Many governments worldwide are setting more stringenttargets for reductions in energy use in government/publicbuildings. Buildings constructed more than 10 years agoaccount for a major share of energy used by the building stock.However, the funding and "know-how" (applied knowledge)available for owner-directed energy retrofit projects has notkept pace with newrequirements.With typical retrofit projects,reduction of energy use varies between 10% and 20%, whileexperience fromexecuted projects around the globe shows thatenergy-use reduction can exceed 50%, and renovated buildingscan cost-effectively achieve the passive-house standard oreven approach net zero energy status (Hermelink and Muller,2010; NBI 2014; RICS 2013; GreenBuildingAdvisor.com2013; Shonder and Nasseri 2015; Miller and Higgins 2015;Emmerich et al. 2011). Previous research conducted under theInternational Energy Agency's Energy in Buildings andCommunities Program (IEA EBC) Annex 46 identified andanalyzed more than 400 energy-efficiency measures that canbe used when buildings are retrofitted. Measures include thoserelated to the building envelope, mechanical and lightingsystems, energy generation and distribution, and internalprocesses. Implementation of some individual measures (suchas building envelope insulation, improved airtightness, andcogeneration) can significantly reduce building heating andcooling loads or minimize of energy waste, but require significantinvestments with long paybacks.However, when a limitednumber of core technologies are implemented together, orbundled, they can significantly reduce energy use for a smallerinvestment, thereby providing a faster payback.

In some countries, energy savings performance contracts(ESPC) have proven to be an effective tool for implementingenergy retrofit projects. Nevertheless, in many countries thenumber of projects funded by ESPCs still do not form a significantpart of the total investment budgeted by public institutionsfor energy retrofits. This paper presents the concept andseveral case studies that illustrate mechanisms that willincrease the acceptance of deep energy retrofit (DER) andbroaden acceptance of its implementation using ESPCs for acomprehensive refurbishment of existing buildings.