Research On Thermal Design Methods And Key Parameters Of Exterior Walls Of A Residential Building Based On Heat Acclimation Demands Of Human Body

Due to the vast land and varieties of climate in China, Chinese people have formed different living habits. And this leads to different thermal comfort adaptive behavior of people in different areas. The development of heating and air conditioning technologies makes designers pay less attention to building envelop thermal performance design but depend on devices excessively to adjust the indoor thermal environment of modern buildings.In addition, as stipulated by the Code, the design indoor air temperature for building air conditioning system is constant. This causes the air conditioning and heating equipment chosen based on the design load to run at partial load at high energy consumption most of the time to achieve the intended indoor design temperature. However, the thermal comfort temperature of human body is not constant, but varies along with the change of weather. Ignoring the importance of adjustment-performance of the building envelope will cause building energy consumption to increase. Therefore, from the view of satisfying the thermal adaptation of human body, we further the studies on the method of building envelop thermal performance design aim at the goal of building energy conservation.A room in a standard floor in a residential building was selected for the research. Considering the climate characteristics of cold region and the variation characteristics of thermal adaptability of human body with the variety of climate, the thermal adaptive temperature was set to be the indoor design temperature. Heat balance equations were established for the indoor air node and the exterior wall nodes according to the principle of energy conservation, in which the indoor air was deemed as a node with heat capacity. Subjected to the outdoor air temperature as known, the solutions to the exterior wall thermal properties was obtained by solving the equations in a reversed way by Matlab programming. And the relationships among the thermal properties of the exterior wall were revealed.Firstly, we explored the relationships among the optimal thermal properties of the exterior wall without considering the bearing performance requirements on building exterior wall. Then, we also seeked the relationships among the optimal thermal properties of thermal insulation materials attached to the exterior wall taking the requirements on bearing performance of the exterior wall. And the relationship curves were illustrated for the two cases. And then, Energy Plus simulations were conducted to find out the natural indoor air temperature for buildings using traditional and new wall materials in Xi’an. Results indicate that the degree hours of natural indoor air temperature in the cooling and heating seasons can be reduced by 38.2% ~ 98.3% and 29.5% ~ 91.5%, respectively, for new material buildings comparing with the traditional material ones and the air conditioning and heating load can be reduced by 81.6% ~ 91.6% and 72.9% ~81.2% in the case without considering the bearing performance requirements; the degree hours of natural indoor air temperature in the cooling and heating seasons can be reduced by 29.9% ~ 88.3% and 42.2% ~ 94.4%, respectively, for the new insulation materials attached to exterior walls, and the air conditioning and heating load can be reduced by 77.8%~89.7% and 76.2%~85.2% respectively, in the case considering the bearing performance requirements. These tell the comfort and energy saving effects are remarkable. In addition, we also present the relationship curves of the degree hours of natural indoor air temperature in the cooling and heating seasons and exterior wall thermal properties, and the relationship curves of the air conditioning and heating load and exterior wall thermal properties, with and without considering the bearing performance requirements of building exterior wall, respectively. It is concluded that the relationship among thermal properties of exterior wall under different air conditioning and heating load reduction rates. This provides references for designers to choose exterior wall materials in accordance with the requirements on energy-saving.