Deep Retrofit Sample House


  • Sample house 1983 construction
  • Current BER F 387.13kWhr/m2/yr
  • Current HLI 3.46
  • BER required: B2 or better
  • HLI required: Less than 2.0 or less than 2.3 meeting the updated guidance set out by SEAI

HLI (Heat Loss Indicator) INFORMATION

  • The HLI is based on the total of the fabric and ventilation loss for the dwelling divided by the total floor area. It is calculated by the DEAP software based on a DEAP assessment accurately reflecting the dwelling at the time of the Technical Assessment. The HLI is the Total Heat Loss per m2 of dwelling floor area.
  • The HLI requirements must be met to be entitled to a Heat-Pump grant. This must be taken into consideration before work is commenced and a technical assessment carried out as part of the grant process.
  • Obtaining a HLI of less than 2.0 automatically entitles the homeowner to apply for a Heat-Pump grant
  • Obtaining a HLI of less than 2.3 but greater than 2.0 also entitles the homeowner to apply for a Heat-Pump grant making sure the following four elements are satisfied.
  • Maximum exposed wall U-value 0.37 W/m2K
  • Maximum roof U-value 0.16 W/m2K or 0.25 W/m2K where not accessible (e.g. flat roof or rafters)
  • Maximum Window U value 2.8 W/m2K* (and double glazed)
  • Maximum Adjusted Infiltration Rate of 0.5 ach

Fabric Upgrades

  • Wall Insulation
  • Roof Insulation
  • External Windows Doors (composite & triple-glazed)
  • Floor Insulation
  • Chimney & Flue Openings

Wall Insulation

  • Cavity walls constructed with EPS white board installed at the original construction stage
  • Proposed insulation upgrade: Pump cavity (40mm) bonded bead with internal drylining(62.5mm)
  • Proposed U-value 0.20W/m2k
  • BER uplift F 387.13 Whr/m2/yr =>E2 347.49 Whr/m2/yr
  • HLI improvement 3.46 => 3.07

Roof Insulation

  • Timber cut roof with 100mm fibreglass insulation between the joists
  • Proposed insulation: 200mm fibreglass layer to be installed
  • Proposed u-value 0.13W/m2k
  • BER uplift E2 347.49kWhr/m2/yr => E1 318.94kWhr/m2/yr

Window and Door Upgrade

  • Existing metal windows with 6mm air filled double glazing. U-value approx. 3.7W/m2k
  • Proposed window installation to be triple glazed with a u-value of no more than 1.1W/m2k
  • Composite front and rear doors to be installed with a u-value of less than 1.0W/m2k
  • Create airtight seal around windows during installation.
  • BER uplift E1 318.94kWhr/m2/yr => D2 271.16kWhr/m2/yr
  • HLI improvement 2.80 => 2.24

Floor Insulation Upgrade

  • There was no insulation installed at the time of construction in 1983
  • There is to be 75mm Polyiso @ 0.022W/mk fitted under the underfloor heating with a U-value achieved of 0.2W/m2k.
  • All perimeter walls, internal and external to have 40mm upstand insulation to limit thermal bridging
  • If possible, radon sump should be utilised and radon barrier installed.
  • BER uplift D2 271.16kWhr/m2/yr => D1 229.88kWhr/m2/yr
  • HLI improvement 2.24 => 1.87
  • Chimney and Flue Openings
  • There is two open fires and one range in this house
  • It is proposed that the range will be removed and one of the open fires will be blocked
  • There will be an insert stove installed to replace the remaining open fire.
  • BER uplift D1 229.88kWhr/m2/yr => C3 220.45kWhr/m2/yr
  • HLI improvement 1.87 => 1.81

Additional Fabric (HLI) Upgrades

  • We have met the HLI targets with the measures mentioned
  • The homeowner may wish to install further measures
  • MHRV (Mechanical Heat Recovery Ventilation) can be fitted
  • We would recommend that an air-tightness test be carried out to make sure that the dwelling will hold the heat generated by the Heat-Pump. The last thing a house with a Heat-Pump installation needs is a high air infiltration rate

Heating Upgrade

  • Install air to water Heat-Pump to replace 60% efficient single burner oil range
  • Space heating efficiency with a sample 6kW air to water Heat-Pump feeding into the underfloor heating: 552.73%
  • Water heating efficiency with the 6kW Heat-Pump: 321.10%
  • Heating controlled with programmable thermostats in each main room.
  • BER uplift C3 220.45kWhr/m2/yr => A2 48.25kWhr/m2/yr

Additional Grant Measure

  • Install 10 x 335W PV panels on the southeast elevation of the house
  • Electricity generated will help with the running of the Heat-Pump
  • BER uplift A2 48.25kWhr/m2/yr => A1 1.41kWhr/m2/yr


  • BER changes From F 387.13kWhr/m2/yr to A1 1.41kWhr/m2/yr
  • HLI of 3.46 improves to 1.81
  • BER with heatpump A2 and with additional PV install can get to A1

Contact us to discuss your requirements!