Retro-commissioning (RECx) is defined as the systematic process for improving an existing building’s performance by identifying and implementing low-cost operational and maintenance improvements, helping to insure that the building’s performance meets owner expectations. RECx gathers the technical and the human approach to find and repairs shortcomings and problems of a building.

In other words, RECx involves auditing a system (both its equipment and its management) to improve its overall energy performance :

  • Insuring that equipment is in proper operating condition.
  • Reducing complaints and increasing satisfaction.
  • Reducing energy costs.
  • Increasing durability and length of life of systems.

Retro-commissioning methods will be applied on AFTER pilot sites to identify all the potential sources for energy saving and elaborate optimised scenarios to experiment ESM.

Please find enclosed a short video describing the basis of the commissioning and retro commissioning process association the inspection of the ships and buildings.This flashback reminds the origins of the concept of commissioning and presents its main characteristics:










The Retro commissioning Investigation aims at being an operational tool for the practitioners of the Social Housing Organizations’ staff.

This tool has been created during the AFTER project using the existing literature presented in the Introduction of this document.

Some adjustments have been implemented by the participating Research Institutes in order to make it as simple as possible and as precise as possible.

AFTER Energy Saving Measures cover and include a large range of interventions, systems and topics from operating management to assessment of global refurbishment.

In order to respect this intention, the AFTER Investigation Plan is a flexible that may be adapted to various types of building, equipment and measureThe structure of the existing Retro Commissioning Guides already created by American practitioners (such as the Energy Star© material already mentioned as an introduction) has been respected

in order to follow an easy and logical path for the process. For every step of the Investigation Plan, various proposals have been made in order to be adapted to all the types of Energy Saving Measures included in the process.

Complementary to the existing US literature, Research Institutes also had a very close look at the works of the French institute Agence Qualité Construction (Agency for the Quality of the Buildings) that has carried out an important work during the last two years regarding feedback on recent new buildings.

The Retro Commissioning Investigation Plan has a simple structure using grids that may be completed by the participating partners in order to obtain a final report before the implementation of optimization solutions.



For experimental purpose, the AFTER Retro Commissioning Investigation Plan has been tested in a first time on a Pilot Site in the city of Lystrup in Denmark. The objective for this testing was to evaluate the feasibility of the methodology and its application to an existing Pilot Site and an Energy Saving Measure.

The selected participant is Aarhus Kommune (Municipality of Aarhus), the second largest city in Denmark.
The partner of the AFTER project is the buildings section of Health and Care service of the Municipality, which runs approximately 4000 dwellings for elderly people.

The Retro Commissioning Investigation Plan has been implemented on the Pilot Site LYSTRUP during the first part of the year 2012 by the Aarhus Kommune staff. The Pilot Site include 14 houses for seniors from 1984 that have been going through a total
renovation to upgrade their energy level to low-energy standards in Denmark.

The AFTER Pilot Site LYSTRUP in Denmark has been refurbished in 2011. The refurbishment as included additional insulation of the roof, walls and foundations, new energy performant windows & frames with additional sun protections, additional photovoltaics panels, and ventilation system with heat recovery. The buildings are connected to district heating.

The original building was constructed in 1984 and had a quite large energy-consumption; approximately 150kWh/M2 for room heating per year; as well as low comfort, most significant problem was not being able to sustain adequate room temperature in the coldest months.
The architectural impression and the quality of the brick building were considered worthy to preserve, so it was decided to refurbish the dwellings. This gave the chance to discover/examine the cost efficiency of refurbishment/retrofitting opposed to new low energy buildings (LEB).

The objective of the retro-commissioning process (RCx) was to identify some weak points in the energy consumption of the building in order to improve its post-refurbishment performance.
The following example proposes a concrete application of the retro commissioning investigation plan as presented in the AFTER
Scientific methodology completed with the pieces of information from the LYSTRUP Pilot Site.





MILLS E. 2009 «Building Commissioning : a Golden Opportunity for Reducing Energy Cost and Greenhouse Gas Emissions.»

FRIEDMAN H. et al. 2009 «IEA Annex 47 : Cost-effective Commissioning for Existing and Low-Energy Buildings» prepared for US Department of Energy.

PECI and LBNL «Functunial Testing Guide – From the Fundamentals to the Field» prepared for the US Dept. of Energy and the California Energy Commissions’ Public Interest Energy Research program

PECI, 1999 «A Pratical Guide for Commissioning Existing buildings» prepared by Oak Ridge National Laboratory and Portland Energy Conservation, Inc.

CALIFORNIA COMMISSIONING COLLABORATIVE 2006 «California Commissioning Guide : Existing buildings» PECI, 2001 «Retrocommissioning Handbook for Facility Managers» prepared for Oregon Department of Energy.

ENERGY STAR 2005 «Building Manual. Chapter 5 : Retrocommissioning»

PORTLAND ENERGY CONSERVATION INC. 2007 «A retrocommissioning for building owners»

EFFNINGER J. FRIEDMAN H. 2010 «The Right Measures – What saves Energy in Existing Buildings»