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Roundhay Passivhaus, Leeds

The Roundhay Passivhaus in Leeds is a 4 bedroom contemporary family house aiming for Passivhaus certification. The house was built using dense blockwork in a wide cavity wall construction with warm roof of timber I-beams. External finishes are a combination of timber cladding and K-render.

The project had initial architectural and Passivhaus detail design input from Eric Parks, Architect and Certified Passivhaus Designer at Buckrose Ecological Architects – up to Building Regulations and Tender submissions – with subsequent project management, procurement, building physics and detail construction input from client Richard Spencer, who is an Engineer and Certified Passivhaus Consultant at LEDA.  K & P Horton Builders were the main building contractor on the project. 21° supplied triple glazed timber windows and doors, from its ULTRA and PROGRESSION ranges, for the project, as well as designing, supplying and commissioning the MVHR system.


The project is in the process of applying for Passivhaus certification but the latest modelling for the project shows: 

  • Airtightness n50 = 0.45/h
  • Annual heating demand 14 kWh /(m2a ) calculated according to PHPP
  • Heating load 10 W/m2
  • Primary energy requirement 80 kWh /(m2a ) on heating installation, domestic hot water, household electricity and auxiliary electricity calculated according to PHPP
  • Walls: full fill cavity with 300mm mineral fibre insulation U-value = 0.102 W/(m2K)
  • Floor: U-value = 0.098 W/(m2K)
  • Roof U-value = 0.104 W/(m2K)
Triple glazed timber windows & doors

21°s ULTRA insulated frame tilt and turn and PROGRESSION tilt and turn windows were specified for the project, as well as ULTRA doors. The windows have been installed within the timber or render exterior elements, using plywood boxes with some timber noggins for additional support for the larger windows. Some of the windows were designed with splayed reveals internally to maximise daylight. 

I was familiar with 21° as I’d seen their windows and doors in situ on a number of projects. I was also keen to work with a local company. We’ve been very pleased with the windows and doors – everything’s been good. When we had a problem with a handle, 21°’s windows team quickly sent a replacement. Our builders also like them and suggested we get PERFORMANCE windows from 21° – with double glazing – for the garage and porch (outside the thermal envelope) to match the ULTRA windows and because the quality and price were good. Due to various site constraints and the use of a warm roof design, the form factor of the house was challenging, so we needed to go for the higher specification ULTRA and PROGRESSION windows to help us meet the Passivhaus requirements.

Richard Spencer

MVHR heat recovery ventilation

21° designed, supplied and commissioned the PAUL Novus 300 MVHR system, with rigid spiral wound steel ductwork for the project.

The MVHR system is working brilliantly. It is absolutely silent, even on boost, unless you stand in the cupboard with it! It was really helpful having 21° come to commission the MVHR as they spotted a small installation problem which we were then able to rectify.

Richard Spencer

More information

Passive House database listing


Eric Parks

Buckrose Ecological Architects

Life changing homes