Projects: Berins Hill, Oxfordshire

Berins Hill, Oxfordshire

Keywords: Architectural designeco buildresidential

This timber framed house was completed in 2005 for a private client in Oxfordshire. The design, being in an AONB, had to work within tight planning volume requirements and aesthetic criteria as a replacement dwelling.


We were commissioned to design a new replacement dwelling on the site of an old corrugated iron chalet in the Chilterns AONB; a previous architect’s design had been refused planning. The building was to be an accessible house for an elderly man and carer. Because of the delicate planning situation, the house needed to use a small increase in volume from the previous house, and to maintain some echoes of the old chalet seemed advantageous and desirable.

We negotiated approval for a basement to the dwelling to increase volume whilst maintaining modest appearance; a design approach adopted elsewhere on the Chilterns escarpment, where the house sits. Our clients were very keen to adopt appropriate sustainable construction methods.

The entrance level became a one bedroom living space, with bed and bathrooms accessed off a large airy open-plan living / dining / kitchen space. This prime space benefits from access to the westerly facing balcony and the view over the Oxfordshire plain.

The basement is more utilitarian with two bedrooms, bathroom and kitchenette.


A modern timber frame using structural ‘I beams’ for the walls and roof was adopted, with the basement using a masonry tanked system.
Principal features of the design;

–    timber framed; built with ‘I’ beam construction

–    full fill cellulose insulation.

–   passive solar design

–   hot water solar panels supplementing hot water heating system

“Dear Andy, Tim and Adele, I had been meaning to write to you for some time to record our thanks and appreciation for all the hard work that you, Adele and Andy put into the house at Berins Hill. The house is a triumph. It is lovely to live in, very light and really makes the most of the site. Its simple but spacious design works very well and looks stunning. It is very cosy in winter and delightfully cool in summer – perfect. We also very much enjoyed working with all of you on the project and found you to be excellent at handling and managing the build whether working effectively with the builder, smoothing the way through the planning process or indeed managing the clients! It was a pleasure to work with professionals who combined such knowledge of environmental issues, with such a practical approach to building. I hope that Adele was pleased with her handiwork when she visited the other day. I am sorry we were not there to greet her. If any of you are in the area or want to see the house please do pop in. We would delighted to see you. All the best – Richard and Kate”


This low energy house now completed in Oxfordshire was pressure tested pre-completion to determine its construction’s airtightness (air permeability) at a stage where faults could be easily rectified, Initially it achieved 3.4 m3 / m2hr @ 50 Pascals. Minor faults were rectified and internal linings completed, resulting in a final result of 2.5m3/m2hr@50Pascals. Less than 1% of houses in the UK are estimated to achieve as good a result as this.

This house is now far more likely to achieve real fuel and cost savings as opposed to theoretically predicted savings that are not actually achieved in reality.The success is due to attentive design and detailing for airtightness and the excellent build quality reached by the builder Gavin Cook of Sustainable Construction, another AECB member.

During the pressure test a smoke stick was used to find the main areas of air leakage. These were largely due to problematic details associated with the basement / adjacent suspended timber floor junction and also generally related to the basement tanking system solution used. However, a lot has been learned and the experience has shown that achieving energy efficient new build is not as difficult as many in the UK Industry appear to believe.

In addition to reducing the heat lost through uncontrolled air leakage through the structure, the use of thermally more efficient timber ‘I’ beams for walls, floor and roof will help to bring the actual U values of these elements closer to the theoretical U values by reducing the structure’s thermal bridging. It is important to remember that currently quoted UK U values can be up to 50% worse than in reality due to thermal bridging not adequately allowed for in the calculation methods, issues of problematic workmanship and other factors such as ‘windwashing’ of insulation.

Current proposed revisions to the building regulations are suggesting an air permeability target of max.10, with the AECB’s energy performance targets set at 1.5 – 3.0 for all homes built from 2010 and 0.75 for homes built after 2020.

All our portfolio projects

Garway Community Centre

Garway Community Centre The rural Herefordshire village of Garway is busy planning for a sustainable future, with construction of a new, Passivhaus certified community centre. It has taken many years’ development, but a successful bid to Big Lottery Fund in 2016 has made the project a reality. Currently three quarters through construction, the centre will provide many functions for the village, including a large multi-functional hall with full stage /...

Harold Street

A high-quality deep retrofit. Work carried out by Tom Straker, AECB member. Completed 2015. The clients are committed environmentalists, and were keen to demonstrate best practice in this modest town house.

Church Cottage

Part retrofit, part new-build extension to a small-holding cottage on the Welsh borders. Building work carried out by Mike Whitfield builders, AECB members.


Since 1998, we have been involved with projects at the Centre for Alternative Technology; working as both design consultants, and on site, as specialist rammed earth building contractors / trainers. We worked with Pat Borer, architect on the rammed earth aspects of the ATEic bookshop and offices; and then as consultants for the WISE building.

Cherry Orchard

Cherry Orchard is a Camphill residential home and farm. The building we designed is for workers and co-workers to have a generous space for their indoor gardening activities; it combines a learning centre / potting shed, with a large south-facing greenhouse. The client group were interested to use the focus of the design process, to also look at the interlinking of all the external spaces between buildings. Adele Mills led...

Huckenden Barn

Conversion of this beautiful historic Chilterns barn into a useful and dramatic, comfortable living / social space. The building work was carried out by Neil May Builders. Neil was then in the process of founding Natural Building Technologies. We had the opportunity, as conservation and ecological specialists, to trial many techniques, using natural insulants, lime mortar plinth to stonework, avoiding underpinning etc. Work was completed in 1996. The project won...


A new Passivhaus-certified detached dwelling; completed Autumn 2016. This house replaced a coach house that had been converted in the 1970’s. Our clients wanted a highly energy efficient house for its comfort value, and reduced running costs. As early adopters of energy efficiency / ecological building on other projects, they were happy to adopt the Passivhaus as an important contemporary target. The building was built by Ecovert Solutions, AECB members.


A renovation and extension project of a courtyard of derelict stone buildings; outside Aberdovey, Gwynedd. The building work was completed in 2006, and the project subsequently won an award for its quality as a tourism facility in the Snowdonia National Park. The focus of the renovation was not towards a specific energy standard; but to focus on good quality energy efficiency ( Internal Wall Insulation was required, due to need...

Berins Hill, Oxfordshire

This timber framed house was completed in 2005 for a private client in Oxfordshire. The design, being in an AONB, had to work within tight planning volume requirements and aesthetic criteria as a replacement dwelling. INITIAL CONCEPT We were commissioned to design a new replacement dwelling on the site of an old corrugated iron chalet in the Chilterns AONB; a previous architect’s design had been refused planning. The building was...

The Greenwood Centre’s Woodland College

The GWC is a nationally renowned educational charity, working to promote coppice and green wood crafts, and management of deciduous woodlands. It runs a variety of social forestry courses. We have been involved with various building projects at the GWC since 1995, when we were commissioned to design the Woodland College. This building prioritised use of local timber alongside modern energy efficient timber frame construction. In 2006 the building was extended...