Treading Lightly
With energy costs rising to new records, the focus on the performance and sustainability of our homes has never been sharper. However, there is a major area that is rarely given the attention it deserves; the amount of energy used to create the materials we build our homes with. This is known as embodied energy, and it is an important factor to consider when designing truly low-energy homes.
For example, heating a 200-square-metre low-energy home with a modern gas boiler for an entire year would emit around 50kg of carbon dioxide. This would roughly equal that embodied in 2 bags of cement, one of the most common products found on any building site. This illustration shows that we need to consider not just how homes are performing, but also what they are made from. This thought process starts at the very beginning of the project.
The first and most obvious way in which to reduce the footprint of our buildings is to adapt and work with what has been built already. In our Den project, we were able to take a 150-year-old structure that had been in the client’s family for many years and extend its lifespan for future generations to enjoy. This solution provided both a carbon saving and an economic saving to the project.
Sometimes, however, a new build is the answer to meet the client’s needs, and in these situations, there are lots of decisions that can be made to design for longevity and reduce the carbon footprint of the build.
The starting point for this is the size of the house, once again an area where economy and sustainability work hand in hand. Taking the time at the start of the project to understand how the house will function and what different scenarios need to be considered will pay dividends for the project. Clever space planning will not only save construction and running costs but will also reduce the embodied energy of your home.
Once we have considered whether we can work with an existing building and the size of any new addition, we can turn our attention to the materials we build with. Some simple rules of thumb can guide this; the first is to source materials locally where possible, the second is that natural materials are generally favourable to manufactured materials and the third is to minimize the use of high-energy materials like steel and concrete wherever possible.
Some of these principles were tested in our Pond House project where we used a deep timber frame to allow us to use a single layer of natural insulation and we replaced a concrete slab with a modular hollow concrete floor, reducing the embodied energy by over 50%. These principles continued into the interior of the house, where natural slate and oak flooring were chosen to provide a natural and tactile finish throughout.
Creating a home that has sustainability at its core is a challenging prospect with many different facets. Considering this as a factor at the outset of the project, and working closely with a design team that shares your aspirations, is key to a successful outcome.
