What is an eco-house?

The concept of an eco-house means a dwelling that has a low impact on the environment. To see if we could deliver this, we built an eco-house in 2000, and called it The Concept House.

Performance

Buildings use up enormous amounts of energy. Some calculations make it as much as 70% of all the energy that we use in the UK when all the factors are taken into account. This energy is mainly for heating and lighting and therefore we design houses that are well insulated and make the best use of natural light. However, before even thinking about the performance of the building it is important to go back to basics; a south facing site will be a much better location than a north facing site (in the northern hemisphere) because of access to sunlight and protection from the cold northerly wind. So, an eco-house starts life in the right place, facing the sun.

Orientation

Ideally the site for the house should have a south westerly aspect and be protected from the north and east. It’s not always possible to do this but there will usually be an opportunity to take advantage of the passive solar gain by having more glazing on either the front or the back of the building. Planting trees and creating wind breaks on the north and east sides of the site can enhanced the solar gain effect by protecting the house from the cold north easterly winds.

Solar Gain

Having faced the house towards the sun we use high performance windows to draw in as much light and warmth as possible. Sunlight then floods into the house and any heat generated is retained by a highly insulated building shell, draught proof windows and doors and thermal mass within the building. (Thermal mass is dense material, like brick, stone or concrete that acts like a storage heater, taking in heat during the day and letting it out gently as the house cools down).

Active Solar

Having a sunny site also means that we can fit active solar systems, that are both solar water heating panels and electricity generating solar panels on the roofs, thus further adding to the free heat and electricity gained from the sun.

Heat Recovery

Living in the house also generates heat. Active human beings can produce as much heat as a one bar electric fire. Add to this heat from cooking, washing, lights etc. and you can begin to see how an eco-house could get too hot!

You could always open the windows of course, but we could go one stage further and design the houses so that they have heat recovery ventilation systems. These systems extract the warm, moist air from bathrooms and kitchens and take the heat out of the stale, damp air before venting it outside. The clever bit is when the heat recovery system transfers this collected heat to fresh air coming into the building and distributes it to the bedrooms and living rooms. Fresh air, at room temperature. An added benefit is that filters can be fitted on the air intake to provide a barrier to pollen or other irritants.

Liveability

With the passive and active solar gains, insulation, draft proofed building shell and heat recovery system, our houses could be zero heat, that is, in theory, you shouldn’t need to keep pumping heat into them from a central heating system.

However, life isn’t like that. Kids leave the door open, pets come in and out, people go out all day, cold snaps happen and some people like to sleep with the window open. So, the houses are designed to have heating systems that can react quickly and efficiently to any changes in room temperature as well as providing a heat boost to the water temperature down-stream of the solar panels.

And if that wasn’t enough, the primitive urge for a real fire within the home is catered for with flues for wood burners. (Father Christmas doesn’t have to negotiate the heat recovery system either).

Most importantly though, our houses are also designed to be flexible, taking into account the changing needs of a growing, and then perhaps diminishing family over the years. Load bearing internal walls are minimised to allow rearrangements of the interior spaces, and the build technology is such that local trades can carry out alterations and easy maintenance.

Health

Other benefits of an eco-house, aside from the obvious one of having minimal heating costs, are a healthy living environment. The heat recovery system eliminates dampness and the moulds that are so often a health hazard. The air intake filters prevent dust coming in with the incoming fresh air and the internal vacuum cleaner system extracts dust from the house and vents it (via the dust collection bag and filter) to the outside, thus no microscopic particles of dust remain in the house.

Natural Materials

For the health of the householder, and the planet, an eco-house should be built with materials that are free, wherever possible, from toxins or harmful products of the petro-chemical industry. However, this is only just the beginning of how we assess the eco-friendliness of the materials that we use to construct the houses.

One of the wider issues of energy efficiency is the embodied energy within the construction materials. (Embodied energy is the energy taken up with producing and transporting the materials used).

For example, we use timber wherever possible. This is because trees grow using energy from the sun, they don’t pollute, they produce oxygen, absorb CO2, they provide a wild life habitat, they can be replanted, they can be sourced locally, the timber can easily be put to some other use after a building is demolished and …. they look nicer than a cement factory.

However, cement is a very useful building material and there are places where we have to be practical and use it. However, one alternative to cement is lime. Lime has been used as a building material for thousands of years and although energy and CO2 are used in its production it gently returns back to limestone in time, taking in CO2 in the process. The Wintles houses have lime render and we try to use this instead of cement where possible. We also use reclaimed materials, particularly bricks, slates and roof tiles, to make use of the embodied energy within these materials. They also help new buildings to blend in with their surroundings.

Working from home

When designing the houses we have also catered for changing patterns of work and demographics.

Where possible the houses have extra spaces for people to work from home, and the site is wired up for broadband and other technological advances.

A small central facility providing telephone answering, meeting room, photocopier and fax is also ideal in a new neighbourhood to make working from home easier …. and more sociable.