Embodied energy This is the amount of energy that was used to make a material. Steel, concrete, bricks etc have high embodied energy. Timber, cork, straw etc have low embodied energy.

Retrofitting pi These are examples of different types of insulation that have been added To different types of walls and a roof space. Old inefficient buildings can be made more efficient.

Passive solar Lots of efficient glazing allows daylight in. The light energy changes to heat energy but heat energy cannot pass through glass as easily as light, trapping the warmth in the building. This is known as the ‘greenhouse effect’.

Carbon sequestration Timber Cork Hemp and lime Warmcel – recycled newspaper insulation Using plant based materials can lock up carbon in the building. Of course you would expect trees to be re-planted!

‘Sick Building Syndrome’ Synthetic materials like paint, and carpets can ‘off gas’ long after they have been installed, releasing chemicals into the environment which are bad for human health. Of course materials Like asbestos can also have implications for health. Flickering lights and poor ventilation and air conditioning can also make buildings unpleasant environments.

Breathing walls The wall is made of many layers from the interior to the exterior, including insulation. Materials have tiny holes in. In a breathing wall the most porous materials are in the inside, gradually becoming less porous so the material with the tiniest holes are on the outside. This encourages moisture to move from the inside to the outside of the house.

Ventilation Buildings need to be well ventilated to avoid stale air and condensation. But of course draughts need to be blocked! Natural ventilation systems circulate air round the building without using air conditioning through careful design. ‘Passiv’ design (like Canolfan Hyddgen) was developed in Germany. It has very rigorous efficiency standards.