NZEB and market-based renovation case study of an existing office building

The goal of decarbonizing the building stock in the EU requires a multi-fold increase of the current renovation rates. In Estonia, the non-residential building sector has had little or no public support to improve the energy efficiency. Therefore, it is essential to study the energy efficient and cost-optimal measures for non-residential building renovation to give guidance to real estate companies and other stakeholders about the renovation alternatives. Furthermore, crucial is to provide input to the government to develop the renovation grant and incentives for renovation. In this study, energy renovation measures and savings to improve the energy performance to NZEB level were identified in a large (16 990 m2 heated area) office building. For that purpose, energy use was measured, simulation model developed and calibrated, feasible and more comprehensive energy improvements and costs analysed. The improvement of lighting, AHU, heating, installation of a 69 kW PV system, and window replacement was needed to achieve the goal with a primary energy use of 163 kWh/m2. However, some of the applied measures had long payback times of 40-70 years and are not realistic to be implemented without renovation incentives.