Definition of DR

The GBPN found that there was a lack of a commonly agreed definition for deep renovation, additionally, there are a variety of terminologies in use by different regions. The definitions most commonly found globally are: deep renovation, deep retrofit and deep refurbishment.

The largest differences in definition occurred in the EU and the US.  The GBPN found that confusions arising in defining a deep renovation hinder the uptake and demand for these deep energy improvements. Therefore, GBPN’s goal was to establish a clear and harmonised definition for deep renovation.

We convened collaborators on both sides of the Atlantic and around the world in order to formulate coherent definitions.  To coordinate this, we set up webinars and surveys to bring our international building energy efficiency experts together and to gain the benefits of their insight.

Together we reached a general understanding on the most commonly used expressions: deep renovation and deep retrofit. The Deep Renovation Definitions Report presents the results and outcomes of the collaborative research.

Deep renovation is the term most commonly used in Europe and focuses on heating, cooling, ventilation and hot water and the general understanding is that these should lead to a reduction of at least 75% compared with the pre-renovation levels.

Deep retrofit is the term most commonly used in the US and calls for reductions in the range of 30% to 50% compared with the pre-retrofit levels. This is based on full energy consumption including plug load. 

This Lab will be used as an area to discuss any other issues around a deep renovation definition.  We would like to discuss other subjects that are relevant and that provoke debate, for example, what should absolute targets for both deep renovation and deep retrofit be?  The GBPN found that factors could be used when defining deep renovations, for example a factor four or factor 4 renovation is deep renovation with energy consumption reductions of 75% compared to pre-renovation performance (see other factors in the definitions report).

This is a unique attempt made by the GBPN to set up a forum on “Deep Renovation Definitions”. We encourage anyone who is interested in deep renovations to become involved in our discussions and provide us with feedback on the results presented in the Report. We look forward to and welcome your participation.

All material on this page will be used to strengthen the GBPN research project on more and deeper renovation.

Contribute your ideas by using the forum of discussion below!

Sophie Shnapp, GBPN Policy Analyst is responsible for moderating this Laboratory.
If you have any questions or queries relating to this Lab, contact her!


Deep Renovation or Deep Energy Renovation is a term for a building renovation that captures the full economic energy efficiency potential of improvements. This typically includes a focus on the building shell of existing buildings in order to achieve very high-energy performance. The renovated building consumes 75% less primary energy compared to the status of the existing building before the renovation. The energy consumption after renovation for heating, cooling, ventilation, hot water and lighting, is less than 60 kWh/m2/yr. (Definition often used in Europe) [Source: GBPN, 2012]

Deep retrofit or Deep Energy Retrofit implies replacing existing systems in a building with similar ones that are of higher quality and performance, which leads to a better energy performance of an existing building. The primary energy consumption includes energy used for heating, cooling, ventilation, hot water, lighting, installed equipment and appliances. After the deep retrofit the buildings consume 50% less primary energy compared to the status of theexisting building/s the retrofit (Definition mainly used in US). [Source: GBPN, 2012]