Summary of HVAC Design Parameters for Residential Buildings

I. Heating
1. Basic Requirements
1.1 For residential buildings in severely cold and cold regions, a centralized heating system is preferably installed. Newly built residential buildings with centralized heating should be equipped with household heat metering and room temperature control devices. The heating systems for other public rooms and public spaces should be set up separately, and metering devices should be installed.
1.2 In residential buildings, in regions where the average outdoor temperature during the heating period is lower than -6.0°C, the staircase should be heated. Windproof facilities such as an air lock should be set at the entrance. In regions where the average outdoor temperature during the heating period is between -0.1°C and -6.0°C, when the staircase is not heated, thermal insulation measures should be taken for the partition wall of the staircase and the household door.
2. Heat Source
2.1 The urban heating network or industrial waste heat and exhaust heat should be preferentially selected as the heat source. When conditions permit, renewable energy sources such as solar energy and geothermal energy should be adopted.
2.2 When the heat medium parameters of the heat source are inconsistent with the required design parameters, a heat exchange station should be set up. The heat exchange station should be located as close as possible to the load center area.
2.3 Hot water should be used as the heat medium. The supply water temperature should preferably be ≤ 85°C, and when low-temperature floor radiant heating is used, it should be ≤ 60°C.
3. Centralized Heating Methods
3.1 Radiator Heating
3.1.1 Radiators that meet national or industry standards should be used. When using cast iron radiators, those with no adhered sand in the inner cavity should be selected. When using steel or aluminum radiators, anti-corrosion measures should be taken.
3.1.2 Radiators should be arranged as much as possible under the outer windows, and following the principle of preferentially arranging them in areas with a large heating load. For rooms with a large depth, radiators can be arranged on both the inner and outer sides. Radiators in the garage should be installed at a high position. When installed on the floor, anti-collision measures should be taken.
3.1.3 A thermostatic control valve should be installed on the inlet branch pipe of the radiator.
3.2 Floor Radiant Heating
3.2.1 The indoor supply water temperature should be ≤ 60°C, and the temperature difference between the supply and return water should be ≤ 10°C.
3.2.2 For rooms with a depth greater than 6m, it is advisable to divide the area with a boundary of 6m from the outer wall, calculate the heat load and arrange the pipelines separately. When arranging the heating pipes, the high-temperature section should be preferentially arranged on the outer wall side to make the indoor temperature distribution uniform. The zigzag type or parallel type arrangement methods are preferably used.
3.2.3 Near the outer wall and outer windows, the pipe spacing can be appropriately reduced, and in other areas, it can be appropriately increased. The maximum spacing should not exceed 300mm. The boundary area with dense pipe arrangement is generally within 1m from the outer wall, and the floor temperature should not exceed the limit value.
4. System Form and Division
4.1 The vertical height of the system should preferably not exceed 50m, and the pressure-bearing capacity of the radiators should not be greater than 0.8MPa. When using low-temperature hot water floor radiant heating, it should also not be greater than 0.8MPa. If it exceeds, vertical zoning is preferably set. When it must exceed, the maximum working pressure of the heat dissipation equipment and pipes should be checked, and radiators, pipes, and fittings with corresponding pressure-bearing capacities should be used for the exceeded part.
4.2 For household metering in residential buildings, a double-pipe system with lower supply and lower return of shared risers is preferably used, and an exhaust valve should be installed at the top of the riser. The load of each group of shared risers should be as close as possible. Shared risers should not be arranged in the residential building, and the inlet device of each indoor system should preferably be installed in the outdoor pipeline well. The indoor system preferably uses a horizontal double-pipe system, a horizontal single-pipe crossover radiator system, or a low-temperature floor radiant heating system.
4.3 The heating supply and return water pipes installed in the pipe well, in unheated rooms, and in places at risk of freezing should be insulated. The pipes laid in the cushion layer should preferably have insulation measures.
4.4 When a horizontal double-pipe same-way system is used indoors for household metering, a high-resistance temperature control valve should be installed on the supply pipe of each group of radiators.
4.5 Plastic pipes are preferably used for the buried heating pipes indoors. There should be no joints in the buried part. It is advisable to add an outer plastic casing or take thermal insulation measures. Exposed pipes are preferably made of hot-dip galvanized steel pipes with threaded connections. When sharing the same water system with the steel radiator system or directly connecting to the boiler, the plastic pipe should preferably have an oxygen barrier layer, or an oxygen scavenger should be added to the water system. When the buried horizontal heating pipe intersects with other pipes, the other pipes should give way and bypass.
4.6 Heating pipes should not pass through the transformer and switchgear room. When heating needs to be set in the transformer and switchgear room, panel radiators should not be used, and there should be no valves, water drainage, air release, and other devices in the room, and the pipes should be welded.
5. Heat Metering Methods
5.1 At the unit thermal inlet, a two-stage filter and a hydraulic balance valve should preferably be set on the water supply main pipe, and a filter and a total heat metering meter should be set on the return water pipe. The nominal flow rate of the heat metering meter can be selected according to 80% of the design flow rate. An ultrasonic flow meter is preferably used for the total heat metering meter.
5.2 The indoor inlet device includes a water supply lockable regulating valve, a filter, a household heat metering meter, and a return water lockable valve. The flow sensor of the heat meter should preferably be installed on the return water pipe, and the filter should be installed in front of the meter.
II. Air Conditioning
1. For villas, stacked villas, garden houses, duplex garden houses, etc., the installation position of the outdoor unit of the central air conditioner should preferably be reserved. The form of the air conditioner should be determined according to the specific situation of the project. The position of the outdoor unit of the air conditioner should consider the necessary maintenance and the space for air intake and exhaust.
2. Hourly load calculations should be carried out for each air conditioning area, and the simultaneous use coefficient should preferably be considered. The setting of fresh air should preferably be considered.
3. In principle, the condensed water and the defrosting water of the outdoor unit should be collected and discharged uniformly. The condensed water of the air conditioning system in villas, multi-story or high-rise residential buildings can be uniformly collected to the position of the outdoor unit of the air conditioner or a standpipe can be set in the pipe well of the nearby toilet for discharge.
4. When conditions permit, small central air conditioning systems such as air-cooled heat pumps and ground-source heat pumps can be considered.
III. Ventilation
1. For bathrooms without direct natural ventilation, mechanical ventilation or ventilation and exhaust facilities should be set up. When using a shaft air duct, anti-reflux measures should be taken. In heating regions, the bathroom should reserve the position and conditions for installing mechanical exhaust.
2. Mechanical supply and exhaust ventilation should be considered for the full basements of residential buildings. The fan room (excluding those used for fire protection and civil air defense) should not be located below the bedrooms or living rooms of residential buildings. Noise reduction measures should be taken at the inlet and outlet of the fan.
3. For the generator room, underground pump room, and distribution room, natural ventilation or natural air intake with mechanical exhaust should be used as much as possible. The above-ground air outlet of the exhaust shaft of the garage should be more than 10m away from the residential building, and the air outlet should not face the residential building. Its bottom elevation should be not less than 2.5m from the ground.
4. The clear height of the driveway in the underground garage of a residential building should not be lower than 2.2m, and the clear height of the parking space should not be lower than 2.0m; the clear height of the underground bicycle garage should not be lower than 2.0m. When restricted by the floor height, induced ventilation can be used in the garage.
5. For single-story parking garages with a small access frequency in ordinary residential buildings, it can be calculated according to the air change rate of not less than 4 times/h (in Shanghai, it is 6 times/h), and at the same time, the air change volume can be calculated according to a height of 3m; when parked double-decked, the exhaust air volume can be calculated according to 300m³/h per vehicle. The mechanical supply air volume should preferably be 80% - 85% of the exhaust air volume. A CO gas concentration detector should preferably be installed in the garage to control the concentration of harmful gases and interlock with the operation of the ventilation system.
6. Ventilation or air conditioning should be considered for the elevator machine room.
7. The ratio of the natural ventilation opening area to the floor area of a residential building should not be less than 5%. In addition, the position and direction of the openings should be reasonably arranged to effectively organize the air circulation.

IV. Smoke Exhaust
1. When a scissors staircase is used in a tower-type high-rise residential building and a common front room is shared, regardless of whether the scissors staircase meets the conditions for natural smoke exhaust, a mechanical pressurized air supply system should be set up separately. When the front room is also equipped with a mechanical pressurized air supply, the scissors staircase can share one air duct, and a normally open louver air supply outlet should be set on each floor.
2. (This item is applicable to the Shanghai area) For the front room or the shared front room of the staircase in residential buildings with 18 floors and below when there are qualified openable outer windows; for the staircase of the front room or the shared front room of buildings with a height of less than 100m when there are qualified openable outer windows, a smoke prevention system may not be set up; but for the dark staircase of tower-type residential buildings with more than 18 floors, a natural ventilation window with an effective area of not less than 1.5m² should be set at the top. In addition, for the staircase using natural smoke exhaust, the top floor should ensure a natural ventilation area of not less than 0.8m².
3. (This item is applicable to the Shanghai and Jiangsu areas) For high-rise residential buildings where the underground first floor is a bicycle garage, a garage, or an electromechanical room, when the staircase or the front room on the above-ground part uses natural smoke exhaust, the corresponding underground part may not require air supply.
4. When the floor area of the commercial service outlets at the bottom of a residential building exceeds 300m² or the number of floors exceeds 2 floors, it should be considered as a commercial and residential building.
5. The installation height of the pressurized air outlet should preferably be 300mm from the bottom edge to the ground. The air outlet should not be set in the part blocked by the door, nor should it be directly opposite the evacuation door of the staircase.
6. For underground garages with an area exceeding 2000m², mechanical smoke exhaust should be set up, and the system should preferably be combined with the ventilation system. Smoke prevention zones should be divided, and the area should not be greater than 2000m² (In Shanghai, the long side of the smoke prevention zone should not be greater than 60m).
7. The smoke exhaust volume of the garage should be calculated according to the air change rate of 6 times/h, and in the Shanghai area, it should not be less than 30000m³/h.
8. A maintenance space of not less than 600mm should preferably be reserved for the fan for installation and maintenance.
9. When the positive pressure air supply duct passes through an area with a potential fire risk, the duct should be a fireproof duct with a fire resistance limit of not less than 1 hour. The fire resistance limit of the smoke exhaust duct when passing through the front room or the staircase should be not less than 2 hours.
V. Gas
1. The underground pipelines in the community should preferably be laid along the road or parallel to the building, striving to be short and straight, reducing intersections, and being concentrated as much as possible. The minimum horizontal distance from the building foundation: 2.0m for medium-pressure gas pipelines and 1.5m for low-pressure gas pipelines.
2. The outdoor buried gas pipeline should ensure a minimum soil covering depth. It should be ≥1.0m under the motor vehicle lane, ≥0.8m under the non-motor vehicle lane, and ≥0.

6m under the sidewalk. If it does not meet the requirements, protective measures should be taken. Wet gas pipelines should also meet the requirement of being buried below the freezing line.
3. Gas pipelines should not be laid under the foundation of buildings or structures, nor should they pass through underground buildings.
4. The gas inlet pipe for households should preferably be introduced above the ground and be close to the gas-using point. For high-rise buildings and buildings with a designed settlement of more than 50mm, a settlement compensator must be installed on the inlet pipe. In cold regions, the outdoor exposed pipes conveying wet gas should be insulated.
5. Each household in a residential building should have one gas meter. The gas meter can be arranged in the kitchen, on the balcony, or in other outdoor public meter boxes; for villas, it is preferably arranged in an outdoor meter box. The position of the gas meter should be convenient for checking.
6. Liquefied petroleum gas pipelines, cylinders, and gas-using equipment should not be installed in the basement or semi-basement. Bottled liquefied petroleum gas should not be used in residential buildings with 10 floors or more.
7. A gas leakage alarm should preferably be installed in the kitchen of a residential building. For kitchens using artificial gas or natural gas, the probe of the alarm should be less than 300mm from the ceiling; for kitchens using liquefied petroleum gas, the probe of the alarm should be less than 300mm from the floor.