Retrofitting refers to the addition of new technologies to already existing buildings in order to improve their environmental performance. In 2015 1559,470PJ of energy where used only in residences. In these cases, energy is used for heating, cooling, lighting and domestic appliances. Retrofitting aims to modify the features of the building in order to reduce heat loss, allow for natural ventilation and increase access to natural light; thereby reducing energy costs. Successful retrofitting also increases the value of the building, makes it last longer and makes living more comfortable for residents.
Techniques for retrofitting include loft, roof, floor and wall insulation. Insulating the building reduces heat lost to the surroundings and therefore decreases energy consumption of the building as less energy is needed for the building to remain warm. Insulation materials include fiberglass, mineral wool, polystyrene and cellulose among many others. From the charts (http://info.cat.org.uk/energy-conservation) we can see that most of the homes energy (62%) is used for heating the house; reducing heat lost to the surroundings through insulation improves the thermal performance of the system therefore reducing use of energy.
Draught-proofing is also essential as a lot of heat manages to escape through open spaces due to cold air coming in. In order to reduce draughts one can use sealant paste to fill gaps and install thick curtains to avoid heat loss through windows. It is also convenient to add thermostats in order to allow for heating only in certain areas rather than in the whole building. Wrapping hot water pipes with insulating material allows for less energy to be consumed by the heating of water as less energy is lost to surroundings. It is also important to glaze windows, through which and average of 10% of heat is lost in the average home. Low emissivity argon-filled windows are the most efficient, as the glass allows for heat to be reflected back into the house and argon is a better insulator than air allowing for less heat to be dissipated into the surroundings.
Even though energy used in electricity is not a major concern (7%), we must consider that the current production of electricity is not very efficient and has a very large carbon footprint. CO2 emissions from electricity are more than double of those that come from main gas (used for heating), therefore making electric appliances more efficient is also important for the sustainability of a building. Installing low-energy lightbulbs (such as CFL or LED) is a way to reduce power used. One can also improve the quality of electric appliances such as fridges and washing machines.
Retrofitting also demonstrates to be much more sustainable than demolishing and rebuilding. As production, manufacture and disposal energy costs are higher than those of use. This means that more energy is consumed in building and demolishing than in the actual use of the building. Therefore, demolishing buildings and making more sustainable ones is not the solution; but rather retrofitting existing ones.
To reduce lighting costs you can also design buildings to allow for exposition to natural sunlight, which in turn also emits heat radiation and therefore decreases the necessity for heating. An example of sustainable housing is BedZED (Beddington Zed Energy Development). BedZED is a carbon-zero residential facility in London, which uses various technologies to minimize environmental impact. The houses are heated passively by the sun, as they count with glazed windows strategically positioned to catch the most sunlight possible. The buildings are ventilated by wind cowls, which draw fresh air from outside into the apartments. This fresh air is heated using stale air from the inside (going out) using heat exchangers.
It is pertinent to start retrofitting buildings, as the worlds’ economy is currently in a state of development and more and more people are adopting more energy-consuming lifestyles. Domestic energy consumption per capita and GDP per capita show a strong correlation. Many countries such as China and India are in a state of rapid economic growth, more people are having access to technology and heating, but buildings still show poor environmental performance. Studies conducted by the University of Cambridge show that 1billion people adopting an average western lifestyle would imply an increase of 1.43 billion tons of carbon dioxide emissions a year from the domestic sector.