Winner of the Passivhaus Awards 2013 for Best Private House


We believe a key role is to ensure the building fabric delivers low energy performance, and we design for energy efficiency and comfort from day one. This ensures design and performance are integrated and construction costs are controlled.

From achieving the certified Passivhaus low energy standard with an award-winning B&B to a community building in a highly sensitive historic setting,

CTT Sustainable Architecture aim to bring performance and design together, perfectly.


Architects specialising in low energy design and Passivhaus

Sustainable Architecture

We use a vapour open timber frame construction system which has been optimised to remove thermal bridges and to simplify air tightness details. These houses use 90% less energy than a standard UK house. Benefits include thermal comfort, and good indoor air quality.

Education & Training

We are the authors of The Passivhaus Handbook, the first comprehensive book on Passivhaus, available from Green Books or Amazon, and also provide low energy training events across the UK and Europe.


We belong to 15-40, a collective of six London based architectural practices  sharing a commitment to radically reduce the energy consumption of buildings through a ‘fabric first’ approach.

The 15-40 name is informed by the metric that defines the maximum space heating demand (15 to 40 kWh/m².yr) used in Passivhaus and AECB building performance standards.

The members include 6 Certified Passivhaus Designers, and have extensive experience in delivering sustainable new build and retrofit projects using Passivhaus construction methodologies.  We believe that by co-operating to share ideas, knowledge and resources we are able to offer clients a greater depth of expertise.

CTT Sustainable Architecture works in partnership with Passivhaus Homes to build new low energy homes at affordable costs. We have developed a passivhaus suitable timber frame construction system and have generic house layouts that can be used for self build projects or for multiple dwellings - particularly appropriate for Land Trust or Co-Housing projects. The construction system also lends itself to a shell only service where the fit-out and external finishes can be carried out by others.


Specifications are set to PH15 (full Passivhaus) or PH30 (near Passivhaus)

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Our new housing is most often designed to the Passivhaus standard



desaturate2 Gail Leeson Photography-7570

To help new customers understand the stages involved in designing, submitting plans and building their new low energy home we have provided a typical timeline showing the key points along the route.

All the stages, from starting-out to completion, of a new build low energy house

Typical Project Timeline

Screen Shot 2014-08-13 at 15.46.46 CTT-logo The Passivhaus Handbook

Please click the Timeline above to enlarge

Photography by Gail Leeson

15-40_Logo_web Jonathan and Passivhaus Homes Van!

Here is our new Passivhaus Homes Van and Jonathan Williams exchanging contracts with the client for the Riverways Passivhaus project in Stoke Gabriel.


You can follow the clients blog here if you are interested.

Link button PH15 Kit ready to go

A PH15 Kit ready for loading and then arriving on site.


The frame components are wrapped for weather protection and packaged in pallet loads. Twelve pallets for this particular project. Delivery is by lorry with integral HIAB crane - so not too difficult to offload at the other end.

PH15 Kit Delivery