Foundations 

When it comes to foundations the default technology has to be concrete, which is unfortunate because concrete, and the cement it is made from,is a major contributor to atmospheric CO2. In fact the BBC's Rare Earth podcast states "It's reckoned that 8% of all humankind's carbon emissions, greenhouse gases, come from the manufacture of concrete and cement ...”   

Another interesting fact from the podcast is "that somebody added up all the stuff that humans make, and fully half of it is concrete, and that is the total amount of concrete in the world is 550 billion tons!!”

So how can we be more eco?
Well we could use less concrete but the amount we use will be determined by a structural engineer's calculations working out for the load of the house how much concrete is required - having said that, a SIP construction (see below) is significantly lighter than a traditional build (1msq of brick wall weighs 200kg where as 1msq of 200mm thick SIP panel weighs around 50kg)  and so should need less concrete.  

Another option is to use eco-concrete, a concrete which has a lower carbon footprint by using blast furnace fly ash as a substitute for cement. And by using recycled aggregate rather than freshly quarried or dredged gravel can substantially reduce the impact on the environment.  We are currently looking at whether it is feasible to use these alternatives on our build. 

Structure

Our house is made of SIPs, Structured Insulated Panels, which are a modern method of construction. The panels are manufactured in a factory and bought to site and assembled within a matter of days. 
A SIP panel is essentially made from a sandwich of insulation material between wooden boards as illustrated by this diagram.

Windows & Doors

For an eco house the main thermal insulation properties will come from the structure (walls, roof and floors) but the "holes" in the structure, the windows and doors clearly also need to have very good thermal insulation properties. 
The key for windows is the use of triple glazing and doors need to be constructed with materials which incorporate insulation. 

Power Generation & Storage

Unlike most commercially built houses, a key element of nearly all self-builds is power generation in particular photo voltaic panels and battery storage. 

Heating

A highly insulated house will need a relatively small amount of heating. 

The majority of new homes will use heat pumps, either ground source or air source, for heating both air and water. 

However, in our case the insulation, air tightness and the use of an MVHR (see below) means we need a minimal amount of heating. The option we have gone for is infrared heating. 

Infrared heating panels use radiant heat and as such they are specifically designed to heat objects rather than the air. This is different to conventional central heating systems which heat air through convection (an incidentally produce air currents which distribute dust around a room). 

The heat produced by infrared systems is very similar to the heat you get from feeling the sun on your skin.

For a more in-depth discussion see https://www.homebuilding.co.uk/advice/infrared-heating

Ventilation & Air Quality

MVHR - mechanical ventilation and heat recovery is a cool technology which provides a house with a constant flow of warmed fresh air. Essentially stale air which has been warmed by every day life eg showers, laundry, cooking ... even breathing, is extracted and pumped out of the house via a heat exchanger which warms a flow of incoming air from outside.  

For a more detailed explanation see https://www.homebuilding.co.uk/advice/mvhr-the-beginners-guide

Eco paint

Water Conservation