The building envelope, also known as the building enclosure, includes opaque or transparent walls and roofs (glass walls, windows, etc.) that form enclosed spaces inside the building.
The ratio of output energy (useful energy at the time of use) to input energy with the same unit of measurement for a specified period, expressed as a percentage;
The steady-state heat flow rate per unit area through a building envelope component when the air temperature difference between the environments on both sides of the component is 1 K, unit of measurement W/(m2.K);
The total heat transmitted into the building through the entire surface area of the building envelope, including both the opaque walls and windows, expressed per 1 m2 of the exterior surface of the building, W/m2;
The ratio of heating capacity obtained to the electrical input power on the same unit of measurement, calculated for the entire heat pump system under design operating conditions;
The ratio of cooling capacity obtained to the electrical input power on the same unit of measurement. The COP value is determined to evaluate the energy efficiency of electrically-driven air conditioners, air-cooled condensing, including compressors, evaporator coils, and condenser coils. The COP value is also determined to evaluate the energy efficiency of packaged water chillers (excluding chilled water pumps, condenser water pumps, and cooling tower fans);
A coefficient for evaluating the aerodynamic quality of a fan, which is the ratio of air power at the fan outlet to the useful power of the motor acting on the fan shaft;
QCVN 09:2017/BXD “National Technical Regulation on Energy Efficiency Buildings” was reviewed by the Institute of Construction Technology (Vietnam Association of Construction Structure and Technology) based on QCVN 09:2013/BXD, submitted for approval by the Department of Science, Technology, and Environment, and promulgated by the Ministry of Construction under Circular No. 15/2017/TT-BXD dated December 28, 2017.
Regulation QCVN 09:2017/BXD replaces QCVN 09:2013/BXD “National Technical Regulation on Energy Efficiency Buildings” issued under Circular No. 15/2013/TT-BXD dated September 26, 2013 by the Minister of Construction.
This regulation was compiled with the support of the Government of Denmark and the participation of experts from the Vietnam Green Building Council, International Finance Corporation (IFC), Pacific Northwest National Laboratory (PNNL, U.S. Department of Energy).
1. GENERAL PROVISIONS
1.1 Scope of regulation
1.1.1 The national technical regulation on energy efficiency buildings stipulates the mandatory technical requirements to be complied with in the design, new construction, or renovation of buildings with a total floor area of 2500 m2 or more belonging to the following types or a combination of the following types of buildings:
Offices;
Hotels;
Hospitals;
Schools;
Commercial and service buildings;
Apartment buildings.
1.1.2 The provisions in this regulation are applied to the following parts:
Building envelope;
Ventilation and air-conditioning system;
Lighting system;
Other electrical equipment (electric motors; hot water supply system).
NOTE: When renovating buildings within the scope of this Regulation, the provisions on the building envelope, ventilation and air-conditioning system, lighting system, and other electrical equipment are applied to the corresponding renovated parts.
1.2 Subjects of application
This regulation applies to all organizations and individuals engaged in the construction of buildings within the scope of this Regulation.
1.3 References
The following references are essential when applying this Regulation. For standards without a specified year or standards with a specified year that have been reviewed and revised, the latest version shall be applied.
QCXDVN 05:2008/BXD
Vietnam Building Code. Housing and public buildings. Health and safety;
QCVN 12:2014/BXD
National technical regulation on electrical systems of residential and public buildings;
AMCA 205
Energy efficiency classification for fans;
ANSI Z21.10.3
Gas Water Heater, Volume 3, Storage, with Input Ratings above 75,000 Btu/h, Circulating and Instantaneous Water Heaters;
ARI 210/240
Performance rating of unitary air-conditioning and air-source heat pump equipment;
ARI 340/360
Performance rating of commercial and industrial unitary air-conditioning and heat pump equipment;
ARI 365
Commercial and industrial unitary air-conditioning condensing units;
ARI 550/590
Performance rating of water-chilling packages using the vapor compression cycle;
ARI 560-2000
Absorption water chilling and water heating packages;
ASHRAE 90.1 – 2016
Energy standard for buildings except low-rise residential buildings;
NEMA MG 1-2016
Motors and generators;
NFRC 200-2017
Procedure for determining fenestration product Solar Heat Gain Coefficients and Visible Transmittance at normal incidence;
ISO 6946-2017
Building components and building elements. Thermal resistance and thermal transmittance. Calculation method;
ISO 10456-2007
Building materials and products – Hygrothermal properties – Tabulated design values and procedures for determining declared and design thermal values;
ISO 12759:2010
Fans. Efficiency classification for fans;
TCVN 4605:1988
Thermal engineering. Building envelope. Design standard
TCVN 5687:2010
Ventilation and air conditioning. Design standard;
TCVN 6307:1997 (ISO 916:1968)
Refrigerating systems. Testing methods;
TCVN 6576:2013 (ISO 5151:2010)
Non-ducted air conditioners and heat pumps – Testing and rating for performance;
TCVN 7540:2013
Three-phase cage induction motors. Part 1 – Energy efficiency (TCVN 7540-1:2013); Part 2 – Methods for determining energy efficiency (TCVN 7540-2:2013);
TCVN 7830:2015
Non-ducted air conditioners – Energy efficiency;
TCVN 9258:2012
Thermal insulation for housing. Design guidelines;
TCVN 10273-1:2013 (ISO 16358-1:2013)
Air-cooled air conditioners and air-to-air heat pumps – Testing and calculating methods for seasonal efficiency factors. Part 1: Seasonal cooling efficiency ratio.
1.4 Definitions and symbols
1.4.1 Definitions
1) Fan Efficiency Grade (FEG): A coefficient for evaluating the aerodynamic quality of a fan, which is the ratio of air power at the fan outlet to the useful power of the motor acting on the fan shaft;
2) Coefficient of Performance (COP), kW/kW: The ratio of cooling capacity obtained to the electrical input power on the same unit of measurement. The COP value is determined to evaluate the energy efficiency of electrically-driven air conditioners, air-cooled condensing, including compressors, evaporator coils, and condenser coils. The COP value is also determined to evaluate the energy efficiency of packaged water chillers (excluding chilled water pumps, condenser water pumps, and cooling tower fans);
3) Heat pump COP, kW/kW: The ratio of heating capacity obtained to the electrical input power on the same unit of measurement, calculated for the entire heat pump system under design operating conditions;
4) Overall Thermal Transfer Value (OTTV): The total heat transmitted into the building through the entire surface area of the building envelope, including both the opaque walls and windows, expressed per 1 m2 of the exterior surface of the building, W/m2;
5) Thermal Transmittance (U0): The steady-state heat flow rate per unit area through a building envelope component when the air temperature difference between the environments on both sides of the component is 1 K, unit of measurement W/(m2.K);
6) Thermal Resistance (R0): R0 = 1/U0, unit of measurement m2.K/W;
7) Lamp efficacy: The ratio between the luminous flux of a lamp and the electrical power of the lamp, measured in lm/W;
8) Efficiency of ventilation and air-conditioning system: The ratio of output energy (useful energy at the time of use) to input energy with the same unit of measurement for a specified period, expressed as a percentage;
9) Lighting Power Density (LPD): The lighting power density is the ratio of the electrical power for lighting to the illuminated area, W/m2;
10) Building Envelope: The building envelope, also known as the building enclosure, includes opaque or transparent walls and roofs (glass walls, windows, etc.) that form enclosed spaces inside the building.
1.4.2 Symbols, units of measurement, and abbreviations
1) Symbols, units of measurement
SHGC
Solar Heat Gain Coefficient, published by the manufacturer or determined according to current standards, dimensionless. If the manufacturer uses the shading coefficient, then SHGC = SC x 0.86;
SC
Shading Coefficient;
R0
Thermal Resistance of the building envelope, m2.K/W. Thermal TransmittanceU0=1/R0, W/(m2.K);
OTTVT
Overall Thermal Transfer Value through walls – The average heat flow intensity transmitted through 1 m2 of exterior wall into the building, W/m2;
OTTVM
Overall Thermal Transfer Value through roofs – The average heat flow intensity transmitted through 1 m2 of roof structure into the building, W/m2;
WWR
Window to Wall Ratio, expressed as a percentage (%).
2) Abbreviation
AHU
Air Handling Unit;
AMCA
Air Movement and Control Association International, Inc.;
ANSI
American National Standards Institute;
ARI
Air Conditioning and Refrigeration Institute;
ASHRAE
American Society of Heating, Refrigerating and Air Conditioning Engineers;
ASME
American Sociaty of Mechanical Engineers;
HVAC
Heating, Ventilation and Air Conditioning;
NEMA
National Electric Manufacturers Association;
NFRC
National Fenestration Rating Council, Inc.;
ISO
International Organization for Standardization;
QCVN
National Technical Regulation;
TCVN
National Standard.
2. TECHNICAL PROVISIONS
2.1 Building envelope
2.1.1 The technical provisions for the building envelope only apply to air-conditioned spaces.
2.1.2 Requirements for exterior walls and roofs of buildings
Requirements for the total thermal resistance R0 of the opaque part:
– The above-ground exterior walls (opaque wall parts) of air-conditioned spaces must have a minimum total thermal resistance value R0.min not less than 0.56 m2.K/W;
– Flat roof structures and roofs with a slope below 15° directly above air-conditioned spaces must have a total thermal resistance value R0.min not less than 1.00 m2.K/W.
NOTES:
– Flat roofs with reflective materials: The thermal resistance value R0.min can be multiplied by a factor of 0.80 for roofs designed with reflective materials having a reflectance in the range of 0.70-0.75 to increase the reflectance of the exterior roof surface (Appendix 5);
– Roofs with a slope of 15° or more: The minimum total thermal resistance of the roof can be determined by multiplying the R0.min values by a factor of 0.85;
– Roof structures not required to comply with section 2.1.2: More than 90% of the roof surface is shaded by a fixed ventilated shading structure. The shading structure must be at least 0.3 m from the roof surface to be considered as having ventilation between the roof layer and the shading layer for the roof (double-layer roof with a convective air layer in between).
Requirements for the transparent part (windows, glass walls):
– The maximum SHGC value of glass walls and windows is determined separately for each wall surface according to the North, South (North and South directions with a deviation range of ± 22.5° from the main North or South axis), other directions, and must satisfy the values in table 2.1.
Table 2.1 – SHGC of glass depending on the WWR ratio
WR (%)
SHGC
North
South
Other directions
20
0,90
0,90
0,80
30
0,64
0,70
0,58
40
0,50
0,56
0,46
50
0,40
0,45
0,38
60
0,33
0,39
0,32
70
0,27
0,33
0,27
80
0,23
0,28
0,23
90
0,20
0,25
0,20
100
0,17
0,22
0,17
NOTES: – WWR is calculated for each vertical surface, then averaged for the entire building; – When WWR falls between the values listed in the table, linear interpolation of SHGC is allowed; – The SHGC value of each vertical surface or of the entire building can be determined by the Area-Weighted Average value of the transparent parts on the vertical surface of the building: where: SHGCi, Ai are the SHGC value and area of the transparent part i (i = 1, n).
The maximum SHGC value for skylights is 0.3. For attic spaces using daylight, the maximum SHGC of skylights is allowed to be 0.6;
In case the building facade has continuous vertical or horizontal shading structures, the SHGC coefficient in table 2.1 can be adjusted by multiplying by factor A in Table 2.2a or 2.2b;
Table 2.2a – Factor A for fixed horizontal shading structures
Ratio PF=b/H
Factor A
North
South
Other directions
0,1
1,23
1,20
1,09
0,2
1,43
1,39
1,19
0,3
1,56
1,39
1,30
0,4
1,64
1,39
1,41
0,5
1,69
1,39
1,54
0,6
1,75
1,39
1,64
0,7
1,79
1,39
1,75
0,8
1,82
1,39
1,85
0,9
1,85
1,39
1,96
1,0
1,85
1,39
2,08
NOTES: – PF (Projection Factor) = b/H, with dimensions b being the projection of the shading structure from the glass plane; H is the window height measured from the bottom of the window to the underside of the shading structure. The dimensions b and H have the same unit; – Continuous horizontal shading structure, placed at a distance d from the top edge of the window with d/H ≤ 0.1 (calculation error 10%).
Table 2.2b – Factor A for fixed vertical shading structures
Ratio PF=b/B
Factor A
North
South
Other directions
0,1
1,25
1,11
1,01
0,2
1,52
1,19
1,03
0,3
1,75
1,22
1,05
0,4
1,82
1,25
1,06
0,5
1,85
1,28
1,09
0,6
1,85
1,30
1,10
0,7
1,89
1,30
1,12
0,8
1,89
1,30
1,14
0,9
1,89
1,30
1,16
1,0
1,89
1,30
1,18
NOTES: – PF (Projection Factor) = b/B, with dimensions b being the projection of the shading structure from the glass plane; B is the window width measured from the side edge of the window to the inside of the shading structure. The dimensions b and B have the same unit; – Continuous vertical shading structure, placed at a distance e from the side edge of the window with e/B ≤ 0.1 (calculation error 10%).
– For buildings adjacent to streets, the ground floor space designed with the function of displaying products, promoting services and goods, it is allowed not to comply with the SHGC requirements when satisfying all of the following conditions:
(a) The height of the ground floor does not exceed 6m;
(b) Continuous shading structure with b/H > 0.5; (c) The area of glass walls and windows is less than 75% of the total wall area of the ground floor on the street side.
If the above detailed provisions on R0 and SHGC are not applied, it is allowed to determine the Overall Thermal Transfer Value (OTTV) of the opaque and transparent building envelope structures and their values are specified as follows:
– OTTVT of walls does not exceed 60 W/m2;
– OTTVM of roofs does not exceed 25 W/m2.
NOTE: The OTTVT value of walls and OTTVM value of roofs are determined according to technical standards and guidelines.
2.1.3 Requirements for construction products and installation for walls and roofs of buildings
The thermal conductivity λ of materials, the total thermal resistance value R0 of walls and roofs are determined according to the standard ISO 6946:2017 or according to the guidelines in Appendices 1, 2, 3, 4, 6 of this Regulation;
NOTE: The thermal conductivity λ of materials is provided by the manufacturer or applies data according to the standards TCVN 4605:1988, TCVN 9258:2012.
Certification of SHGC testing for windows and glass walls must be provided by the manufacturer. The SHGC value of windows and glass walls is determined according to the standard NFRC 200-2017 by independent laboratories.
2.2 Ventilation and air conditioning
2.2.1 Natural ventilation
The area of vent openings, operable windows on walls or roofs must not be less than 5% of the usable area (floor) of the room adjacent to the outside space.
Natural ventilation or combined with mechanical ventilation of parking areas (garages) must meet the requirements of Regulation QCXDVN 05:2008/BXD.
2.2.2 Mechanical ventilation
The ventilation requirements according to Regulation QCXDVN 05:2008/BXD must be ensured.
Fans with motor power greater than 0.56 kW must have automatic control devices to allow turning off the fan when there is no demand for use.
NOTE: Except for fans in HVAC systems that operate continuously.
2.2.3 Air conditioning system
Air conditioning equipment and water chillers must have a minimum COP efficiency at standard rating conditions and not less than the values listed in Table 2.3, Table 2.4.
Table 2.3 – COP efficiency of direct cooling air conditioners powered by electricity
Equipment type
Cooling capacity, kW
COPMin, kW/kW
Testing procedure
Single-package air conditioners
–
2,80(*)
TCVN 6576:2013TCVN 7830:2015TCVN 10273-1:2013
Split-system air conditioners
< 4,5
3,10(*)
≥ 4,5 and < 7,0
3,00(*)
≥ 7,0 and < 12,0
2,80(*)
Air-cooled air conditioners
≥ 14 and < 19
3,81
TCVN 6307:1997 hoặc ARI 210/240
≥ 19 and < 40
3,28
ARI 340/360
≥ 40 and < 70
3,22
≥ 70 and <223
2,93
≥ 223
2,84
Water-cooled air conditioners
< 19
3,54
ARI 210/240
≥ 19 and < 40
3,54
ARI 340/360
≥ 40 and < 70
3,66
≥ 70 and < 223
3,63
≥ 223
3,57
Evaporatively-cooled air conditioners
< 19
3,54
ARI 210/240
≥ 19 and < 40
3,54
ARI 340/360
≥ 40 and < 70
3,51
≥ 70 and < 223
3,48
≥ 223
3,43
Air-cooled condensing units
≥ 40
3,07
ARI 365
Water-cooled or evaporatively-cooled condensing units
≥ 40
3,95
NOTES: COP = Cooling capacity / Electrical power input, kW/kW. Condensing unit includes compressor and condenser; (*) Single-package or split-system air conditioners: the energy efficiency of the equipment is evaluated by the Cooling Seasonal Performance Factor (CSPF) instead of COP. The testing procedure and energy efficiency evaluation of the equipment is performed according to TCVN 7830:2015, TCVN 6576:2013 and TCVN 10273-1:2013 (ISO 5151:2000).
Table 2.4 – COP efficiency of water chillers
Equipment type
Cooling capacity, kW
COPMin, kW/kW
Air-cooled chiller, electric. Attached or detached condenser
All
2,80
Reciprocating water-cooled chiller, electric
According to the requirements of Screw and Rotary water-cooled chillers, electric
Screw and Rotary water-cooled chillers, electric
< 264
4,51
≥ 264 and < 528
4,53
≥ 528 and < 1055
5,17
≥ 1055
5,67
Centrifugal water-cooled chillers, electric
< 528
5,55
≥ 528 and < 1055
5,55
≥ 1055 and < 2110
6,11
≥ 2110
6,17
Air-cooled absorption chillers, single-stage
All
0,60(*)
Double-stage hot water absorption chillers
All
0,70(*)
Double-stage indirect-fired absorption chillers
All
1,00(*)
Double-stage direct-fired absorption chillers
All
1,00(*)
NOTES: (*) For absorption chillers, COP = Cooling capacity / Heat input; Evaluation of absorption chiller performance uses the ARI 560 standard; Performance of water-cooled packages is evaluated by the ARI 550/590 standard.
Water chillers, steam generators, cooling tower fans, pumps with power greater than or equal to 5 horsepower (3.7 kW) must have automatic devices to adjust capacity and flow according to the demand for cooling, heating, and water.
Fan motors of ventilation and air conditioning systems with power greater than or equal to 5 horsepower (3.7 kW) must have an efficiency grade greater than FEG 67 when determined according to the AMCA 205 standard.
NOTE: The ISO 12759:2010 standard can be applied.
Buildings using central air conditioning systems must have cooling recovery devices. The minimum cooling recovery efficiency of the device is 50%.
Materials and insulation thickness for refrigerant pipes, chilled water pipes, air supply and return ducts must be designed, installed and accepted according to the technical standards selected to be applied to the building.
NOTE: Technical standards are selected by the investor to be applied. Technical standards TCVN 5687:2010, ASHRAE 90.1 and other equivalent technical standards are applied.
The COP efficiency indices (or Cooling Seasonal Performance Factor CSPF) listed in Tables 2.3, Table 2.4, and the fan efficiency grade FEG must be tested by independent laboratories. The manufacturer must provide test certificates for the technical specifications of the devices in the air conditioning system before accepting and installing them in the building.
2.3 Lighting
2.3.1 Natural lighting
In offices, classrooms, and library reading rooms with natural lighting, there must be solutions to adjust artificial lighting.
NOTE: Lighting control requirements for daylight zones do not apply to healthcare facilities, apartments, or buildings with special usage requirements.
2.3.2 Artificial lighting
The minimum illuminance requirements in residential and public buildings must comply with the National Technical Regulation QCVN 12:2014/BXD.
The lighting power density LPD for the interior of buildings must not exceed the maximum allowable levels listed in Table 2.5.
Table 2.5 – Lighting power density LPD
Building type
LPD (W/m2)
Office
11
Hotel
11
Hospital
13
Medical station, health care*
11
Library*
14
Conference*
15
School
12
Commercial, service
16
Apartment building
8
Warehouse*
9
Indoor parking area
3
NOTES: – (*) The items are part of the building types within the scope of this Regulation; – Lighting power density LPD is calculated by the total designed lighting power divided by the total usable floor area; – For buildings including many types of functions (mixed-use buildings): LPD is determined according to the lighting power and usable floor area for each type; – For areas or parts with special lighting requirements in educational and medical facilities: LPD is taken according to the design standards applied; – For apartment buildings, instead of applying the LPD regulations in the table, energy-labeled lighting devices must be used according to current regulations.
Lighting control
a) Lighting control
– Devices to turn off lighting when not needed must be designed and installed for areas with a maximum area of 2500 m2 on one floor;
– Each lighting control device is designed and installed for a usable area of maximum 250 m2 for areas up to 1000 m2 and maximum 1000 m2 for areas larger than 1000 m2.
NOTE: This regulation does not apply to spaces requiring 24/24 h lighting; spaces requiring security and safety during use.
b) Lighting control for indoor parking areas (garages)
– Automatic lighting shutoff (see above);
– There must be lighting control devices that allow reducing at least 30% of the lighting power of each light source when there is no activity in the illuminated area;
NOTE: This requirement does not apply to entrance and exit areas adjacent to the outside of the building.
– For areas within 6 m of the outer walls, with doors and glass walls with WWR ratio ≥ 40%, there must be control devices that allow reducing the lighting power.
2.4 Other electrical equipment
Electric motors
a) Three-phase electric motors (50 Hz) manufactured independently or as part of equipment installed for construction works must have a minimum efficiency at full load not less than the values listed in Table 2.6.
b) The manufacturing label on the electric motor housing must have the value of the minimum efficiency at full load. The efficiency of electric motors must be determined in accordance with the NEMA MG-1 standard.
NOTE: The TCVN 7540-2:2013 standard or other equivalent standards selected to be applied.
c) When installing, inspecting and accepting electric motors for construction works according to current regulations, it is necessary to check the minimum efficiency of the electric motor stated on the housing by the manufacturer.
Table 2.6 – Minimum efficiency of electric motors at full load
Motor output power, kW
Open type motor
Enclosed type motor
2 poles
4 poles
6 poles
2 poles
4 poles
6 poles
Speed (rpm)
3600
1800
1200
3600
1800
1200
0,8
77,0
85,5
82,5
77,0
85,5
82,5
1,1
84,0
86,5
86,5
84,0
86,5
87,5
1,5
85,5
86,5
87,5
85,5
86,5
88,5
2,2
85,5
89,5
88,5
96,5
89,5
89,5
3,7
86,5
89,5
89,5
88,5
89,5
89,5
5,6
88,5
91,0
90,2
89,5
91,7
91,0
7,5
89,5
91,7
91,7
90,2
91,7
91,0
11,1
90,2
93,0
91,7
91,0
92,4
91,7
14,9
91,0
93,0
92,4
91,0
93,0
91,7
18,7
91,7
93,6
93,0
91,7
93,6
93,0
22,4
91,7
94,1
93,6
91,7
93,6
93,0
29,8
92,4
94,1
94,1
92,4
94,1
94,1
37,3
93,0
94,5
94,1
93,0
94,5
94,1
44,8
93,6
95,0
94,5
93,6
95,0
94,5
56,0
93,6
95,0
94,5
93,6
95,4
94,5
74,6
93,6
95,4
95,0
94,1
95,4
95,0
93,3
94,1
95,4
95,0
95,0
95,4
95,0
111,9
94,1
95,8
95,4
95,0
95,8
95,8
149,2
95,0
95,8
95,4
95,4
96,2
95,8
186,5
95,0
95,8
95,4
95,8
96,2
95,8
223,8
95,4
95,8
95,4
95,8
96,2
95,8
261,1
95,4
95,8
95,4
95,8
96,2
95,8
298,4
95,8
95,8
95,8
95,8
96,2
95,8
357,7
95,8
96,2
96,2
95,8
96,2
95,8
373,0
95,8
96,2
96,2
95,8
96,2
95,8
Hot water system
a) Efficiency of hot water equipment
– All hot water equipment and boilers supplying hot water used for construction works must have minimum efficiency as in Table 2.7;
– Heat pumps for hot water supply must achieve minimum COP efficiency as in Table 2.8;
– When using a solar hot water system, the minimum efficiency of the solar hot water tank is 60% and the minimum thermal resistance R0 value of the back of the solar energy absorber is 2.2 m2.K/W.
Table 2.7 – Minimum efficiency of hot water equipment
Equipment type
Minimum efficiency ET, %
Gas water heaters, storage type
78
Gas-fired instantaneous water heaters
78
Gas-fired water supply boilers
77
Oil-fired water supply boilers
80
Gas and oil-fired water supply boilers
80
Boilers with thermal capacity of 10-350 kW, burning wood, paper
60
Boilers with thermal capacity of 10-2000 kW, burning brown coal
70
Boilers with thermal capacity of 10-2000 kW, burning anthracite coal
73
Electric resistance water heaters
Emin = 5,9 + 5,3V0,5 (W)
NOTES: – The minimum efficiency of gas or oil-fired water heaters is given in the form of thermal efficiency ET, which includes heat loss from the compartments of the heater; – The minimum efficiency of electric resistance water heaters is determined from the maximum standby loss (SL) when the temperature difference between the heated water and the surrounding environment is 40°C. In the above formula, V is the volume measured in liters; – The test procedure is carried out according to the ANSI Z21.10.3 standard or other standards applied to the construction works.
Table 2.8 – Minimum COP efficiency of heat pumps for hot water supply
Equipment type
COP, kW/kW
Heat pumps with heat source from air
≥ 3,0
Heat pumps with heat source from water
≥ 3,5
Air conditioners with heat recovery: When running to supply hot water When running air conditioning and supplying hot water
≥ 3,0≥ 5,5
b) Before installing the water heater, the efficiency of the equipment provided by the manufacturer must be checked.
c) Insulation for hot water pipes must be designed, installed and accepted according to the design standards applied to the construction works.
d) Control of hot water system
– Temperature control systems are installed to limit the hot water temperature at the time of use not to exceed 49°C;
– Temperature control systems are installed to limit the maximum water temperature supplied to the faucets in bathtubs and sinks in public bathrooms not to exceed 43°C;
– Circulation pumps used to maintain temperature in hot water tanks are controlled to operate in accordance with the operating mode of the hot water supply equipment.
e) For apartment buildings with centralized hot water supply systems designed and installed, renewable energy (solar energy, wind energy, heat recovery, etc.) must be used to supplement the energy source for hot water supply.
3. MANAGEMENT PROVISIONS
3.1 Design documents of new construction works, renovation and repair works within the scope of this regulation must include an explanation of compliance with the provisions of this regulation.
3.2 Appraisal and evaluation of design documents, construction and acceptance of construction works according to current regulations, including the regulation QCVN 09:2017/BXD.
4. IMPLEMENTATION
4.1 The Department of Science, Technology and Environment (Ministry of Construction) is responsible for organizing the dissemination and guidance on the application of QCVN 09:2017/BXD for relevant entities.
4.2 State management agencies at all levels in construction are responsible for organizing the inspection of compliance with the National Technical Regulation QCVN 09:2017/BXD in construction investment activities under their management responsibility according to current regulations.
4.3 During the implementation process, if there are any problems, all opinions should be sent to the Department of Science, Technology and Environment (Ministry of Construction) for guidance and handling.
Appendix 1. Total thermal resistance R0 of the building envelope
Formula for determining the total thermal resistance R0
(m2.K/W)
where:
hN, hT
Are the external and internal surface heat transfer coefficients of the building envelope structure (Appendix 3), respectively, W/(m2.K);
bi
Thickness of the i-th material layer, m;
λi
Thermal conductivity of the i-th material layer in the building envelope structure (Appendix 2), W/m.K;
n
Number of material layers of the building envelope structure;
Ra
Thermal resistance of the air layer inside the building envelope structure, if any (Appendix 4), m2.K/W.
Physical parameters of materials (Appendices 2, 3, 4)
Appendix 2. Thermal conductivity of building materials (For reference)
Material name
Unit weight, kg/m3
Thermal conductivit, W/(m.K)
1. Concrete
Reinforced cement tile
2500
2,04
Reinforced concrete
2400
1,55
Heavy concrete
2200
1,20
Lightweight concrete (slag concrete)
1500
0,70
1200
0,52
1000
0,41
Hot steam foam concrete
1000
0,40
800
0,29
600
0,21
400
0,15
Hot steam silicate foam concrete
800
0,29
600
0,21
400
0,15
2. Gypsum
Gypsum wall panel
1000
0,23
Furnace slag gypsum concrete
1000
0,37
3. Fired materials, mortar
Fired clay brick
2000
0,93
Fired clay brick
1600
0,70
Fired clay brick with heavy mortar
1800
0,81
Fired clay brick with lightweight mortar
1700
0,76
Hollow brick (1300 kg/m3) with lightweight mortar (1400 kg/m3)
NOTES: – Unit W/(m.K) = 0.86 kcal/m.h.°C; – The thermal conductivity of materials can be used according to test results; or data in the technical standard ISO 10456:2007.
Appendix 3. Surface heat transfer coefficients of the building envelope structure (For reference)
Coefficient name
Heat flow direction
Horizontal (for walls)
Upward (for roofs)
Downward (for roofs)
External surface heat transfer coefficient hN, W/(m2.K)
25
25
25
Internal surface heat transfer coefficient hT, W/(m2.K)
7,692
10
5,882
NOTE: See ISO 6946:2007 standard.
Appendix 4. Thermal resistance of unventilated air layer Ra, (m2.K/W) (For reference)
Air layer thickness, mm
Heat flow direction
Horizontal (for vertical air layer)
Upward (for horizontal air layer)
Downward (for horizontal air layer)
0
0,00
0,00
0,00
5
0,11
0,11
0,11
7
0,13
0,13
0,13
10
0,15
0,15
0,15
15
0,17
0,16
0,17
25
0,18
0,16
0,19
50
0,18
0,16
0,21
100
0,18
0,16
0,22
300
0,18
0,16
0,23
NOTE: See ISO 6946:2007 standard.
Appendix 5. Radiation absorption coefficient of material surfaces (For reference)
No.
Material, surface, and color
Coefficient α
A. Wall surfaces
1
Polished light-colored limestone
0,35
2
Polished dark-colored limestone
0,50
3
Polished white marble
0,30
4
Polished dark marble
0,65
5
Polished light gray granite
0,55
6
Polished gray granite
0,60
7
White ceramic tiles
0,26
8
Light brown ceramic tiles
0,55
9
Ordinary brick, dirty
0,77
10
Ordinary brick, new red
0,7 – 0,74
11
Light-colored facing brick
0,45
12
Flat, smooth concrete surface
0,54 – 0,65
13
Plastered surface, painted yellow – white
0,42
14
Plastered surface, painted dark
0,73
15
Plastered surface, painted white
0,40
16
Plastered surface, painted light blue
0,59
17
Plastered surface, painted gray cement color
0,47
18
Plastered surface, painted white cement color
0,32
19
Bare wood
0,59
20
Wood painted dark color
0,77
21
Wood painted light yellow
0,60
B. Roof surfaces
22
New light-colored fiber cement sheet
0,42
23
Light-colored fiber cement sheet, after 6 months of use
0,61
24
Light-colored fiber cement sheet, after 12 months of use
0,71
25
Light-colored sheet metal
0,26
26
Black sheet metal
0,86
27
Red or brown tiles
0,65 – 0,72
28
Gray cement tiles
0,65
29
New galvanized steel
0,30
30
Galvanized steel, dirty
0,90
31
Unpolished aluminum
0,52
32
Polished aluminum
0,26
C. Painted surfaces
33
Pink paint
0,52
34
Sky blue paint
0,64
35
Cobalt paint, light blue
0,58
36
Cobalt paint, purple
0,83
37
Yellow paint
0,44
38
Red paint
0,63
D. Transparent materials
39
Glass 7mm thick
0,076
40
Glass 4.5 mm thick
0,04
41
Glass with heat-absorbing surface 6.0 mm thick
0,306
42
Polyvinyl chloride film, 0.1 mm thick
0,096
43
Polyamide AFF film, 0.08 mm thick
0,164
44
Polyethylene film, 0.085 mm thick
0,109
Appendix 6. Total thermal resistance R0 of some common types of walls and roofs (For reference)
STT
Các lớp vật liệu
Chiều dày, m
Hệ số λ, W/(m.K)
R0, m2.K/W
A. Tường xây gạch đặc đất sét nung (chiều dày quy ước 110/220 mm)
1
External cement mortar layer
0,015
0,93
0,48/0,62
2
Solid fired clay brick1
0,105/0,220
0,81
3
Internal cement mortar layer
0,015
0,93
B. Tường xây gạch rỗng đất sét nung (chiều dày quy ước 110/220 mm)
(m2.K/W)