Abstract
Cool roofs are characterized by high solar reflectance (SR) and high infrared emittance (E). When cool roofs are exposed to solar radiation, it will have a lower surface temperature compared to a similar surface with lower SR and E values, and this would result in decreasing the heat penetration into the building. Cool roofs offer significant cooling energy saving in buildings with air conditioning. In order to quantify the influence of cool roofs on the energy consumption of office buildings in Chongqing, the authors tested the electricity consumptions of air conditioners in two rooms on the top floor of an office building. One of the rooms was with cooling roof installed. The result shows that in summer, the room with cooling roof saved electricity 0.049kWh per square meter per day. However in winter, it increased electricity consumption by 0.012kWh per square meter per day.
Highlights
In China the energy consumption of the building operation accounts for 26.5% of the total energy consumption [1]
The total heat gain for a conventional dark colored roof can be as high as 366 kJm-2, the heat loss through the same roof is only about 4.2 kJm-2 [3, 4], so over the course of the day, heat gain is the predominant process for these roofs
This paper aims to determine the impact of cool roofs on energy consumption of office buildings in Chongqing, and to study the performances of cool roofs in winter and summer and an economical analysis will be carried out
Summary
In China the energy consumption of the building operation accounts for 26.5% of the total energy consumption [1]. Of many sources of electrical energy demands within buildings, the electricity used for cooling, heating and ventilation is about 66% [2]. The cooling load is influenced by the total heat gain within a building. The heat energy entering a building referred as heat gain here, can come from several sources. While heat gain is partly due to occupant body heat, electrical and gas appliances, lighting fixtures and electrical equipment, in hot climate a large portion comes from solar heat gain penetrating through the building’s exterior. While the heat gain through windows is the most severe, the energy entering a building through its walls, floors and ceilings is significant. The total heat gain for a conventional dark colored roof can be as high as 366 kJm-2, the heat loss through the same roof is only about 4.2 kJm-2 [3, 4], so over the course of the day, heat gain is the predominant process for these roofs
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