Since the energy crisis of the 1970s, energy requirements pertaining to new construction and building renovation have significantly improved in many industrialized countries. The Energy Performance of Buildings Directive Recast (EPBD 2010), requires buildings to ‘be refurbished to a nearly zero-energy condition’ and states that ‘Member States shall not be required to set minimum energy performance requirements that are not cost-effective over a building’s estimated economic lifecycle.’ In the USA, the ‘Massachusetts Save Energy Retrofit Builder Guide’ refers to deep energy retrofit (DER) as the ‘retrofit of the building enclosure and other building systems in a way that results in a high performance building.’
Results from a survey conducted by project, have been used to generate a list of energy efficient technologies. The modelling process covers four different stages, including the pre-renovation baseline:
1. according to the building codes existing at the time of construction of the building,
2. according to today ́s building code levels for refurbishment of buildings,
3. according to DER targets, and
4. assuming different national targets for end- or primary energy.
In addition to the core bundle of technologies, various building type and climate specific technologies can be used in the modelling process. Some of the listed energy efficiency measures are costly and can have long payback periods when used individually. To become cost effective, DER must exploit the effects of synergy between different demand- and supply-side measures in an innovative and integrated design approach. Different non-energy-related measures such as implementation of quality assurance and quality control processes that contribute to the cost effectiveness of the DER are also being assessed.