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2.2 Thermal Design Zoning for Buildings in China
Compared with public buildings, the internal heating power and building volume of residential buildings are relatively low, so the thermal performance of residential building is more dependent on the external meteorological environment. Compared with the regions at the same latitude all over the world, China is partial to hot in summer and cold in winter. Many regions in China need the heating in winter and cooling in summer, so the energy consumption problem is more serious.
China is within the middle and low latitudes of the northern hemisphere, the land area stretches between the latitudes of 18◦N and 53◦N. The maximum solar altitudes vary a great deal, and there is a large diversity in climates, especially for the temperature distributions during winter. Different climatic conditions also have different requirements on the design of residential buildings.
Figure 2-1 Building thermal design division (GB50176-93)
In order to make the civil building thermal design adapt to the regional climate, implement energy conservation and environmental protection policies, improve the residential building thermal environment and raise the heating and cooling energy efficiency, China adopted corresponding thermal design specification requirements《Code for thermal design of civil buildings-GB50176》(1). According to this code, China was divided into five different climatic zones from north to south, which are Severe Cold (SC) Zone, Cold (C) Zone, Hot Summer and Cold Winter (HSCW) Zone, Hot Summer and Warm Winter (HSWW) Zone and Temperate (T) Zone, respectively. One of the most important characteristics of the Chinese climate is that
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winter and summer have long durations. Climate- responsive building strategies that are appropriate for each zone need to be implemented.
Building thermal zoning standards and design requirements have been showed in Table 2-1.
The average temperature of the coldest month and the hottest month are taken as the key indicator of subzone, the number of days of Daily Mean Temperature (DMT) ≤5ºC and ≥25ºC are taken as an auxiliary criterion. Different climatic zones have different design requirements of heat preservation in winter and heat protection in summer.
Table 2-1 Building thermal zoning standards and design requirements
Zone Name
Zoning Standard
Design requirements
Main Auxiliary
Severe Cold Average temperature of the coldest month is ≤-10ºC
The number of days of DMT ≤5ºC is ≥145
Must fully meet the requirements of heat preservation in winter;
Generally do not consider the heat protection in summer
Cold
Average temperature of the coldest month is
0~-10ºC
The number of days of DMT≤5ºC is 90~145
Meet the requirements of heat preservation in winter;
Consider the heat protection in summer in some areas
Hot Summer and Cold Winter
Average temperature of the coldest month is
0~-10ºC
Average temperature of the hottest month is
25~30ºC
The number of days of DMT≤5ºC is 0~90;
The number of days of DMT≥25ºC is 40~100
Must meet the requirements of heat protection in summer;
Consider the heat preservation in winter
Hot Summer and Warm Winter
Average temperature of the coldest month is
>10ºC
Average temperature of the hottest month is
25~29ºC
The number of days of DMT≥25ºC is 100~200;
Must fully meet the requirements of heat protection in summer;
Generally do not consider the heat preservation in winter
Temperate
Average temperature of the coldest month is
0~-13ºC
Average temperature of the hottest month is
18~25ºC
The number of days of DMT≤5ºC is 0~90;
Consider heat preservation in winter in some areas;
Generally do not consider the heat protection in summer
2.2.2 Climate characteristics and requirements for architectural design
In order to distinguish the influence otherness of climate conditions in different zones of China on the building, clarity the basic elements of building in each climate zone, and provide the climate parameters of building, China formulated the 《Standard of climatic regionalization
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for architecture- GB50178-93》in 1993(2), this standard described the climate characteristics of each zone and basic requirements of building located in each climate zone.
1. Climate characteristics of each zone
(A) The Severe Cold Zone: very long and Severe Cold in winter, short and cool in summer, the average temperature in January is -31ºC ~-10ºC, the average temperature in July is below 25ºC, the annual range of outdoor air temperature is larger. The west is dry and the east is moist. The annual average relative humidity is 50%~70%, the annual precipitation is 200~800mm. The freeze-up period is long and the accumulated snow is thick.
(B) The Cold Zone: long, cold and dry in winter, hot and humid in summer, the precipitation is relatively concentrated. The average temperature in January is -10ºC ~0ºC, the average temperature in July is 18~28ºC. The annual average relative humidity is 50%~70%, the annual precipitation is 300~1000mm. Spring and autumn are short and dramatic changes in temperature.
The sunshine is relatively abundant.
(C) The Hot Summer and Cold Winter Zone: sultry in summer, humid cold and small daily range of temperature in winter, the annual precipitation is large, the sunshine amount is less.
The average temperature in January is 0ºC ~10ºC, the average temperature in July is 25ºC
~30ºC. The annual average relative humidity is 70%~80%, the annual precipitation is 1000~1800mm. It is the Meiyu Period in late spring and early summer, the overcast and rainy weather is much, there are frequently heavy rains and rainstorm.
(D) The Hot Summer and Warm Winter Zone: hot in summer, warm in winter and a high humidity all the year round. Both the annual range and daily range of outdoor air temperature are small, the annual precipitation is large. The average temperature in January is higher than 10ºC, the average temperature in July is 25ºC ~32ºC. The annual average relative humidity is over 80%, the annual precipitation is 1500~2000mm. There is frequently stormy weather because coastal areas suffered from many tropical storms and typhoons. The solar radiation is strong, the sunshine is abundant.
(E) The Temperate Zone: mild in winter, cool in summer, clear dry and wet seasons. The average temperature in January is 0ºC ~13ºC, the average temperature in July is 18ºC ~ 25ºC.
The annual average relative humidity is 60%~80%, the annual precipitation is 600~2000mm.
Foggy all around the year, the annual range of temperature is less, the daily range of temperature is larger, the sunshine is less.
2. The basic requirements of building in each climatic zone
(A) The Severe Cold Zone: The building located in the Severe Cold Zone must be fully meet the requirements of cold protection, heat preservation and freeze prevention in winter. It does not need to take into account the thermal protection in summer. The general plan, the monomer
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design and structural treatment should make the buildings meet the requirements of the sunshine and cold wind protection in winter. Buildings should take some energy-saving measures such as the reduction of exposed area, the improvement of the airtightness in winter, and the reasonable utilization of solar energy. The accumulated snow and freeze-thaw erosion and harm should be taken into consideration in roof construction.
(B) The Cold Zone: The buildings located in this zone must be meet the requirements of cold protection, heat preservation and freeze prevention in winter. The thermal protection of partial area should be taken into account in summer. The general plan, the monomer design and structural treatment should make the buildings meet the requirements of the sunshine and cold wind protection in winter. The main rooms should avoid the sunshine from the west. Buildings should take some energy-saving measures such as the reduction of exposed area, the improvement of the airtightness in winter and ventilation in summer, and the reasonable utilization of solar energy.
(C) The Hot Summer and Cold Winter Zone: The buildings located in this zone must meet the requirements of thermal protection in summer, ventilation and cooling, and appropriate cold protection in winter. The general plan, the monomer design and structural treatment should be conducive to good natural ventilation; the buildings should avoid the sunshine from the west, and meet the requirements of moisture-proof, rain-proof and flood control.
(D) The Hot Summer and Warm Winter Zone:
The buildings located in this zone must meet the requirements of thermal protection, ventilation and rain-proof in summer. The cold protection and heat preservation in winter need not be considered. The general plan, the monomer design and structural treatment should be clear and bright, full utilization of natural ventilation, the buildings should avoid the sunshine from the west and set the sunshade, and it should meet the requirements of moisture-proof, heavy rain-proof and flood control.
(E) The Temperate Zone: The buildings of partial area located in this zone must meet the requirements of cold protection and heat preservation in winter. The buildings should meet the requirements of rain-proof and ventilation in wet season, need not take the thermal protection into consideration. The general plan, the monomer design and structural treatment should be conducive to good natural ventilation in wet season. The main rooms should have good orientation; the buildings should pay attention to moisture-proof.
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