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The Old Forge Cottage Passivhaus, Leeds

Old Forge Cottage is a newbuild 3 bedroom home located in a rural village north of Leeds, certified to the Passivhaus standard.  From the beginning, the client Stephen Cirrell wanted to build this replacement dwelling as a Passivhaus, inspired after visiting the Denby Dale and other Passivhaus projects. The client selected both a Passivhaus-experienced architect and contractor for the project (Eric Parks from Buckrose Ecological Architects and I & C Watts builders respectively).

21° supplied the triple glazed timber PERFORMANCE windows and doors and MVHR heat recovery ventilation system for the project.


With a cavity wall construction and  trussed roof – the project offers a good example of the versatility of the Passivhaus Standard. Overcoming strict planning rules did not compromise the efficiency and comfort provided by building to higher standards while keeping in local vernacular context.

The project was subject of a number of strict planning requirements, which determined the house’s traditional design. For example, the need to use of Yorkshire stone, requirement to have chimneys (even though not in use) and requirement for there to be smaller window openings, were all required by the local planning department.

One challenge for the project was to achieve Passivhaus within the limiting planning restrictions on the external appearance. Larger windows were out of the question, so the smaller areas of glazing and increased length of window frames / mullions meant lower solar gains and slightly more heat loss. This was balanced by a combination of increased levels of insulation in the roof and internally insulating the outward opening window frames.

Eric Parks - Architect

Technical data
  • Wall 0.103 W/m2K
  • Roof0.072 W/m2K
  • Floor0.123 W/m2K
  • Windows (uninstalled)0.85 W/m2K
  • Doors (uninstalled)0.89 W/m2K
  • Thermal Energy demand (≤15kWh/m2.yr)16 kWh/m2.yr
  • Thermal Energy load (≤10W/m2)9 W/m2
  • Primary Energy demand (PE ≤120kWh/m2.yr)104 kWh/m2.yr
  • Primary Energy Renewable Demand (PER)53 kWh/m2.yrn50
  • ACH@50pascals (≤0.6ach@50pascals) 0.2 ach @ 50 Pa
Renewable energy

The project location is off mains gas so an air source heat pump was chosen for the home’s minimal heating and hot water  requirements. Electricity is predominantly provided by a 5kW solar PV array in the garden, laid out on low level racking. The electricity from the panels can be diverted in four ways: in to the house, to battery storage, to the heat store or to the grid.

The system has been set up to ensure that if an appliance in the house needs power, that is supplied; if there is no call on the electricity, then it is diverted to a 13.5 kWh Tesla Powerwall 2 battery located in the garage; when the battery is fully charged, the power is diverted to the 300 litre water heat store; and when the water is heated to the maximum temperature, it is exported to the grid. This cascade system means that the maximum value from the solar power is extricated for every kWh generated. In effect, Stephen has created a personal ‘smart system’ in the house, which means that the use of renewable energy is optimised and it is effectively a fossil free home.

As a specialist in renewable energy and an active consultant in the industry, I wanted to create a high quality eco house and chose the Passivhaus standard at the start. It was also my intention that the house would have no fossil fuel power and incorporates an air source heat pump, solar PV and a Tesla Powerwall 2 battery. Whilst the renewables were an element that I wanted, it was the fabric and construction of the building that I knew would deliver the essential elements of the project and the Passivhaus standard did not disappoint. Now that the house is complete, I am experiencing the benefits of living in a well-designed and extremely well built home, with a minimal impact on the environment. The incorporation of renewable energy takes the house to another level, aiming for the outcome of being a ‘no bills’ house. The operation of the smart system will be monitored over the next twelve months to see how this system is developing.

Stephen Cirell - Client

Triple glazed timber windows & doors

The experience of the team meant that the doors and windows could be specified from the cost-effective, non-Passivhaus certified PERFORMANCE range from 21°.  The windows were insulated internally up to the frame.

We chose 21°’s PERFORMANCE range because I have specified it before and it had a track record of performance and affordability. It was chosen as part of ‘value engineering on the project where I was trying to find something cost-effective to counteract costs elsewhere in the project. I knew the lower specification cost-effective PERFORMANCE range would be suitable for a Passivhaus project, with careful detailing and wrapping the frames within the insulation internally. The windows also worked well with the traditional aesthetic of the project and the builders were happy working with them.

Eric Parks

MVHR Mechanical Ventilation with Heat Recovery

21° also designed, supplied and commissioned the MVHR system at Old Forge Cottage Passivhaus, alongside local M&E specialists LEDA. A Focus 200 MVHR unit with spiral wound steel ductwork was chosen.

We chose 21° for the MVHR system on the project because we had great confidence in their knowledge and expertise for low and Passivhaus energy projects. The MVHR system is functioning really well and is virtually silent in operation.

Eric Parks

Project details

Architect and Certified Passivhaus Designer

Eric Parks, Buckrose Ecological Architects,


I & C Watts; Mark Thomason, Site Foreman

M&E Design

Jim Wild CEng MCIBSE, Director & Senior Engineer at LEDA

Electrical work and security system

Steve Bowe, Guardian Alarms

Solar PV and battery storage

Electric Future Ltd, Phil Roberts Managing Director

Air Source Heat Pump

Duncan McCombie, Chief Executive, YES Energy Solutions Ltd

Landscape Design

Sally Tierney MSGD, BSc (Hons)



Case study


Life changing homes