Technical and Cost-optimal Evaluation of Thermal Plants for Energy Retrofitting of a Residential Building

With the adoption of the recast EPBD in 2010, EU Member States faced new tough challenges, moving towards new and retrofitted nearly-zero energy buildings by 2020 and the application of a cost-optimal methodology for setting minimum requirements for both the envelope and the technical systems. Attention often is focused on building envelope technologies however nowadays technical systems can be a powerful instrumental factor in achieving high levels of energy efficiency. Thermal systems producing heating and cooling have higher investment costs but it is possible to demonstrate that in a long term they are cost effective related with traditional high efficient technologies. Refurbishment and energy retrofitting in residential buildings is frequently approached with standard and traditional technologies preventing the penetration of different but already consolidated solutions. The paper shows the technical and economical comparison between three technical systems (gas boiler, ASHP and GSHP) as option to replace an oil boiler after a whole refurbishment of an apartment residential building in Milan, Italy. The retrofitting of the envelope was standard nevertheless the most innovative choice was on thermal system.