The Impact of Appliance Efficiency on Building Energy Performance -A Case Study for a Tianjin Eco-city in China

Buildings consume approximately 40% of the total energy use in the world. A building is a complex system whose annual energy use consists of many factors. The top five end-uses of building energy are space heating, space cooling, water heating, lighting and electrical appliances. Over fifty countries have developed efficiency standards and energy labels for residential appliances and commercial equipment to reduce energy consumption of those end-users. However, studies rarely consider the appliance efficiency in a whole building system. For this project, I used a computer-based simulation program to evaluate the impact of appliance efficiency in buildings on the heating, ventilation and air conditioning systems (HVAC). I studied the Chinese energy efficiency standards for refrigerators, washing machines, televisions, computers and rice cookers, and evaluated their impacts on two residential building prototypes being designed in an eco-city being planned and under construction in China. I found that improved efficiency of refrigerators and washing machines decreased peak load and the energy use for space cooling, but increased the energy use for space heating. The improved efficiency cut overall energy consumption and could lead to total annual energy savings of $1.2 million in Tianjin eco-city. Although several limitations exist in this project, mechanical engineers may still consider the method and results to design more appropriately sized HVAC systems. Moreover, China may consider revising its building codes in order to better manage the energy consumption in its building sector