Green Building Store is now 21°

The Hen House, Sheffield

The Hen House project is an award-winning energy efficient newbuild house, built into a steeply sloping Sheffield garden site, designed by Paul Testa Architects and built by Simplicity Construction for selfbuilder clients Jo and Gail.  The house has been designed to be extremely warm and comfortable to live in whilst using very little energy compared to a typical new-build house.

21°supplied the triple glazed windows & doors and MVHR system for the project.


The house was built using Passivhaus principles, and was designed using PHPP, with a total space heating need of 36 kWh/m2 per year and a construction cost of £1975/m2

The two storey dwelling was carefully fitted into its difficult plot whilst maximising the views to the West, avoiding numerous mature trees or overlooking other  properties.

The home is accessed on the upper level, which offers a spacious, light filled kitchen, living and dining space, made from a highly insulated timber-frame superstructure provided by Frame Technologies.  The long room is divided by a full-height plywood bookshelf which maintains views through to the large balcony overhanging the slope at the far end. This upper level is clad in timber shingles which will soften with age and blend the house into its wooded surroundings. The lower floor houses the bedrooms and support spaces in a solid, masonry plinth.

We specified the PERFORMANCE range because of its excellent value for performance and also because of the quality of 21°’s customer service. Value for money is obviously an important factor when specifying. We did some cost comparisons and these windows came out really well compared to competitors. 21° is also very easy to work with and really supports us throughout the whole specification process. We have specified 21°’s PERFORMANCE range on a number of projects, including for the EnerPHit radical retrofit of my own home, which is currently on site.

Paul Testa

Triple glazed timber windows & doors

21°’s triple glazed timber windows and doors were chosen for the project. The window and door specification for the site included a large gable end with French doors and triangular fanlights, as well as long narrow windows positioned to fit in with ‘overlooking’ issues and also to take advantage of the views of wooded overgrowth

Products supplied from the PERFORMANCE range included: Tilt and turn windows, two Lift and slide doors, an entrance door and sidelights and a large triangular fixed panel. The windows and doors were finished with a clear stain inside, and opaque paint finish (RAL 7037) outside.

Thank you. We couldn’t be more impressed with the service we’ve had throughout from 21°. You’ve been absolute professionals, really easy to deal with and all-round lovely folk!

Clients Jo and Gail

MVHR mechanical ventilation with heat recovery

21° designed, supplied and commissioned the MVHR (mechanical ventilation with heat recovery) system, which included a PAUL Novus 300 MVHR unit and a rigid spiral wound steel ducting system, which was incorporated into the contemporary design of the project, rather than concealed.

It was good to work with 21° on the MVHR system for the project as a tried and trusted supplier of ventilation with heat recovery systems. The MVHR system is working really well and is virtually silent in operation, as we’d expect from 21°s MVHR design team.

Paul Testa

Project details


HEM Architects


Simplicity Construction

Frame Technologies


  • IStructE Yorkshire Region Awards 2018 – Best Small Project;

  • Sheffield Design Awards 2018 – Shortlisted;

  • Best Timber Frame House, Build It Magazine 2018 – Winner


March 2018

Case study

January 2019

Life changing homes