Passivhaus Affiliate

Passivhaus practitioners enjoy their own handiwork

PHT members PYC are enjoying the comfort, health and wellbeing benefits of Passivhaus in their working environment - their self-built office received Passivhaus certification in April 2019. The first building to come out of PYC's new house building factory, it exemplifies their approach, and has fulfilled the multiple functions of helping them to refine their build system and construction techniques, providing a model to potential clients, and giving the team a great place to work.

PYC office


The office is a hymn to timber, from the unusual end-grain birch floor tiles to the poplar internal lining and Douglas fir weatherboarding, as well as, of course, all the structural elements under the skin. PYC is dedicated to timber throughout its operations, striving to procure wood locally wherever possible, and most of the material in their offices comes from Welsh forests.

PYC office - Green Building Store ULTRA windows and doors, birch end-grain floor

The build system consists of a single stud frame constructed using timber i-beams, a structural choice that’s economical in material, strong and thermally high-performing. The insulation, too, is tree-based, via the printed word – PYC are the UK distributors of Warmcel cellulose fibre insulation, which is made from recycled newspaper collected from offices, schools, overruns from printing companies and kerbside collections. Its sustainability credentials, including a negative Global Warming Potential of -1.5kg CO2/m² and no VOCs, are recognised by a natureplus® certificate.

PYC office - during construction


PYC were confident enough in the thermal performance of the building not to install a heating system – when the temperature drops to its lowest in the depths of winter, a single moveable 1kW electric heater is sufficient to restore comfort. In the hot summer of 2018, well-designed glazing, natural ventilation through open windows, and the stabilising thermal properties of the Warmcel insulation, kept the indoor temperature below 26° even when it soared to 31° outside.

Key facts

Energy performance

Certification date: April 2019

TFA (Treated Floor Area): 220 m²

Form factor: 3.2

Cost: £350,000

Space heating demand (≤15 kWh/m².a): 14 kWh/m².a

Primary energy demand (≤135 kWh/m².a) : 134 kWh/m².a    

Airtightness (≤0.6ACH): 0.5ACH


PYC have been instrumental in educating the Welsh government in the benefits of the Passivhaus standard, and now they have a full-scale demonstration to bolster their advocacy of the Standard. Prospective clients, whether local authorities, schools, self-builders or local business, directly experience the comfort and other advantages of a Passivhaus building when visiting the space. And the comfort, health and wellbeing of the PYC team at work is enhanced at the same time.

Deeply immersed in the building, PYC have undertaken the role of client, architect, contractor and air-tester. Help was enlisted from external suppliers including PHT member Green Building Store for the windows and doors. PHT Patron WARM provided final independent certification.

The building features in the current edition of Passive House Plus magazine (issue 32), including full construction details and embodied carbon breakdown. Passivhaus Trust / iPHA members benefit from a digital subscription to the magazine.


Further information


Passive House Plus

Green Building Store

5th January 2020

Never miss UK Passivhaus news by joining the Passivhaus Trust mailing list Follow us on twitter @PassivhausTrust

< Back To News