Ecohouse as a concept has been around since at least the 1970’s. There are many fantastic examples of ecohouses all round the world (some are featured in our case studies), most of them one-off designs which have focused on different eco-friendly aspects. As we transition to a sustainable economy it will be necessary to have a more comprehensive and consistent understanding of what an ecohouse is.
The short answer is that an ecohouse is designd to have a much smaller environmental footrpint during construction and use than current norms. It does this by being highly efficient in its use of energy, with renewable energy systems only where appropriate, and minimising its use of resources, to deliver a durable and flexible building that will have a long life. An ecohouse will support high quality outcomes for the health and wellbeing of its workers and residents, and deliver broader co-benefits to the natural environment and society. If an ecohouse does all these things really well it can be not just net-zero but net-positive.
That was the short answer. The long answer is much more detailed and can be hard to pin down to precise crieria. We define an ecohouse to include five key issues in its design, construction and operation.
There are three key strategies to make a house more energy efficient, all of which can be integrated into any new-build house at nil or minimal additional cost.
- Fabric First: maximising the energy efficiency of the building envelope before considering the use of mechanical or electrical systems, including Insulation, Airtightness and Thermal Breaks.
- Passive Solar: using a building’s site, climate, and materials to best manage solar gains and minimise overall energy use, including Orientation, Solar Gain, Thermal Mass and Shading.
- Natural Ventilation: using the natural forces of wind and air pressure to deliver fresh air into buildings, including stack and cross ventilation techniques and preventing overheating.
Technology dictates how a building performs for energy and water use. Often the first image people have when asked “what is a sustainable home” will be of the technology – a roof covered with solar panels – but the reasons for installing technology are not always about sustainability. The key strategies are:
- Appropriate Technology: determine the most carbon-effective approach, especially as we move towards All-Electric houses and the electricity grid decarbonises.
- Renewable Energy: on-site generation options for electricity, for heating and heat recovery systems, and energy storage.
- Water Cycle: on-site systems for reducing water use and managing rainwater.
Buildings consume a large proportion of global resources so it’s essential for an ecohouse to use resources responsibly and minimise it’s resource footprint. There are two key areas that should be considered:
- Embodied Carbon: the total amount of carbon emissions related to the making process, including all the raw materials, processing, transportation and the construction on site.
- Circular Economy: transitioning from a linear to a circular model means applying the reduce, reuse, recycle mantra to the building supply chain by reducing waste, sourcing low impact materials, and futureproofing buildings to ensure they are durable and can be adapted over time.
Assessing embodied carbon and circular economy is done as part of a building’s Life Cycle Analysis, which considers both the construction and operational impacts. Using natural building materials can be a really important way to reduce environmental impacts.
Health & Wellbeing
At the time of writing, the world is slowly emerging from the COVID lockdown, and we are all more aware of how important building design is to indoor environmental comfort, both physical and mental. The key areas include:
- Indoor Air Quality: covering the levels of pollutants, humidity, carbon monoxide and other substances.
- Comfort Factors: covering Thermal Comfort, Daylighting, and Acoustic Privacy which affect our physical and psychological comfort.
- Sense of Place: some less tangible issues such as Resilience, Defensible Territory, access to Outdoor Space and enhancing Environmental Awareness
Its important to note this relates to the workers during construction as well as the eventual residents. Some modern building materials are higly toxic and the greatest exposure occurs to the people who are handling those materials as part of their work.
This is about how the building performs beyond the immediate context of the built spaces it creates. It covers issues that are sometimes pragmatic, sometimes quite intangible, but are often the most important in terms of how the building will impact the local community and the surrounding natural environment. The key areas include:
- Regenerative Design: How design and construction methods enhance outcomes through issues such as Biophilic Design, Biodiversity, Nature Based Solutions and the potential for Net Positive outcomes.
- Local Context: How do design choices respond to locality, reflecting traditional/vernacular styles and cultural/aesthetic values, or draw on local supply chains.
- Connectivity: How do use patterns integrate with broader networks for issues such as Transport, SMART energy systems, or being Digitally enabled for home working/schooling.