Net zero, Leeds

Name of project

Net zero






Project requirements

The family had originally wanted to build a newbuild Passivhaus but were unable to find a suitable plot nearby. Instead they found a Victorian detached house, which they decided to buy and undertake a ‘2050 retrofit’, enabling the family to be ‘net zero carbon’ and ‘net zero energy’. The home was refurbished over a period of four months in 2015 to near Passivhaus standards of insulation and airtightness to deliver year round comfort (thermal, acoustic and air quality). The aim was to have a warm, draught-free home with no cold surfaces and no internal condensation.

Nigel modelled the retrofit using a simplified version of PHPP (Passive House Planning Package) and the project is aiming to achieve AECB Silver with the space heating requirement of the building anticipated to be around 40 kWh/m2/year.


Triple glazed sliding sash windows supplied and fitted by Green Building Store along with PERFORMANCE entrance doors and PERFORMANCE high performance windows for certain aspects of the project (eg a fixed window behind original stained glass window as ‘secondary glazing’ and two arched windows in the attic rooms).


The sash windows have an overall heat loss (or U value) of 1.0 W/m2K, making them around 5 times as insulating as the single glazed windows they replaced.
The entrance doors have a U value of 0.9 W/m2K.

Client Feedback

Nigel Banks commented: “The windows have made a massive difference to the thermal performance of the house. Before we installed the windows, we had all the IWI and other insulation measures in place and the house was still freezing! Once the windows were installed and window reveals insulated and finished off, the house was immediately much warmer and more comfortable. A major benefit of having triple glazed windows is that they don’t get condensation on the inside and the inside pane remains warm to the touch, which also means that you don’t get draughts falling down the glass and into the room. The windows also look amazing and visitors are always commenting on them and assuming that they cost much more than they did".

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