St Luke Street Retrofit for the Future: Retrofit Approach

A 'Whole House' Approach

A 'Whole-House' Approach to Retrofit using Passivhaus Components
Click to Enlarge

Our Retrofit of our terraced house has been designed and modeled in SAP and PHPP (Passivhaus Planning Package).

We used Passivhaus principles and components, concentrating on a 'Fabric First' approach to dramatically reduce the energy demand and CO2 emissions for this hard-to-heat terrace house in Hanley, Stoke-On-Trent.

The refurbishment works to 23 St Luke’s Street are to be to a very high energy standard, as they house and design team were successfully chosen as part of the Technology Strategy Boards ‘ Retrofit for the Future’ competition, that aims to fund retrofit projects to existing houses that are owned by Registered Social Landlords, to achieve 80% reductions in an average family home’s CO2 emissions.

The works are to be to near Passivhaus Standards, and will include:

High levels of internal wall, floor and roof insulation to existing house to achieve max. U-values of 0.15 W/mK

New triple-glazed windows to achieve a max. U-value of 0.8 w/mK

High levels of air-tightness to prevent heat loss through a leaky building

High efficiency mechanical ventilation heat recovery ventilation system to the whole house

Solar thermal panels to the rear roof to provide 60% of domestic hot water

A natural palette of materials for Insulation & Finishes

A Natural Approach

This retrofit uses insulation materials from renewable sources, such as sheepswool and woodfibre insulation, and natural mineral plasters such as lime plasters internally and clay aggregate for chimney void fills.

These materials are used for their hygroscopic/vapour-open qualities to help deal with moisture within the existing building fabric, and also reduce the embodied energy of the retrofit materials in the house, actually sequestering carbon in the build (unlike other forms of building materials, such as phenolic foamed insulation, etc,).

Energy Figures & Modelling

These measures to the house has been modeled in the energy software PHPP (Passivhaus Planning Package) to accurately calculate the reduced heating and energy demand of the house, and attention to cold bridging details have also been modeled.

We have also carried out a SAP assessment on the existing house and the proposed Retrofit works, and the above measures give the following results (although No. 23 is likely to have higher primary energy demand and CO2 emissions that average, as the house is particulary hard to heat, with no insulation, and small windows that do not face south):