Affordable Housing
Assisting group build projects that are ‘affordable’ is part of our core business aim. PH15 focuses on building fabric that halves space heating demand compared to other NetZero approaches. PH15 reduces the need for on-site renewable technologies and associated costs, ongoing maintenance, and replacement. Simple heating solutions using direct electricity are feasible. With rising energy prices many are trapped in fuel poverty and living in housing with poor indoor air quality. PH15 provides an affordable housing solution that addresses these problems as well as meeting our climate change commitments. PH15 can assist councils to meet their declared climate targets as we provide the carbon ‘cost’ of all our projects. Across the board PH15 provides a level of technical performance data that other approaches do not include. By working with us from an early stage of a project commissioning bodies can make significant savings on consultants.
Hook Hollow, Seend
Whitehorse Housing selected PH15 for the construction of 10 affordable homes at Seend in Wiltshire. This was the first Community Land Trust Affordable Housing Scheme in Wiltshire and was a partnership between Wilshire CLT, Seend CLT, Whitehorse Housing Association, Wiltshire Council and Homes England to provide locally needed homes. See some of the choices they made to arrive at their decision in this short film beginning with Belinda Eastland, Operations Director for Whitehorse Housing.
Why is a system approach so important?
The passivhaus approach and all the benefits that flow from it, depends on all the elements that make up the building working together. PH15 delivers this joined up methodology, with construction details that don’t need to be reworked with each new building. This saves time and money. The energy savings and comfort, the health benefits are all baked in. Sadly all too often between the design and the final
Why is a system approach so important?
implementation the critical components of the build are substituted and the relationship between the parts is lost. While new components can be checked and verified this adds costs. If this verification is omitted then some of the benefits of economy and comfort can be lost and with it a chance to make critical, long term improvements to our housing stock.
Hook Hollow CLT
Passivhaus Classic
Passivhaus and Carbon/Energy statistics:Gross internal floor area (GIA): typical 83sqm
Form Factor: 2.4 (terrace of four units)
Annual Heating Demand: 15kWh/m2
Heating load: 9W/m2
Predicted overheating: < 1%
Airtightness average: 0.2ach@50Pa (an exceptional result for a small building)
Annual PER Demand: 69kWh/sqm
PV generation of Renewable Energy: 4.5kWp array per unit.
Design: PKA Architects
Quantity Surveyors: Nixey Powell Partnership
Contractors: Winsley White Ltd
Completed: Spring 2024

Akerman Rd, London SW9
Social housing for Lambeth Council. An urban infill within a Conservation Area. Mix of lime render, brick entrance porches, brick slips and reconstituted slate roofs.
A cost-effective design due to an excellent Form Factor (1.8) of a three-storey terrace layout. A post occupancy study by UCL highlighted health benefit outcomes.
“You could hear the raspiness in her cough… she doesn’t suffer from that anymore — since we’ve been here, she doesn’t cough in the night.”
Passivhaus and Carbon/Energy Statistics:
TFA: 371sqm.
Form Factor: 1.8, with U-values of roof 0.108 W/m2K, walls 0.105 W/m2K floor 0.106 W/m2K.
Heating load: 7.9W/m2.
Predicted Heating demand: 9.1 kWh/m²a.
Airtightness test results: 0.34, 0.39 and 0.4 ach @ 50Pa.
Overheating frequency: 1.9%.
Construction by Sandwood Construction Ltd.
Completed December 2016.
PH15 Tiny House
Generic tiny house designs available.
Wide range of potential external finishes.
Highest quality fabric shell with ultra-low energy demand.
With a roof PV array the tiny house will be a net energy generator.
Affordable housing solution, minimal cost due to modest scale.
Passivhaus and Carbon/Energy Statistics:
Total energy demand 1300-1500kWh per year
Up to 18 PV panels, generating 5kWp array (5000kWh’s per year).
Heated typically by a single 500Watt radiator 500mm x 1200mm size.







