IEA SHC Report: Lessons learned from 20 non-residential building renovations.

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This report summarises the findings from 20 exemplary renovation projects analysed by the International Energy Agency's Solar Heating and Cooling Programme (IEA SHC) Task 47:“Sustainable Renovation of Non-Residential Buildings”. The buildings are split into three categories: educational buildings, office buildings and historic & protected buildings.


The report is divided into six chapters. It starts with an introduction on the objectives of the IEA SHC Task 47 and goes on with a summary included in chapter 2 reporting the key findings from all buildings. Chapters 3, 4 and 5 focus on the different building categories and specific projects while the last chapter lists all exemplary projects with key numbers.


Main findings before and after renovation, of the projects analysed include:




  • the smallest absolute and relative improvements in the U–values of the buildings were in the floors (due to restriction in floor height);
  • the best absolute value improvements were in the windows;
  • the walls and roof had the greatest relative change in U-value;
  • an airtightness of 0.2 h-1 (Blowerdoor test with 50 Pa over-/under pressure) had been achieved in the projects.


Technical systems:


  • photovoltaics (PV) were the most common renewable energy source installed in these buildings;
  • all buildings had an improved ventilation system;
  • limited mechanical cooling was needed, cooling demand was mostly covered by night-time ventilation or free cooling from wells designed for ground coupled heat pumps;
  • all buildings focused on better lighting systems. Some had improved the utilisation of daylight; some had installed energy efficient lights and/or installed movement sensors to save energy.




  • in all building types, large energy savings were possible through energy efficiency measures.




  • for most of the projects -with cost information available- costs for energy saving measures were in the range of 70 to 210 €/m2 with the corresponding energy savings of 45 - 60% of energy consumption.




  • most of the renovation projects had focused on other environmental qualities than energy, as improved indoor climate, environmental friendly material use and some buildings were evaluated by environmental classification systems.


Decision making process:


  • the demonstration projects showed that the typical timeframe from the initial idea of the renovation to a completed renovation is 2 - 4 years. However, there were examples showing that this period can vary significantly.


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