Impact of Shade on Hvac Energy Consumption in Buildings: a Residential Case Study

The impact of shade on the heating, ventilation, and air conditioning (HVAC) energy consumption in buildings is not automatically included in whole building energy simulations. Using transient system simulation (TRNSYS) software, models of the Union County Housing Authority’s energy efficient duplex enable the calculation of a monetary value for shading from trees, adjacent buildings, or shade structures such as solar panels. The value for shade was determined by calculating the difference in shaded versus unshaded energy consumption of the building for the month of July in central Pennsylvania. During the month of July, it was found that a large tree located to the south of the building could save approximately 4.7% in cooling demand and 3.3% on the electricity bill for the duplex. This value for tree shade is conservative because the detailed radiation mode in TRNSYS does not discount irradiation from shade projected on exterior surfaces other than windows. Solar panels shade the building’s roof, reducing the cooling demand by 0.57% and the electricity bill by 0.4% from the shade alone.