There is no one single definition as to what constitutes an ‘eco house’. What’s more, there are several interchangeable terms used to describe an eco home — from ‘ecologically sensitive’ to ‘sustainable’ (which typically means using materials from well-managed sources) to ‘green’ and ‘environmentally friendly’.
In basic terms, an eco house, by design and construction, minimises its environmental impact. This could mean the house is designed to use minimal energy and/or replaces the ecology lost when the house is built through, for instance, including a green roof.
Here, we set out the key elements to creating an eco-friendly home.
Designing an Eco Home
When designing an eco home, it’s worth deciding what you want to achieve: reduced energy bills, a healthier internal environment or a more sustainable way of living, perhaps?
There are a number of approaches to eco house design including:
- Fabric first (for example, Passivhaus)
- Carbon neutral
- Cradle-to-cradle (which looks at the lifecycle of materials)
- Healthy homes
- Biophilic (linking the house to nature)
- Holistic design (which looks at the impact of the house on the people living in it and the local environment)
- Earthship Biotecture (building entirely with natural and recycled materials).
Sometimes these approaches are mixed to create an eco home.
Key Elements of an Eco Home
An eco house could include some or all of the following:
- High levels of insulation
- High levels of airtightness
- Good levels of daylight
- Superior double or triple-glazed windows
- Passive solar orientation — glazing oriented south for light and heat, and minimum north-facing glazing to reduce heat loss
- Thermal mass to absorb that solar heat
- Brise soleil, deep overhangs, air conditioning and other features to manage overheating
- Heating and/or hot water provision from a renewable source (such as solar, heat pump or biomass)
- A healthy indoor environment, which may include a mechanical ventilation with heat recovery (MVHR) system in a highly airtight home
- Specifying electricity from a ‘green’ supplier
- Renewable energy systems, such as solar PV and solar thermal
- Natural materials and an avoidance of plastics
- Rainwater harvesting and greywater collection
- Living off-mains.
Treat this list as a menu rather than a shopping list, picking elements best suited to your project, the site and the occupants.
Want to build your own? Take inspiration from 20 of our favourite eco homes
Here, we’ll explore some of these areas in more detail:
Energy efficiency (and the associated low running costs) is often high on the list when we think of eco homes. Often first thoughts turn to space heating. But an eco house needs to address energy consumption wherever it occurs: hot water and electricity consumption (with LED lighting throughout the house, for instance) is also important.
When it comes to building an eco home, the materials used are key — and this can be quite a complex area to unravel. The materials that go into building an eco home may include one, some, or all of these:
- Sustainably sourced materials. Whether’s it’s Forestry Stewardship Council (FSC) certified timber, which is stocked as standard in most builders’ and timber merchants, or recycled plastic products, a knowledge of where materials are sourced is often key.
- Materials with a low carbon footprint: The carbon dioxide produced in the manufacture and transportation of a building material or materials can affect how green a home is. (Strathclyde University published a paper in 2013 showing that the embodied energy in a house can be equivalent to up a quarter of the total lifetime energy demands of the house.)
- Natural materials such as straw bale, lime, or sheep’s wool and cellulose insulation.
- Recycled materials: For those seeking to build an eco home, reused and recycled are also important.
Using Sustainable Materials as Part of an Eco Self Build
Neil and Mary Gourlay’s eco house in Scotland draws on the four Rs of sustainability: reduce, reuse, recycle and recover.
It incorporates reclaimed railway sleepers (sawn, treated and polished by local craftspeople), used to create the timber flooring and functional furniture.
A Kachelöfen biomass stove heats up the dry-stone wall that runs through the house and provides thermal mass. (The dry-stone wall is made from stones stacked in the corners in a neighbouring field.)
The homeowners, a retired farming couple, have also used local sheep fleece to insulate the property — 150mm of sheep’s wool insulation sits behind every wall.
A purist eco builder will attempt to replace the ecology that the house stands on. A green roof will usually not support the same plant and animal life that the ground did and will not usually be maintained in the same way that a garden is. It therefore needs specialist planting, which in turn is likely to attract different insects and other animal life.
A green wall is similar to a green roof, but vertical and with different plants and is, perhaps, an even clearer statement of eco credentials. They are normally not installed to all the walls of the house, maybe just one wall or even a part of a wall. Even so, they will have a dramatic effect on the fauna using the garden.
Passivhaus is probably the best known fabric first standard, where the envelope of the house is designed to minimise the heat loss of the house, and consequently its energy demands.
It deals with insulation, airtightness, thermal bridging, and so on, as well as thermal mass, glazing and orientation. Fabric first considers how the house can be used to heat itself — using the fabric of the house as part of the heating system. If reducing running costs is the only criterion, then fabric first is the way to go.
Another standard, called the Active House, takes a broader approach. It looks at thermal efficiency, as Passivhaus does, but also considers sustainable materials, CO2 emissions, water consumption, resource depletion and the impact on the local ecology.
To comply with this standard, you need to generate at least as much energy as the house consumes and consider the health and comfort of the occupants.
To an extent, this is instead of or in addition to the fabric first approach. The builder either achieves an energy-efficient envelope or provides low-cost, low-carbon energy from renewable sources. The two are not mutually exclusive and an energy-efficient house needs less investment in renewable energy.
Read our complete guide to renewable energy here.
How to Build an Eco Home on a Budget
If you’re building from scratch, designing a slightly smaller house and/or one with simple shape (think rectangular) will help reduce build costs to begin with.
Other cheaper and more effective things to do for new and old homes include:
- Glazing: Often the starting point in a refurbishment or renovation project is to replace single-glazed windows with double glazed, and this will have a big impact. Secondary double glazing will cost much less and have almost the same impact on energy consumption.
- Airtightness or draught-proofing. For energy efficiency, it offers the best £ for £ return, and in older houses is likely to have the biggest impact on reducing energy consumption. This is likely to cost £300 or less.
- Solar panels: In eco terms, installing solar panels for hot water is the first and least that can be done.
- Insulation: Thermal efficiency is a core element of any eco home and insulation is a key component of that. Focus on getting the insulation as consistent as possible on the whole envelope.
- Recycled materials: The local salvage yard is likely to be a repository of useful (and cheap) materials. Try to break the cycle of buying everything new.
- Green the plot: Where you can, get rid of hard surfaces such as tarmac, brick drives and concrete. Grass is of little interest to insects, and adds nothing to the ecology. A mixed species, grassed area (with plantain, daisy, chamomile, yellow rattle, maybe some wild flowers) is more interesting to look at and useful to the fauna in the area.
- LED lighting: LED light bulbs are now affordable and have a big impact on electricity consumption.
All projects have a budget and that implies compromise. An eco house is no different.
An Eco Conversion Completed for Just £35k!
Clare Williamson and Oscar Baldry converted a former newsagents in Shropshire into a unique home, adding a timber frame first floor extension above to provide further accommodation.
Clare, a Passivhaus-certified designer, used this conversion and extension project to try out some key Passivhaus principles. The property has been thoroughly insulated and made airtight. It also features a mechanical ventilation with heat recovery system.
The couple took on most of the work themselves, achieving an impressive build cost of just £35,000.
A Final Note on Building an Eco Home
Any move towards eco building is a good move. There is no right and wrong approach, only good or better. The budget may dictate that popping a solar thermal panel on the roof is all that can be done, but this can make the house more eco than the one next door.
The Association for Environment Conscious Building provides good advice and guidance to the eco builder.
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