Infiltration

The infiltration rate for any given building is primarily a function of construction standards and the wind speed outside of the building. Without reductions in infiltration, the effect of the other specifications is not as significant. Placing taller buildings on the winter upwind side of the project could reduce the infiltration rate by reducing the local wind speed around adjacent buildings.

200 250 200 150

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200 250 200 150

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□ Low quality construction, low insulation

□ High quality construction, high insulation

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Cooling Energy

Figure 4 Comparison of yearly heating and cooling energy for high quality construction and high insulation versus low quality construction and low insulation for multi-family residential buildings in Beijing

Heating Energy

Cooling Energy

Figure 4 Comparison of yearly heating and cooling energy for high quality construction and high insulation versus low quality construction and low insulation for multi-family residential buildings in Beijing

Figure 6 Heating energy versus winter infiltration rates. Increasing the interior insulation for a 200 mm concrete wall has a substantial improvement over an uninsulated wall. Thicker levels of insulation have a progressively smaller influence.

Heating Season ACH

Figure 6 Heating energy versus winter infiltration rates. Increasing the interior insulation for a 200 mm concrete wall has a substantial improvement over an uninsulated wall. Thicker levels of insulation have a progressively smaller influence.

Figure 5 Heating energy for different levels of airtightness with levels of foam insulation

Figure 7 Heating per unit floor area versus thickness of foam insulation for medium- and high-quality construction

All of the buildings should have modest window area and the best quality construction for the windward side of the building. Figure 8 shows that reducing the outdoor airspeed by 50 percent could reduce the infiltration rate by about 50 percent or more. In addition to airspeed, infiltration can be reduced by means of following careful construction practices used to create an airtight building, in particular around openings such as doors, windows and vents.

Throughout most of the summer, the reverse is true; increased ventilation reduces the indoor temperatures (Figure 9), especially at night when it is cooler outside than inside. During the warmest and most humid days, the building should be closed and mechanical cooling is required if comfortable conditions cannot be obtained by other means.

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