Puzzle PiecesWorks

Performance Gap

Sometimes the building performance in use doesn’t match the design prediction.

In practice we can have 3 types of problems:

  • Energy consumption
  • CO2 emissions
  • Health and wellbeing (comfort, air quality, affordability, condensation and mould problem)

There could be huge differences between the design and the reality and the causes could be different: wrong design and presence of thermal bridges, construction problems, commissioning or occupation problems.

Talking about construction problems, how do we address the performance gap at the moment?

Clerk of works keeps an eye on the construction process and see if there are any problems, but he is not on the site all the time, so he can’t see everything.

Once the building is built is very difficult to tell if the walls are properly insulated or if there are some thermal bridges or other problems.

The UK answer

“The future home standards” is the UK answer to increase the thermal and ventilation performance in newbuild homes. It’s not the UK version of NZEB, but it’s a big improvement of the regulation.

The government proposal to address the performance gap includes 5 points:

  1. Airtightness. Now only a portion of the dwellings are airtightness tested, the aim is that all dwellings will be tested.
  2. Guidance on Build Quality will become part of the minimum standard. The guidance talks about insulation gaps, thermal bridges, airtightness, …
  3. Standardized reporting. At the moment building control bodies receive a range of different outputs to check for compliance; the proposal is to standardize the report, based on commercial buildings, and use it as a check list for the site inspection.
  4. Photographic evidence. Currently it is required for existing building, but not for newbuild dwellings. Photographic evidence will be mandatory to provide assurance that the building match the energy model.

Other bits:

  • Signed standardized compliance report and photographic evidence could be provided to the homeowner.
  • A national template with minimum requirements for a home user guide, that explain to homeowners how operate their dwelling in a more efficient way.

At this link you can fine some useful guide

During the workshop we discovered that at the moment there are similar situation in the different countries to avoid the performance gap (or not to avoid it…). There are similar inspection regime with clerk of works, but only UK is looking at the future and try to find solutions.

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