kcal/m2.h.0C | W/m2.0C |
21. Indoor surface heat transfer coefficient | αi | kcal/m2.h.0C | W/m2.0C |
Appendix C (Reference) Map of construction climatic zones in Vietnam
NOTES:
1. Northern climate region: Includes provinces north of the Hai Van Pass
– Characteristics: basically a tropical monsoon climate with a cold winter.
– A.l. Northeast and Viet Bac climate zone
+ Characteristics: Lowest temperature below 0°C, wet and humid climate, heavy rain, cold prevention is the main focus.
A.I.1. Subzone including Northeast provinces
Differ in the level of heating
A.I.2. Subzone including Viet Bac provinces
– A.ll. Northwest and Northern Truong Son mountainous climate zone
+ Characteristics: less cold, lowest temperature ≥ 0°C in the North and ≥ 5°C in the South, hot and dry weather with highest temperature of 40°C, cold wind speed ≥ 40m/s, the cold season lasts as long as the dry season, heating demand from two to three months.
A.ll.1. Northwest subzone
Differ in the level of winter heating
A.II.2. Northern Truong Son subzone
– A.lll. Red River Delta and North Central climate zone
+ Characteristics: Cold winter, down to 0°C in the north and 5°C in the south; hottest is 40°C from Thanh Hoa southward, can reach 42°C – 43°C, more humid climate than A.l and A.ll, heavy rain, wind speed greater than 40m/s.
A.III.1. Red River Delta subzone
A.III.2. Thanh Hoa, Nghe An, Ha Tinh plains subzone
Differ in winter heating technical solutions
A.III.3. Quang Binh, Quang Tri, Thua Thien Hue plains subzone
2. Southern climate region: includes provinces south of the Hai Van Pass
– Characteristics: monsoon temperature all year round with only one hot season.
– B.IV. Central Highlands climate region
+ Characteristics: Tropical climate characteristics, lowest temperature from 0°C to 5°C, highest ≥ 40°C, from the mountainous area, it is necessary to prevent and combat heat for this region.
B.IV.1. Northern Central Highlands subzone
Differ in the demand for cold prevention
B.IV.2. Southern Central Highlands subzone
– B.V. Southern and Central plains climate zone
+ Characteristics: tropical climate, not cold in winter, lowest temperature ≥ 10°C, highest ≤ 40°C in the North; ≥ 40°C in the South; heavy rainfall with two dry seasons per year, humidity suitable for two wind seasons.
B.V.1. Quang Nam, Da Nang, Northern Quang Ngai subzone
B.V.2. Khanh Hoa, Southern Quang Ngai subzone
Differ in the demand for heat prevention in summer
B.V.3. Thuan Hai, Southeastern subzone
B.V.4. Southwestern subzone
Appendix D (Reference) Some shading solutions
Figure D.1 – Position of shading panels on the wall surface and shading diagrams corresponding to the type of shading panels
a) Partition wall type | b) Vertical and horizontal shielding panels |
Figure D.2 – Simple types of shading panels
Figure D.3 – Types of ventilated walls for shading and ventilation to reduce the temperature of heat-absorbing objects due to large contact area
Appendix E (Reference) Illustration of guidelines for selecting solutions for planning residential areas – green trees – natural ventilation
(In order to create an outdoor ecological environment – indoor microclimate)
a) Fence adjacent to the house wall, or 3 m away from the house, or 6 m away from the house.
b) Tall trees in the middle of houses by 1.5 m or in the middle of houses by 3 m or in the middle of houses by 15 m.
Figure E.1 – Distance of fences, green trees and the effectiveness of cross-ventilation
Figure E.2 – How to arrange houses on slopes
Figure E.3 (A) – Relationship between tall trees and bushes (fences) and ventilation for houses a, b, c
Figure E.3 (B) – How to solve ventilation when direct wind cannot be received
NOTE: Arranging green strips – grass mats, tall trees, bushes, water surfaces appropriately can reduce the outdoor temperature by 1.5°C to 2.5°C and reduce the solar radiation intensity by 40% to 50%; reduce strong wind speed by 50% to 60%; reduce the dust content of the air by 25% to 40%; increase the relative humidity of the outdoor air by 7% to 12% compared to the location without green trees.
Figure E.4 – Arranging doors to have wind passing through the rooms | Figure E.5 – House shape and wind pressure zones |
Figure E.6 – Arranging doors to receive cross-ventilation wind
Figure E.7 – How to arrange houses to receive prevailing winds
Figure E.8 – How to ventilate through roof gaps
Figure E.9 – Types of house arrangements and ventilation effectiveness | Figure E.10 – It is necessary to arrange low-rise houses in front and high-rise houses behind in relation to the wind direction |
Figure E.11 – How to open doors to benefit cross-ventilation
High reflectance coefficient of the roof surface
Figure E.12 – Horizontal ventilation for apartments thanks to the vertical air movement flow along stairwells or courtyards | Figure E.13 – Arranging doors in height to create natural ventilation effectiveness |
Appendix F (Reference) Thermal resistance of common roof and ceiling structures
Table F.1 – Thermal resistance of flat roofs when the heat flow direction is upward
Type | Structure | Material layers | Thermal resistance m2.K/W | |
Symbol | Material | |||
Assembled from concrete slabs, gypsum boards | 1 | Outer surface | 0.03 | |
2 | Bitumen fabric roofing 10 mm | 0.06 | ||
3 | Concrete structure 100 mm | 0.07 | ||
4 | Air layer 100 mm | 0.17 | ||
5 | Gypsum boar 13 mm | 0.08 | ||
6 | Inner surface | 0.11 | ||
R0 | Total thermal resistance | 0.52 | ||
Assembled roofing system | 1 | Outer surface | 0.03 | |
2 | Light gravel (ceramic gravel) 100 mm | 0.10 | ||
3 | Waterproofing layer | 0.05 | ||
4 | Porous insulation layer | 3.00 | ||
5 | Load-bearing concrete 100 mm | 0.07 | ||
6 | Gypsum board lining 13 mm | 0.08 | ||
7 | Inner surface | 0.11 | ||
R0 | Total thermal resistance | 3.45 | ||
Wood and gypsum board assembled | 1 | Outer surface | 0.03 | |
2 | Bitumen membrane | 0,06 | ||
3 | Hardwood 19 mm | 0.10 | ||
4 | Air layer 100 mm | 0.17 | ||
5 | Gypsum board 13 mm | 0.08 | ||
6 | Air layer | 0.11 | ||
R0 | Total thermal resistance | 0.55 | ||
Thin metal sheet Fibrous insulation layer (compressed straw board) painted surface | 1 | Outer surface | 0.03 | |
2 | Metal roofing layer (corrugated iron) | 0 | ||
3 | Fibrous insulation layer | 0.15 | ||
4 | Compressed straw layer | 0.62 | ||
5 | Air layer | 0.11 | ||
R0 | Total thermal resistance | 2.26 | ||
Metal roofing sheet Thin metal reflective sheet Gypsum boar | 1 | Outer surface | 0.03 | |
2 | Metal roofing sheet | 0 | ||
3 | Air layer 25 mm | 0.30 | ||
4 | Metal reflective sheet | 0 | ||
5 | Air layer 100 mm | 0.48 | ||
6 | Gypsum board 13 mm | 0.08 | ||
7 | Outer surface | 0.11 | ||
R0 | Total thermal resistance | 1.00 | ||
Metal roofing sheet Porous insulation layer Metal reflective sheet Gypsum board | 1 | Outer surface | 0.03 | |
2 | Metal roofing sheet | 0 | ||
3 | Fibrous insulation layer | 1.50 | ||
4 | Metal reflective sheet | 0 | ||
5 | Air layer 100 mm | 0.36 | ||
6 | Gypsum board 13 mm | 0.08 | ||
7 | Outer surface | 0.11 | ||
R0 | Total thermal resistance | 2.20 | ||
Metal roofing sheet Porous insulation layer Metal reflective sheet Gypsum board | 1 | Outer surface | 0.03 | |
2 | Metal roofing sheet | 0 | ||
3 | Fibrous insulation layer | 1.50 | ||
4 | Metal reflective sheet | 0 | ||
5 | Air layer 50 mm | 0.42 | ||
6 | Glass sheet | 1.30 | ||
7 | Gypsum board | 0.08 | ||
8 | Outer surface | 0.11 | ||
R0 | Total thermal resistance | 3.44 | ||
Insulated roof with assembled membrane | 1 | Outer surface | 0.03 | |
2 | Light gravel (light gravel) 60 mm | 0.04 | ||
3 | Prefabricated steel mesh | 0 | ||
4 | Fibrous insulation layer | 2.00 | ||
5 | Waterproofing membrane (oil paper, rubber bitumen) | 0.01 | ||
6 | Reinforced concrete layer 100 mm or wood board 25 mm | 0.19 | ||
7 | Gypsum board | 0.08 | ||
8 | Outer surface | 0.11 | ||
R0 | Total thermal resistance | 2.33 | ||
Reinforced concrete | 2.46 | |||
Wood board |
Table F.2 – Thermal resistance of flat roofs when the heat flow direction is downward
Type | Structure | Material layers | Thermal resistance m2.K/W | |
Symbol | Material | |||
Assembled concrete slabs Gypsum boardTấm thạch cao | 1 | Outer surface | 0.03 | |
2 | Bitumen roofing membrane 10 mm | 0.06 | ||
3 | Hardwood flooring 19 mm | 0.07 | ||
4 | Air layer 100 mm | 0.17 | ||
5 | Gypsum board 13 mm | 0.08 | ||
6 | Inner surface | 0.11 | ||
R0 | Total thermal resistance | 0.52 | ||
Assembled roofing system | 1 | Outer surface | 0.03 | |
2 | Light gravel 100 mm | 0.10 | ||
3 | Waterproofing membrane | 0.06 | ||
4 | Porous insulation layer | 3.00 | ||
5 | Reinforced concrete 100 mm | 0.07 | ||
6 | Gypsum board 13 mm | 0.08 | ||
7 | Inner surface | 0.11 | ||
R0 | Total thermal resistance | 3.45 | ||
Assembled wood, gypsum board | 1 | Outer surface | 0.03 | |
2 | Bitumen roofing membrane | 0.06 | ||
3 | Hardwood flooring 19 mm | 0.10 | ||
4 | Air layer 100 mm | 0.17 | ||
5 | Gypsum board | 0.08 | ||
6 | Inner surface | 0.11 | ||
R0 | Total thermal resistance | 0.55 | ||
Metal roofing sheet Porous insulation layer Compressed straw board | 1 | Outer surface | 0.03 | |
2 | Metal roofing sheet | 0 | ||
3 | Porous insulation layer | 0.15 | ||
4 | Compressed straw | 0.62 | ||
5 | Inner surface | 0.11 | ||
R0 | Total thermal resistance | 2.26 | ||
Metal roofing sheet Thin reflective metal sheet Gypsum board | 1 | Outer surface | 0.03 | |
2 | Metal roofing sheet | 0 | ||
3 | Air layer 25 mm | 0,30 | ||
4 | Reflective metal sheet | 0 | ||
5 | Reflective air layer 100 mm | 1.42 | ||
6 | Gypsum board 13 mm | 0.08 | ||
7 | Outer surface | 0,11 | ||
R0 | Total thermal resistance | 1.94 | ||
Metal roofing sheet Porous insulation layer Reflective metal sheet Gypsum board | 1 | Outer surface | 0.03 | |
2 | Metal roofing sheet | 0 | ||
3 | Porous insulation layer | 1.50 | ||
4 | Ventilated air layer 100 mm | 0 | ||
5 | Gypsum board | 1.42 | ||
6 | Gypsum board 13 mm | 0.08 | ||
7 | Outer surface | 0.11 | ||
R0 | Total thermal resistance | 3.14 | ||
Metal roofing sheet Porous insulation layer Reflective metal sheet Gypsum board | 1 | Outer surface | 0.03 | |
2 | Metal roofing sheet | 0 | ||
3 | Porous insulation layer | 1.50 | ||
4 | Reflective metal sheet | 0 | ||
5 | Ventilated air layer | 1.00 | ||
6 | Glass wool | 1.30 | ||
7 | Gypsum board | 0.08 | ||
8 | Inner surface | 0.11 | ||
R0 | Total thermal resistance | 4.44 | ||
Insulated roof with assembled membranes | 1 | Outer surface | 0.03 | |
2 | Light gravel 60 mm | 0.04 | ||
3 | Prefabricated steel mesh | 0 | ||
4 | Porous insulation layer | 2.00 | ||
5 | Waterproofing membrane (fabric layer or bitumen) | 0.01 | ||
6 | Reinforced concrete 100 mm or wood board 25 mm | 0.19 | ||
7 | Gypsum board 13 mm | 0.08 | ||
8 | Inner surface | 0.11 | ||
R0 | Total thermal resistance | |||
Reinforced concrete | 2.33 | |||
Wood board | 2.46 |
Table F.3 – Thermal resistance of sloped roofs when the heat flow direction is downward
Type | Structure | Material layers | Thermal resistance m2.K/W | |
Symbol | Material | |||
Tile roof, gypsum board ceiling | 1 | Outdoor air layer | 0.03 | |
2 | Fired clay tile 19 mm | 0.02 | ||
3 | Attic space (air layer) | 0.46 | ||
4 | Gypsum board 13 mm | 0.08 | ||
5 | Indoor air layer | 0.11 | ||
R0 | Total thermal resistance | 0.70 | ||
Tile roof, insulation layer, gypsum board lining | 1 | Outdoor air layer | 0.03 | |
2 | Fired clay tile 19 mm | 0.02 | ||
3 | Attic space (air layer) | 0.46 | ||
4 | Porous insulation layer | 2.00 | ||
5 | Gypsum board 13 mm | 0.08 | ||
6 | Indoor air layer | 0.11 | ||
R0 | Total thermal resistance | 2.70 | ||
Tile roof, heat-reflecting metal sheet, gypsum board | 1 | Outdoor air layer | 0.03 | |
2 | Fired clay tile 19 mm | 0.02 | ||
3 | Air layer 25 mm | 0.15 | ||
4 | Reflective metal sheet | 0 | ||
5 | Ventilated air layer | 1.36 | ||
6 | Gypsum board 13 mm | 0.08 | ||
7 | Indoor air layer | 0.11 | ||
R0 | Total thermal resistance | 1.75 | ||
Galvanized steel, foam insulation board | 1 | Outdoor air layer | 0.03 | |
2 | Metal roofing sheet | 0 | ||
3 | Attic space | 0.28 | ||
4 | Foam board 12.7 mm | 0.25 | ||
5 | Indoor air layer | 0.11 | ||
R0 | Total thermal resistance | 0.67 |
Table F.4 – Thermal resistance of common walls
Type | Structure | Material layers | Thermal resistance m2.K/W | |
Symbol | Material | |||
Cast-in-place concrete, interior wall lining | 1 | Outdoor air layer | 0.04 | |
2 | Concrete (2 400 Kg/m3) 100 mm | 0.07 | ||
3 | Cement-sand plaster (1:4) 20 mm | 0.04 | ||
4 | Indoor air layer | 0.12 | ||
R | Total thermal resistance | 0.32 | ||
Lightweight concrete, ceramic tile facing | 1 | Outdoor air layer | 0.04 | |
2 | Ceramic tile 12.5 mm | 0.01 | ||
3 | Lightweight concrete (porosity 1 900 kg/m2) 100 mm | 0.15 | ||
4 | Indoor air layer | 0.12 | ||
R | Total thermal resistance | 0.32 | ||
Perforated brick, wall pane | 1 | Outdoor air layer | 0.04 | |
2 | Solid brick masonry 110 mm | 0.10 | ||
3 | Ventilated air layer 50 mm | 0.14 | ||
4 | Solid brick masonry 110 mm | 0.10 | ||
5 | Plaster, cement-sand 20 mm | 0.04 | ||
6 | Indoor air layer | 0.12 | ||
R | Total thermal resistance | 0.54 | ||
Concrete block, interior wall lining | 1 | Outdoor air layer | 0.04 | |
2 | Concrete block 190 mm | 0.19 | ||
3 | Plaster, cement-sand (1:4) | 0.04 | ||
4 | Indoor air layer | 0.12 | ||
R | Total thermal resistance | 0.39 | ||
Hollow concrete slab, interior wall lining | 1 | Outdoor air layer | 0.04 | |
2 | Concrete block 90 mm | 0.14 | ||
3 | Ventilated air layer 50 mm | 0.14 | ||
4 | Concrete block 90 mm | 0.14 | ||
5 | Smooth panel, cement-sand (1:4) | 0.04 | ||
6 | Indoor air layer | 0.12 | ||
R | Total thermal resistance | 0.62 | ||
Single wythe masonry, exposed Unplastered masonry (exposed ceiling) | 1 | Outdoor air layer | 0.04 | |
2 | Block masonry 300 mm | 0.04 | ||
3 | Ventilated air layer 50 mm | 0.24 | ||
R | Total thermal resistance | 0.40 | ||
Glazed brick, gypsum board wall lining | 1 | Outdoor air layer | 0.04 | |
2 | Brick masonry 110 mm | 0.10 | ||
3 | Ventilated air layer 150 mm | 0.14 | ||
4 | Gypsum board 10 mm | 0.06 | ||
5 | Indoor air layer | 0.12 | ||
R | Total thermal resistance | 0.46 | ||
Glazed brick, RF1 on outer surface of frame, gypsum board wall lining | 1 | Outdoor air layer | 0.04 | |
2 | Brick masonry 110 mm | 0.10 | ||
3 | Convection (ventilated) air layer 50 mm | 0.55 | ||
4 | Reflective metal sheet | 0 | ||
5 | Reflective air layer 100 mm | 0.61 | ||
6 | Gypsum board 10 mm | 0.06 | ||
7 | Indoor air layer | 0.12 | ||
R | Total thermal resistance | 1.48 | ||
Rain and sun shading panel (pine), gypsum board, gypsum board wall lining | 1 | Outdoor air layer | 0.04 | |
2 | Rain and sun shading panel (pine) 12 mm | 0.05 | ||
3 | Air layer (closed) | 0.16 | ||
4 | Gypsum board | 0.06 | ||
5 | Indoor air layer | 0.12 | ||
R | Total thermal resistance | 0.47 | ||
Fiber cement board, polyester plastic sheet | 1 | Outdoor air layer | 0.04 | |
2 | Fiber cement board | 0.02 | ||
3 | Polyester plastic sheet 25 mm | 0.67 | ||
4 | Fiber cement board | 0.02 | ||
5 | Indoor air layer | 0.12 | ||
R | Total thermal resistance | 0.87 |
Table F.5 – Thermal resistance of common building material structures
Material | Thickness | Specific mass kg/m3 | Thermal resistance m2.K/W |
1. Fiber cement board | 300 | 1 500 | 0.24 |
2. Fiber cement, deep corrugated | 4.5 | 1 200 | 0.02 |
6.0 | 1 200 | 0.03 | |
6.4 | 1 400 | 0.02 | |
3. Brick masonry (membrane fired clay brick wall) | 110 | 1 600 | 0.10 |
4. Compressed pine wood wall | 12 | 256 | 0.23 |
5. Concrete block | 190 | 980 | 0.19 |
90 | 1 300 | 0.14 | |
6. Concrete, structure | 100 | 2 400 | 0.07 |
7. Hardwood board | 4.8 | 940 | 0.03 |
5.5 | 940 | 0.03 | |
6.0 | 103 | 0.13 | |
8. Metal roofing sheet – aluminum – protective coated steel sheet | Not considering the thermal resistance itself, also contributes to the thermal resistance of adjacent air layers or air layers depending on the diffusivity of the surface, direction and orientation of the heat flow (see Tables E.3, E.4, E.5) | ||
9. Board made of loose particles | 6 | 660 | 0.05 |
8 | 660 | 0.07 | |
10 | 620 | 0.08 | |
10. Sand-lime cement | 13 | 1 570 | 0.02 |
19 | 1 570 | 0.02 | |
9 | 1 100 | 0.03 | |
Gypsum | |||
11. Sand-lime aggregate | 13 | 1 680 | 0.02 |
19 | 1 680 | 0.02 | |
12. Lightweight aggregate (ceramic gravel) | 13 | 720 | 0.09 |
19 | 720 | 0.13 | |
13. Gypsum board, plastic | 10 | 880 | 0.06 |
13 | 880 | 0.08 | |
16 | 880 | 0.09 | |
14. Plywood – interior | 4 | – | 0.04 |
6 | – | 0.06 | |
10 | – | 0.09 | |
15. Structure grade F8 | 7 | – | 0.06 |
16. Structure grade F11 | 9 | – | 0.08 |
6 | – | 0.03 | |
7 | – | 0.04 | |
Soft board | 0 | ||
17. Polished wood board | 12.7 | 230 | 0.25 |
18. Tile and panel | 12.7 | 260 | 0.25 |
15 | 260 | 0.30 | |
19. Steel | 1 | 7 849 | 0.00002 |
20. Cardboard, pressed paperboard | 50 | 320 | 0.62 |
21. Fired clay tile | 16 (min) | 1 920 | 0.02 |
22. Cement tile | 16 (min) | 2 200 | 0.01 |
23. Hardwood | 19 | 870 | 0.10 |
24. Softwood | 12 | 520 | 0.11 |
19 | 520 | 0.17 | |
25. (Pine) rain and sun shading panel | 12 (trung bình) | 520 | 0.09 |
26. Pressed wood fiber, shavings board, sawdust | 50 | 520 | 0.61 |
Table F.6 – Thermal resistance of outdoor air layers
Wind speed | Surface location | Heat flow direction | Thermal resistance m2.K/W | |||
Surface with high diffusivity (clay tile) (ε = 0.9) | Galvanized steel flat roof (ε = 0.28) | Aluminum sheet roof (ε = 0.11) | Surface with low diffusivity (reflective metal sheet) (ε = 0.05) | |||
Air layer (Typical indoor surface) | Horizontal and slope > 45° | Upwar | 0.11 | 0.16 | 0.22 | 0.24 |
Horizontal and slope > 450 | Downward | 0.16 | 0.40 | 0.57 | 0.80 | |
Downward | 0.13 | – | – | 0.39 | ||
Vertical | Horizontal | 0.12 | – | – | 0.30 | |
0.5 m/s (typical indoor surface for airflow) | Any position | Any position | 0.08 | |||
From 3 m/s to 6 m/s (typical outdoor surface, windy) | Any position | Any position | from 0.04 to 0.03 |
Table F.7 – Thermal resistance of closed air layers
Air layer thickness (mm) | Heat transmission direction | |||||
Upward | Horizontal | Downward | ||||
m2.K/W | m2.h.K/kCal | m2.K/W | m2.h.K/kCal | m2.K/W | m2.h.K/kCal | |
0 | 0 | 0 | 0 | 0 | 0 | 0 |
5 | 0.11 | 0.13 | 0.11 | 0.13 | 0.11 | 0.13 |
7 | 0.13 | 0.15 | 0.13 | 0.15 | 0.13 | 0.15 |
10 | 0.15 | 0.17 | 0.15 | 0.17 | 0.15 | 0.17 |
15 | 0.16 | 0.19 | 0.17 | 0.20 | 0.17 | 0.20 |
25 | 0.16 | 0.19 | 0.18 | 0.21 | 0.19 | 0.22 |
50 | 0.16 | 0.19 | 0.18 | 0.21 | 0.21 | 0.24 |
100 | 0.16 | 0.19 | 0.18 | 0.21 | 0.22 | 0.26 |
300 | 0.16 | 0.19 | 0.18 | 0.21 | 0.23 | 0.27 |
NOTES:
– Thermal resistance for upward heat flow is for an average temperature difference of 10°C and a temperature difference of 5°C. Thermal resistance for downward heat flow is for an average temperature of 30°C and any temperature difference (for horizontal air layers), or for a temperature difference of 5°C (for air layers with a slope of 45°C);
– Dust will adhere to horizontal – vertical and inclined surfaces, the reflectance and diffusivity depend on the amount of suspended dust in the air and during the use of the building. The thermal resistance in Table D1 allows for the effect of dust, assuming that the surfaces are completely covered with dust and have an overall diffusivity of 0.82;
– For completely smooth surfaces, the thermal resistance can be determined by linear interpolation method.
Table F.8 – Thermal resistance of sloped attic spaces
Attic space ventilation | Thermal resistance m2.K/W | ||
Surface with high diffusivity | Surface with low diffusivity | ||
Upward heat flow | Ventilated | 0.11 | 0.34 |
Unventilate | 0.18 | 0.56 | |
Downward heat flow | Ventilated | 0.46 | 1.36 |
Unventilate | 0.28 | 1.09 |
Appendix H (Reference) Guidelines for using materials and colors in residential building surfaces
Climate – color – light in living rooms must create a feeling of thermal – psychological comfort and meet the needs of normal reading. It is necessary to functionally zone the work and determine the direction, type of lighting as well as the thermal – humidity characteristics of the room.
From the perspective of creating climate – color – light conditions for all rooms in a residential building, it can be divided into the following two types:
– Periodic color scheme: depending on the taste and preferences of the user, including living rooms, kitchen, bathroom, toilet;
– Non-mandatory color scheme: apartment lobby, apartment corridor, rooms outside the apartment.
The color of materials in general (including decorative materials) is characterized by the following parameters: λ (wavelength of the hue), ρ (brightness or clarity), P (saturation). The hue determines the color of the material and specifies the wavelength composition of the spectrum in nanometers (nm). The saturation P is defined as the percentage (%) of that color in the material composition. The brightness (clarity) ρ is determined by the color flux and is characterized by the reflectance as a percentage.
Based on the color-defining parameters (l; P; ρ), the entire color range is divided into 3 groups:
– Group I, including the middle wavelength range of the spectrum: Peaceful blue – Green; Sea blue – Green; Green, brown, yellow, yellow-brown λ from 490 nm to 586 nm; saturation P < 40%; color clarity coefficient ρ from 40% to 70%.
– Group II, the supplementary part of the entire range (diapason) with the supplementary groups of Red – Yellow and Peaceful blue λ from 469 nm to 520 nm; average saturation and brightness P ≤ 40%; color clarity coefficient ρ from 20% to 66%.
– Group III, the range of accentuated colors defined by the remaining frequency band of the spectrum from Coal purple to Vivid red with λ from 440 nm to 625 nm; average saturation and brightness P > 40%; color clarity coefficient ρ from 10% to 45%.
In rooms with periodic color schemes, the above 3 parameters are specified on the floor, ceiling, equipment surfaces, furniture.
Outside the apartment, it is necessary to determine the lighting level, which to some extent depends on the brightness of the surfaces. Therefore, the main rooms are determined according to the brightness index:
– The overall color tone of the room depends on the orientation of the window;
– Warm colors in the corresponding color group. If the window is facing South, Southeast, Southwest, it is necessary to use the basic cool color range. In the kitchen and bathroom, use cool or intermediate color ranges.
– Kitchen floor materials need to create thermal and acoustic comfort (use thermal and sound insulating materials).
– Wall sections and equipment at work areas (in front of work tables, washing areas, etc.) need to use finishing, cladding materials with high mechanical durability, chemical corrosion resistance, moisture resistance, heat resistance and create normal climate – color – light conditions for the room.
– The kitchen walls are made of moisture-resistant paperboard, synthetic paint and other surface-coated paints, walls from the floor base to the ceiling column (from 30 cm to 40 cm below the ceiling surface). Kitchen floor materials should be of the same color without decorative patterns. The color of the wall sections, columns should match the floor color.
– The reflectance under natural lighting conditions of living rooms is difficult to control the spectrum of the directed light sources, so it is necessary to adjust the glare of the living room surfaces by color (paint, brush, wallpaper), surface treatment, use of screens, curtains, etc. for shading. The living room surfaces should be used and treated to have the following reflectance:
+ Ceiling from 60% to 80%; Screens, curtains from 40% to 60%; Walls from 35% to 60%; Floor from 15% to 35%;
+ The glare ratio between ceiling, walls, floor is 10:7:3 (similar to the glare ratio of the model sky in the North of our country is 10:7:3)
Table H.1 – Guidelines for using materials corresponding to colors
Appendix I (Reference)
Table I.1 – Calculation parameters of thermal physical properties of building materials
Material name | γ Kg/m3 | Thermal conductivit λ W/m.K | Heat absorption coefficient S (24h cycle) W/m2.K | Specific heat kJ/kg.0K | Water vapor permeability coefficient β g/(m.h.Pa) |
1. Concrete | |||||
1.1. Reinforced concrete, gravel concrete, pebble concrete | 2 500 | 1.74 | 17.20 | 0.92 | 0.0000158* |
1.2. Lightweight aggregate concrete | |||||
– Expanded slag concrete | 2 000 | 0.77 | 10.54 | 0.96 | |
1 800 | 0.63 | 9.05 | 0.96 | ||
1 800 | 0.53 | 7.87 | 0.96 | ||
– Expanded ash slag concrete | 1 700 | 1.00 | 11.68 | 1.05 | 0.0000548* |
1 500 | 0.76 | 9.54 | 1.05 | 0.0009 | |
1 300 | 0.56 | 7.63 | 1.05 | 0.000105 | |
– Lightweight concrete, ash slag aggregates | 1 700 | 0.96 | 11.40 | 1.05 | 0.0000188 |
1 500 | 0.70 | 9.16 | 1.05 | 0.0000975 | |
1 300 | 0.57 | 7.78 | 1.05 | 0.000105 | |
1 100 | 0.44 | 6.30 | 1.05 | 0.000135 | |
– Expanded clay lightweight concrete | 1 600 | 0.84 | 10.36 | 1.05 | 0.0000315* |
1 400 | 0.70 | 8.93 | 1.05 | 0.000039* | |
1 200 | 0.53 | 7.25 | 1.05 | 0.0000405* | |
– Lightweight aggregate, lightweight gravel | 1 500 | 0.77 | 9.70 | 1.05 | 0.0000315* |
1 300 | 0.63 | 8.16 | 1.05 | 0.000039* | |
1 100 | 0.50 | 8.70 | 1.05 | 0.0000435* | |
– Lightweight aggregate concrete | 1 500 | 0.67 | 9.09 | 1.05 | |
1 300 | 0.53 | 7.54 | 1.05 | 0.0000188* | |
1 100 | 0.42 | 6.13 | 1.05 | 0.0000353* | |
1.3. Lightweight concrete | |||||
– Foam concrete | 700 | 0.22 | 3.56 | 1.05 | 0.0000998* |
500 | 0.19 | 2.76 | 1.05 | 0.000111* | |
2. Mortar and masonry units | |||||
2.1. Mortar | |||||
– Cement mortar | 1 800 | 0.93 | 11.26 | 1.05 | 0.000021* |
– Lime – cement – sand mortar (triple mix) | 1 700 | 0.87 | 10.79 | 1.05 | 0.0000975* |
1 600 | 0.81 | 10.12 | 1.05 | 0.0000443* | |
– Lime – sand mortar | 1 500 | 0.76 | 9.44 | 1.05 | |
– Lime, gypsum, sand mortar | 800 | 0.29 | 4.44 | 1.05 | |
– Insulating mortar | |||||
2.2. Masonry units | |||||
– Heavy mortar clay brick masonry | 1 800 | 0.81 | 10.53 | 1.05 | 0.000105* |
– Light mortar clay brick masonry | 1 700 | 0.76 | 9.86 | 1.05 | 0.00012 |
– Lime-sand masonry | 1 900 | 1.10 | 12.72 | 1.05 | 0.000105 |
– Silicate brick masonry | 1 800 | 0.87 | 11.11 | 1.05 | 0.000105 |
– Slag brick masonry | 1 700 | 0.81 | 10.39 | 1.05 | 0.000105 |
– Hollow clay brick masonry 26; 33 and 36 holes, heavy mortar | 1 400 | 0.58 | 7.52 | 1.05 | 0.0000158 |
3. Insulation material | |||||
3.1. Fibrous materials | |||||
– Mineral wool | < 150 | 0.064 | 0.93 | 1.22 | 0.000488 |
– Glass wool | from 150 to 300 | from 0.07 to 0.093 | from 0.98 to 1.60 | 1.22 | |
≤ 150 | 0.058 | 0.94 | 1.34 | 0.000488 | |
≤ 100 | 0.047 | 0.56 | 0.84 | 0.000488 | |
150 | 0.070 | 1.34 | 2.10 | ||
3.2. Expanded perlite, vermiculite products | |||||
– Expanded perlite cement | 800 | 0.26 | 4.16 | 1.17 | 0.000042* |
600 | 0.21 | 3.26 | 1.17 | 0.00009* | |
400 | 0.16 | 2.35 | 1.17 | 0.000191* | |
400 | 0.12 | 2.28 | 1.55 | 0.0000293* | |
– Bitumen, expanded perlite bitumen emulsion, expanded vermiculite cement | 300 | 0.093 | 1.77 | 1.55 | 0.0000675* |
350 | 0.14 | 1.92 | 1.05 | ||
3.3. Foam materials and mixed porous materials | |||||
– Mixed ethylene foam | 100 | 0.047 | 0.69 | 1.38 | |
30 | 0.042 | 0.35 | 1.38 | ||
– Mixed rigid ammoniac foam | 50 | 0.037 | 0.43 | 1.38 | |
40 | 0.033 | 0.36 | 1.38 | ||
– Soft foam | 130 | 0.048 | 0.79 | 1.38 | |
– Calcium plas | 120 | 0.049 | 0.83 | 1.59 | |
– Foam glass | 140 | 0.058 | 0.70 | 0.84 | 0.0000225 |
– Lime powder | 300 | 0.116 | 1.63 | 1.05 | |
400 | 0.14 | 2.06 | 1.05 | ||
– Foam gypsum | 500 | 0.19 | 2.65 | 1.05 | 0.0000375 |
4. Wood, building board materials | |||||
4.1. Wood | |||||
– Rubber wood, ironwood (cross grain) | 700 | 0.23 | 5.43 | 2.51 | 0.0000562 |
– Rubber wood, ironwood (longitudinal grain) | 700 | 0.41 | 7.18 | 2.51 | 0.0003 |
– Pine, palm, fir (cross grain) | 500 | 0.17 | 3.98 | 2.51 | 0.0000345* |
– Pine, palm, fir (longitudinal grain) | 500 | 0.35 | 5.63 | 2.51 | 0.000168 |
4.2. Building board materials | |||||
– Plywood | 600 | 0.17 | 4.36 | 2.51 | 0.0000225 |
– Soft wood board | 300 | 0.093 | 1.95 | 1.89 | 0.0000225* |
– Particle board | 1 500 | 0.058 | 1.09 | 1.89 | 0.0000285* |
– Insulating fiber cement board | 1 000 | 0.34 | 7.83 | 2.51 | 0.00012 |
600 | 0.23 | 5.04 | 2.51 | 0.000113 | |
– Cement-bonded wood shaving board | 1 800 | 0.52 | 8.57 | 1.05 | 0.0000135* |
500 | 0.16 | 2.48 | 1.05 | 0.00039 | |
– Compressed straw boar | 1 050 | 0.33 | 5.08 | 1.05 | 0.000079* |
– Compressed sawdust board | 1 000 | 0.34 | 7.00 | 2.01 | 0.000024* |
700 | 0.19 | 4.35 | 2.01 | 0.000105 | |
300 | 0.105 | 1.95 | 1.68 | 0.0003 | |
200 | 0.065 | 1.41 | 2.10 | 0.000263 | |
5. Loose materials | |||||
5.1. Inorganic materials | |||||
– Boiler slag | 1 000 | 0.29 | 4.40 | 0.92 | 0.0000193 |
– Coal ash powder | 1 000 | 0.23 | 3.93 | 0.92 | |
– Blast furnace slag | 900 | 0.26 | 3.92 | 0.92 | 0.000203 |
– Pumice | 600 | 0.23 | 3.05 | 0.92 | 0.000263 |
– Expanded vermiculite | 300 | 0.14 | 1.80 | 1.05 | |
200 | 0.10 | 1.28 | 1.05 | ||
– Porous soil | 200 | 0.076 | 1.00 | 0.92 | |
– Expanded perlite | 120 | 0.07 | 0.84 | 1.17 | |
80 | 0.058 | 0.63 | 1.17 | ||
5.2. Organic materials | |||||
– Sawdust | 250 | 0.093 | 1.84 | 2.01 | 0.000263 |
– Rice husk | 120 | 0.06 | 1.02 | 2.01 | |
– Dry grass | 100 | 0.047 | 0.83 | 2.01 | |
6. Other materials | |||||
6.1. Soil | |||||
– Compacted clay | 2 000 | 1.16 | 12.99 | 1.01 | |
– Clay mixed with grass | 1 800 | 0.93 | 11.03 | 1.01 | |
– Clay mixed with grass | 1 600 | 0.76 | 9.37 | 1.01 | |
– Light clay | 1 400 | 0.58 | 7.69 | 1.01 | |
– Construction sand | 1 200 | 0.47 | 6.36 | 1.01 | |
1 600 | 0.58 | 8.30 | 1.01 | ||
6.2. Stone | |||||
– Granite, basalt | 2 800 | 3.49 | 25.49 | 0.92 | 0.0000113 |
– Granite | 2 800 | 2.91 | 23.27 | 0.92 | 0.0000113 |
– Sandstone | 2 400 | 2.04 | 18.03 | 0.92 | 0.0000375 |
– Limestone | 2 000 | 1.15 | 12.56 | 0.92 | 0.00006 |
6.3. Rolled materials, bituminous materials | 600 | 0.17 | 3.33 | 1.46 | |
– Oiled paper | 2 100 | 1.05 | 16.31 | 1.68 | 0.0000075 |
– Asphalt concrete | 1 400 | 0.27 | 6.73 | 1.68 | |
– Petroleum bitumen | 1 050 | 0.17 | 4.71 | 1.68 | 0.0000075 |
6.4. Glass | |||||
– Flat sheet glass | 2 500 | 0.76 | 10.69 | 0.84 | |
– Wired glass | 1 800 | 0.52 | 9.25 | 1.26 | |
6.5. Metals | |||||
– Brass | 8 500 | 407 | 323.5 | 4.2 | |
– Bronze | 8 000 | 64.9 | 118.0 | 3.7 | |
– Structural steel | 7 850 | 58.2 | 126.1 | 4.8 | |
– Aluminum | 2 700 | 203 | 191.0 | 9.2 | |
– Cast iron | 7 250 | 49.9 | 112.2 | 4.8 | |
NOTES: 1) Under normal conditions of use in cold and hot humid regions, the thermal physical properties of materials can be used directly according to Table M.1; 2) Under conditions of use different from Table M.1, the calculated value of the thermal conductivity of the material is adjusted according to the formula: λc = λ.a; Where: λ– Thermal conductivity of the material, according to Table M.1; a– Correction factor, according to Table M.2 considering the condition of the material. The heat storage coefficient is adjusted according to the formula: Sc = S.a Where: S- Heat storage coefficient of the material, according to Table M.1; a– Correction factor, according to Table M.2. 3) In dry regions such as the Northwest, etc., the calculated thermal conductivity of heavy mortar clay brick masonry is allowed to use λ = 0.76 W/(m.°K); the calculated heat storage coefficient is allowed to use S = 10.16 W/(m2.°K); the calculated thermal conductivity of light mortar clay brick masonry is allowed to take λ = 0.70 W/(m.°K), the calculated heat storage coefficient is allowed to take S = 9.47 W/(m2.°K); 4) In practice, the specific heat unit c is usually taken as W.h(kg.°K), so the specific heat values in Table L.1 should be multiplied by the conversion factor 0.2778; 5) The numbers marked with * in Table L.1 are the measured values determined at a test temperature of about 20°C, without deducting the influence of the water vapor permeation resistance of the boundary layer on both sides. |
Table I.2 – Correction factor a for calculating thermal conductivity λ and heat storage coefficient S
Material, structure, construction area and usage conditions | a |
1. Porous insulating materials in slab form used as core layer in concrete walls and concrete roof components (such as aerated concrete, foam concrete, etc.) due to slow drying. | 1.7 |
2. Porous insulating materials filled in closed roofs (such as aerated concrete, foam concrete, boiler slag, etc.) due to slow drying. | 1.5 |
3. Semi-rigid materials such as mineral wool, rock wool, glass wool, etc. filled in closed roofs and used as core layer in concrete components due to compression and moisture absorption. | 1.5 |
4. Foam plastics, etc. used as core layer in concrete components, due to compression. | 1.3 |
5. Porous insulating materials (such as cement-bonded wood shaving boards, wood fiber boards, straw boards, etc.) plastered on the surface and cast together with concrete, due to mortar penetration. | 1.3 |
6. Walls built with aerated concrete blocks, foam concrete blocks and walls, roofs made of aerated concrete slabs. | 1.25 |
7. Loose insulating materials (such as rice husk, sawdust, mineral wool, etc.) stuffed in hollow walls and roof components, due to settling. | 1.2 |
8. Solid walls and roof components made of ore slag concrete, coal slag concrete, porous gravel concrete, porous ceramic concrete, coal ash concrete, aerated concrete, etc. In heated rooms with an average indoor relative humidity above 65% and in cold regions, due to slow drying. | 1.15 |
Table I.3 – Moisture resistance Hc of commonly used thin sheet materials and layers
Name of material and coating layer | Thickness (mm) | Hc (m2.h.Pa/g) |
1. Ordinary pressed paperboard | 1 | 16.0 |
2. Gypsum board | 8 | 120.0 |
3. Hard pressed wood fiberboar | 8 | 106.7 |
4. Soft pressed wood fiberboard | 10 | 53.3 |
5. 3-layer plywood | 3 | 220.6 |
6. Fiber cement board | 6 | 260.6 |
7. Hot bitumen 1 coat | 2 | 266.6 |
8. Hot bitumen 2 coa | 4 | 480 |
9. Bitumen emulsion 2 coats | – | 520 |
10. Gas-divergent ethylene 2 coats | – | 1 239 |
11. Nutrient ink 2 layers | – | 3 733 |
12. Paint 2 layers (fill cracks with putty first, then apply primer) | – | 639.3 |
13. Coating layer | – | 3 368.3 |
14. Chlorinated rubber coating 2 layers | – | 3 466.3 |
15. Petroleum bitumen asphalt carpet | 1.5 | 1 198.3 |
16. Petroleum bitumen oiled paper | 0.40 | 293 |
17. Thin film | 0.18 | 733 |
BIBLIOGRAPHY OF REFERENCES
[1] QCVN 02: 2009/BXD – Vietnam Construction Code. Natural condition data used in construction (part 1)
[2] QCVN 01: 2008/BXD – Vietnam Construction Code on construction planning1. The TCXDs and TCXDVNs are being converted to TCVNs