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The greenest building is the one that already exists

As a practice we specialise in the adaption and re-use of existing and historic buildings, to help make them as sustainable as possible. Our two directors are passionate about sustainability and the historic built environment. With Stuart having expertise in all things eco-tech and Kirsty a qualified Conservation Architect, they make a great combination.

We were heartened by the campaign launched recently by the Architects Journal encouraging the Re-use of existing buildings. RetrofitFirst asks architects to sign up to putting the re-use of buildings first and to work , where possible, with what is already in our built world. The quote above is from last week’s magazine cover and we thought it perfectly encapsulated our own beliefs about working with existing buildings in the south west.

Staddons Cottage was insulated at ceiling level using sheep’s wool between the joists and lime plaster on a new lath structure.

The demolition of existing structures to enable the building of new ones is clearly not a sustainable approach – even if the new building uses less energy. The best approach is to help make our existing building stock more sustainable by reducing unnecessary air leakage, improving insulation in an appropriate manner and making sure they are well looked after by carefully repairing and renewing them.

Old buildings are incredibly adaptable – not something that can always be said of our new building stock, which is often difficult to adapt to new uses. Careful extensions and alterations to older buildings can help to breathe new life into a project, without detrimentally impacting on their historic significance.

Many of our projects use natural, breathable insulation to help reduce heat loss. The use of natural fibre insulation is growing rapidly at the moment, with natural and sustainable options on the market such as sheep wool, find out more here. This is particularly successful when converting loft spaces or barns. Solid walls however don’t always need an additional layer of insulation, with thick stone and cob walls working as excellent heat stores. The image below shows the addition of external wood fibre insulation to a 1970’s extension. This approach works well with existing cavity walls, although insulating internally is often a better approach for listed buildings.

The image above shows wood fibre insulation being added to an existing 1970’s extension, which was rendered with breathable lime. This was part of an overall refurbishment project and included replacing windows and doors to create a a much more airtight construction, Heating was replaced with a wood pellet boiler utilising the RHI.

Historic England encourage owners to look to the past for solutions to problems of heat loss and draughts. Historically home owners would have hung tapestries and had thick curtains or shutters to help keep them warm. A similar approach today and help keep your Listed property warm without unnecessary intervention. See their advice on their website here.

Repairing old windows is also a much more sustainable approach than replacing them with UPVC. Many windows are able to be adapted with the insertion of slim double glazing units with systems like Pilkington Spacia providing a high quality option. Secondary glazing is not always the most practical solution, but can works well and companies like Mitchell & Dickinson in North Devon offer a service to repair and renovate timber windows alongside installing very low impact secondary glazing.

Using recycled materials is an approach we would like to take more often. Rotor, a Brussels-based design practice are creating a website that will help architects and building owners source recycled materials for their build. The UK version of the site can be accessed Here We are pleased to see Exeter’s Toby’s Reclamation Yard on the list, and hopefully more locations in the south west will be added. Rotor have an arm of their business that salvages materials from demolition sites and sorts them for re-use. Hopefully this idea will be will be taken on in the UK and it will become easier to source recycled materials for new build and refurbishment projects.

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Feeling the chill? How we went about insulating a heritage home

One thing about beautiful, historic houses is that they can often be really, really cold.

As Brits, we are no strangers to wacking on the fire and arming ourselves with fluffy socks and a hot water bottle, but what happens when this simply isn’t enough?

When our client came to us with a brief to create a sustainable and well-insulated home in Broadhembury, we stepped up to the challenge.

They were concerned that it wouldn’t be possible to insulate the existing solid cob and stone walls, which were a large part of the property’s character and charm.

The property wasn’t listed so there was a bit of flexibility on altering the existing fabric, and with our experience of improving the energy performance of existing buildings and working with listed and historic properties, we were well placed to be able to advise.

This time however we wanted to take things a step further. How could we integrate technology usually used when designing new low energy homes on a historic solid wall building?

The emphasis was on creating a living breathing house with natural materials to improve the indoor air quality and create a natural, healthy home.

We suggested bringing on board Ann-Marie Fallon, a certified Passivhaus designer, to model the existing house using PHPP software. This is a time consuming business and involves the input of a lot of data to model the way the house performs now and how it would change following adaptations such as the addition of insulation.

This enabled us to investigate how we could insulate the property and best improve on its energy performance through the type of insulation, its position (internal or external) and thickness. The software also helped us check that no condensation would occur, which is a common concern when insulating solid walls.

The existing walls were a real challenge being constructed of a mixture cob at low level and solid stone at first floor. There was a lack of existing data available for the thermal capacity of cob, and Anne-Marie had to approach the BRE to find information to create her model.  This was then used to predict how the house would behave with added insulation and calculate the potential energy savings.  Using this data we calculated the optimum thickness of insulation to give our client the best energy saving at the most economical price, without compromising the historic fabric.

Our client was also keen to use triple glazing, and we agreed that it did offer worthy benefits for this project, although came at a higher price. We decided to use triple glazing on the north facing link corridor and high performance double glazing throughout the rest of the house. Drafts in older houses are one of the biggest issues for improving energy efficiency, so replacing the windows made a significant difference to the performance of the house.

For the walls, breathable wood fibre insulation was used internally on the first floor where there was a mixture of cob and stone.  This had to be extended along the internal partition walls to prevent thermal bridging and condensation.  Part of the existing house was built in the 1970’s and had a cavity wall construction.  Here we used the wood fibre insulation externally.

The existing cement render was removed from all walls to enable them to breathe and lime render with small pieces of insulating cork used as the external finish to the older parts of the house, with a more standard lime render in other areas. Additionally, a new heating system was installed throughout powered by a wood pellet boiler and new underfloor heating laid in the new extension.

The design of the extension used an oak frame supplied by Carpenter Oak, which was wrapped in an airtight membrane and rendered in lime externally.  This gave a stunning interior space for the kitchen dining room and beautiful spaces where the ‘old meets new’ in the north facing corridor.

So if anyone tells you that an old house can’t be made warm and cosy, while retaining its historical charm and sustainable vision then send them our way!

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