Thermodynamic investigation of building integrated energy efficiency for building retrofit

A thermodynamic calculation model, building envelope exergy cost of unit construction area, which combines the economic and energy efficiency of building envelope and cooling and heating resource, is proposed in the paper to evaluate the building integrated energy efficiency. The model is found on “counterbalance of load” and the building life cycle is also considered. The model is applied to analyze typical building envelopes of the case to decide which one is the best. An office building with 3 building envelope energy efficiency retrofit schemes is applied as the case. The building envelope exergy cost of unit construction area, energy consumption, exergy consumption and CO2 emission of the 4 cases are all analyzed to determine the performance of the retrofit schemes. The results show that the building envelope with good insulation can help to reduce energy demand for cooling and heating. The building envelope energy efficiency retrofit schemes would reduce the building's energy consumption and CO2 emission but it would increase its exergy consumption during its life-cycle. Taking energy efficiency, exergy efficiency, building envelope exergy cost of unit construction area and CO2 emission into consideration, an optimization algorithm for the building envelope energy efficiency retrofit is brought forward.