The potential for energy saving in existing solid wall dwellings through mechanical ventilation and heat recovery

Phillip Frank Gower Banfill, Sophie Ann Simpson, Mark Gillott, Jennifer White

Research output: Chapter in Book/Report/Conference proceedingConference contribution

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Mechanical ventilation with heat recovery (MVHR) is increasingly
being promoted in the UK as a means of reducing the CO2
emissions from dwellings and installers report growing activity
in the retrofit market. The behaviour of a whole-house MVHR
system installed in an experimental house, purpose built to
typical 1930s standards, has been simulated, at a series of air
permeability values corresponding to those achieved in the retrofit
upgrading process. There is a critical value below which
the air permeability, as measured in a 50 Pa pressurisation test,
must fall before MVHR makes an overall energy saving. In the
house considered this is 3–5 m3/m2.h (4–6.5 ach-1), although
more significant savings of 9-12 % are achieved when the
air tightness is improved to Passivhaus standards of 0.63 m3/
m2.h (0.6 ach-1). When the CO2 emissions are considered, the
air permeability needs to approach Passivhaus standards to
ensure an overall reduction, because the electricity needed to
run the MVHR system has a CO2 intensity almost three times
that of the gas used to heat the house. Airtightness is a critical
factor in achieving energy and CO2 reductions and it is easy for
designers to over-estimate the potential savings.
Original languageEnglish
Title of host publicationEnergy efficiency first: foundations of a low-carbon society
Subtitle of host publicationProceedings of ECEEE 2011 summer study on energy efficiency
Number of pages12
Publication statusPublished - 2011
Eventeceee 2011 Summer Study on energy efficiency - Belambra, Presqu'île de Giens, France
Duration: 6 Jun 201111 Jun 2011


Conferenceeceee 2011 Summer Study on energy efficiency
CityBelambra, Presqu'île de Giens


  • Ventilation
  • Retrofit
  • heat recovery
  • Simulation
  • dwellings
  • CO2 savings


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