Study on Heat Utilization in an Attached Sunspace in a House with a Central Heating, Ventilation, and Air Conditioning System

Abstract

Based on numerical simulations, the heating load reduction effect of an attached sunspace in winter was determined, and the effective heat utilization method and sunspace design were explored. In this paper, we studied the heating load reduction effect using heat from the sunspace and temperature fluctuation of each room at the time of heat use from the sunspace (sending air from the sunspace to the heating, ventilation, and air conditioning (HVAC) machine room and taking the air to the adjacent rooms). In the case of the all-day HVAC system, it was confirmed that a larger capacity of sunspace and not sending air from the sunspace to the adjacent room demonstrated a better heating-load reduction effect. Compared with Model Iw (a house with a window on the exterior of the sunspace opened to external air), Model I (a house with an attached sunspace on the second floor) could save approximately 41% of the total energy. Model II (a house with the attached sunspace both on the first and second floors) could save approximately 84% of the total energy. Sending heat from the sunspace to the adjacent room led to temperature increases in the adjacent rooms. However, if the construction plan is to have the sunspace only on the second floor, the house should be carefully designed, for example, by placing a living room on the second floor.

Thermal and Optical Properties of the Sunspace Casing as Factors Influencing Temperature Rise in Greenhouse Systems

“…Nevertheless, in such facilities, a significant temperature increase in the greenhouse was also observed by Rempel et al [ 11 ]. During research conducted in Japan by Ma et al, temperatures of up to 40 °C were recorded on sunny winter days inside the glazed loggia, and the period in which temperature exceeded 30 °C accounted for over 70% of the measurement time from November to February [ 12 , 13 ]. Experimental studies on historic small buildings in Spain also confirmed the effectiveness of greenhouses in passive heating of the air.…”

“…A different approach, also giving good results as to the energy savings, was using the buffer effect of the solar space, without air exchange with the living zone. This strategy allowed higher internal temperatures to be obtained within the sunspace, and some researchers reported this solution to be more effective than an intensive air extraction [ 13 ].…”

Optimal Vent Design for Additional Sunspace of Passive Houses in Rural Areas

“…But the application effect is not as ideal as expected, because the construction process is not standardized. In fact, the heat exchange between the sunspace and the house mainly exists in the form of convection [20]. The most effective way to promote the convection is to build vents on the inner wall, which can be controlled manually based on the temperature in the sunspace.…”