No doubt you have heard about carbon emissions and the alleged link to global warming. This basically means ‘heat loss’ from your home due to permeation. Because most building components are permeable heat loss can be quite high so we have to do something about it.
Heat escapes through the roof, windows, walls and floors – so it goes without saying that fuel bills would be quite high if we ignored it. Fortunately we have a lot of new materials we can incorporate into the fabric of a building to prevent heat loss and in many cases we can stop it completely and this is known as “zero carbon emission”. Although most of us want to do our bit to save the planet, ecological solutions are not achieved cheaply and the lower the carbon emission, the more expensive it becomes.
UK Building Regulations have a minimum emission rate, known as thermal transmittance and these are measured in U-values expressed as W/m²K, it is simply the rate of transfer of heat through one square metre of a structure, divided by the difference in temperature across the structure.
Our job then is to obstruct the heat permeating through the building shell by introducing barriers such as insulation and membranes. Heat loss varies in each structure but we need to prevent the loss to a given level. For instance we need to achieve a U-Value in an external wall of 0.27 W/m²K and in order to do this we need to make a thermal calculation taking the wall make up into consideration. A modern wall construction, adding all the elements together could have a U value of 1.97 W/m²K – so we need to reduce this considerably. By adding various barriers we can adjust the U-Value to any lower value and achieving the minimum 0.27 W/m²K can be fairly simple by installing a given type of insulation in the wall. If we want to go lower, we can add a foil membrane and/or a secondary insulation type or foiled plasterboard eventually bringing the value down to 0.01 W/m²K zero emission.
So, the simple rule is – The lower the U-Value – The better the performance. It may cost more to achieve a lower U-Value, but it will save on fuel bills and provide you with a more comfortable home. Don’t forget it works the other way round as well – decent U-Values prevent heat ingress in hot weather, retaining the required room temperature longer without need to introduce mechanical cooling.
Fortunately, you don’t need to worry about controlling U-Values as Urban Marque Ltd will undertake thermal calculations and guarantee the levels by producing the necessary documentation to prove the values in case they are required for building control purposes.