Optimizing photovoltaic electric generation and roof insulation in existing residential buildings

Refurbishing existing buildings to reduce energy use is a priority worldwide greenhouse gas emissions. Millions of around the globe have old roofs that are poorly insulated, but with large roof surface areas could potentially provide significant renewable generation. Often, photovoltaic panels simply added onto regardless thermal integrity. However, due weathering, frequently need repairs over their useful life. We evaluate comprehensive methodology using EnergyPlus and TRNSYS simulation tools how best combine solar electric generation improved insulation achieve cost reductions, improve efficiency utilization at time accessed. Advantages combining efforts into single intervention has not been fully explored in building research. further incorporate important impacts PV stand-off arrays on performance from shading long-wave irradiance skies. These influences comfort implications for insulated structures increasing summer heat waves associated climate-related warming. They also strong interaction installed levels. With an example analysis Milan, Italy, we considered three typical residential types wide-use world (single-family, multi-family, apartment complex) different geometries, levels constructions. evaluated two options: re-roofing (roof repair/replacement) refurbishment (energy improvement). optimized via state-of-the-art simulations considering both documented costs. was quantified detail, exploring array affects performance, influence previously considered. This particularly uninsulated where upper floors can experience excessive summertime heating. Both heating cooling needs determine optimal what savings- related costs- be obtained depending differing parameters. found appropriate cost-effective option net primary buildings. Savings alone varied 3% (apartment 17% (single-family). When adding systems initially uninsulated, savings range 55% 80% Shading reduced loads by complexes provided predicted improvements floor dwellings next exposed roofs.