Construction details are how designers explain to builders exactly how a house should be built. They show the layers of materials in the walls, floors and roofs: how one piece of timber joins another; where the insulation goes; why some joints need to be sealed in a specific way. Construction details can be incredibly complex, utilising a diverse range of materials from a global supply chain.

Most houses are designed using standard details that are repeated over and over again. This allows builders to become familiar with the process and do things more quickly, and for the supply chain to ensure the required materials are always available in large quantities. This provides the economy of scale that makes mass market housebuilding so cost competitive.

The problem is, most standard details in use today do not consider sustainability, they are only intended to meet the minimum threshold for a restricted range of regulated issues, such as structural strength. Our ambition is for the ECOHUS accredited details to become the default for housebuilding.

We call them “accredited” details because our research has confirmed they will deliver high levels of performance across a range of sustainable outcomes.

Thermal

The most important thing that a sustainable house needs to do is provide good thermal insulation, to keep the inside of a house comfortable no matter how hot or cold the weather is outside. To achieve this the building envelope (the external walls, floors and roofs) must include: high levels of insulation; be airtight to stop hot air leaking through the fabric; and avoid thermal bridges where direct heat transfer can occur. This is sometimes referred to as a fabric first approach, meaning we make the building envelope as energy efficient as possible before we think about what renewable energy systems are needed.

Air + Moisture

Buildings are not inert, they interact with their environment depending on things like the temperature and humidity and how these change between the inside and outside over the course of a day. This means they need to allow air and moisture to move through the building fabric, sometimes referred to as allowing a house to “breathe”. Many modern synthetic materials are impervious to air and water. By comparison most natural materials have good breathability. Managing air and moisture movement is critical to ensure condensation doesn’t occur where it could mould and bacteria growth, or decay building fabric, and ensure good indoor air quality.

Acoustics

Making sure there is good acoustic insulation between attached houses, and between rooms within a house, is essential for creating a comfortable place to live. Building regulations in many countries includes minimum thresholds for acoustic performance because of that. During the COVID lockdown and the move to work-from-home and school-at-home, the lack of effective acoustic insulation in many of our houses and apartments became all too obvious.

Fire Resistance

Making sure people will be safe from fire in their homes is obviously critical, and building regulations include stringent criteria to ensure this. It includes the risk of fires starting within a house, or of a fire spreading between attached or adjacent building.

Embodied Carbon

Embodied carbon is all the carbon emissions related to the “making” process – the mining of raw ingredients, manufacture of building materials, transportation of these materials between factories and delivery to the building site, any waste materials that can’t be recycled, and all the energy used on the building site by plant and equipment. The important thing to know is that all of that carbon has already been released into the atmosphere when you are handed the keys to move into a new home, compared to your operational carbon emissions due to the energy you use over the years that you live there. Because we need to make a drastic reduction in global carbon emissions this decade, some argue that reducing embodied carbon is more important than operational carbon. By specifying only natural materials or other products with low embodied carbon we can ensure houses have about a third of the embodied carbon of an typical new house.

Circular Economy

The term circular economy is now commonly used, but its application to buildings can be difficult to grasp. It is about managing the full life cycle of any product so that we minimise resource use and environmental impacts at every stage of the process, and where nothing is ever discarded as “waste” but kept in a continuous loop, either reused as raw ingredients for a new product or composted back to its natural state. That’s why natural materials are such an important part of circular construction. But it also includes thinking of a full building as a “product” and designing it to have as long a lifespan as possible. This means making it easy to maintain, repair and adapt for other uses, or that it can be easily dismantled at the end of its life so individual materials can be salvaged and reused.