On the Overall Energy Efficiency of a High-Performance Solar Energy Residential Building

This paper describes the energy performance of a solar house over its first year of monitoring. The 2007 Solar Decathlon house currently sits on Santa Clara University’s campus at 60.4 m². The house is powered entirely by solar PV and solar thermal off the grid. This solar energy house is heavily instrumented with more than 100 sensors to measure temperatures, humidity, power consumption of electric appliances, lighting, water, and performance of a 7.2 kW solar PV array and a sophisticated HVAC system. The instrumentation includes a full weather station. The house is divided into two interconnected modules, and constructed with high thermal insulation and sustainable materials. The instrumentation also allows quantifying energy performance of individual components as well as the overall energy performance of the house. The paper focuses on the complete energy balance of the house as a function of weather conditions, and of the performance of individual components. Of particular interest is the performance of the solar PV and solar thermal systems. The solar thermal system includes an absorption air conditioning unit, integrated with a thermal storage tank to provide all energy needs for water consumption and heating. The I-V curves of the full PV array are reported, demonstrating peak, off-peak, and seasonal performance and deviations from manufacturers’ conditions. Similarly, the overall COP of the solar-driven HVAC system is reported for both cooling and heating modes. Finally, it is shown how data can be used to demonstrate improvement of simulation tools for solar building energy performance. Although data has been collected since March 2009, this paper focuses on performance during summer 2009.