Energy Efficient Barn Conversion, Yorkshire

‘Box within a box’ designed using Passivhaus principles

Pete Smith has undertaken a selfbuild retrofit of an agricultural building, creating a well-insulated home within the barn. The project is effectively a ‘box within a box’ constructed within the original barn building.  It was designed using Passivhaus Planning Package  (PHPP), provided by Phil Bixby of Constructive Individuals, and has achieved an airtightness of 0.40 ach @ 50 Pa.

21°’s PERFORMANCE range of triple glazed timber windows and doors, MVHR ventilation system and airtightness products were specified for the project.

Design

Pete Smith decided to undertake an energy efficient conversion of a 14 year old portal steel-framed agricultural building, with most of the work undertaken by himself and two novice helpers. The design aimed to fit in with the agricultural industrial aesthetic, with form following function. The outer barn wall was protected with board on board rainscreen cladding. The inner box was made of:

• 18mm structural ply
• 220mm timber studwork
• Rockwool insulation
• Kingspan

Ventilation void

There is a 50mm void around the inner box of the building with numerous ventilation channels to prevent moisture build up on the inner structure. There are also 70mm holes in the structural ply to allow for transmission of moisture-laden air.

Materials

In an attempt to reduce the embedded energy cost of materials and lock up carbon in the structure, Pete sourced a wide variety of recycled materials including: 7000 handmade bricks from a church and prison; a steel portal frame from a scrap yard; 90 square metres of used scaffolding boards for the first floor boarding; 100 tons of crushed brick nuggets.; 6 tons of dutch elm affected timber; 100 metres of redwood timber from a demolished railway bridge.

Triple glazed timber windows & doors

Green Building Store’s PERFORMANCE triple glazed timber inward-opening windows, entrance doors and tilt and slide doors were chosen for the project and were finished in RAL 9001 inside and out.

The windows were carefully positioned in the middle of the insulation – which means they are set back somewhat – with splayed reveals to allow more daylight into the building. The external window frame has a width of 103mm but most of this is covered with insulation so the windows appear virtually ‘frameless’.

A large double height window and door was designed for the south elevation and comprised of a 2 metre high tilt & slide door and a 2.5 metre fixed window above it, creating the effect of a 4.5 metre glazed area.

Pro Clima airtightness products

The project utilised a number of Pro Clima airtightness products, including Intello Plus, Tescon VANA, Tescon PROFIL, Orcon F , Tescon Primer, Kaflex and Roflex grommets and Contega Fiden Exo expansion tape, supplied by Green Building Store.

Heating

The home is designed to be all electric with the  heating for the home is provided by an air source heat pump, supplemented by an airtight woodburning stove.

MVHR mechanical ventilation with heat recovery

21° designed, supplied and commissioned the MVHR system for the project. A PAUL Novus 300 MVHR unit with an electric post heater (supply air duct heater) was specified to help meet the heating demand of the project. Pete Smith installed the system himself including insulating the ductwork pipes.

Conclusion