By COLIN REID energy@algarveresident.com
Colin Reid is the technical director at the Enova Group and is a chartered engineer specialising in renewable and sustainable energy systems. He has over 20 years experience in the industry and lives with his wife and three children near Almancil.
In this article, we look at building design and how it plays an important role in energy conservation.
When considering energy for new buildings, it is important to understand that there is no single solution; there are a number of issues that need to be addressed.
These can be divided into two categories:-
1) The services within the building (type of heating, air conditioning, lighting, etc.)
2) The building itself (type of construction)
The issue here is that there is no point in having wonderfully efficient heating and cooling systems if all the energy is lost through the roof and walls of the building. The combination of mechanical and electrical engineering with civil engineering is, therefore, extremely important.
It is of paramount importance to ensure that your architect is talking to your services engineer at a very early stage in the project, ideally when the architect is working on the design before planning, so that any items affecting building layout such as technical rooms, risers and service routes can be incorporated into the design at an early stage.
It is also important to remember that the compulsory engineering licensing projects (also known as speciality projects) for services such as gas and water that are required at planning stage are normally inadequate for the construction phase.
The key items regarding building design that must be considered to enhance the energy performance of a building are the following:
• Shading of south facing windows – this is normally done with overhanging terraces or pergolas – it is important to filter out the summer sun but allow the winter sun through – this prevents unnecessary heat gain during summertime but allows passive heating during winter.
• Passive ventilation – good natural ventilation can actually remove the need for mechanical cooling (air conditioning) during summertime. Techniques include the stack effect where grilles are installed at low level to allow fresh air in and extract grilles at high level to allow warm air out, causing the chimney effect (a natural flow of air without mechanical ventilation). Ground cooling can also be considered where air ducts under the ground can cool the incoming fresh air.
• Passive lighting – increased glazing in strategic locations to increase the amount of natural lighting and decrease the need for electric lighting during daylight hours. Other possibilities include light tubes for basements where natural light can be transferred from the roof to the basement using specially manufactured pipes. Increased glazing needs to be done carefully to ensure that heat gains and heat losses are not increased resulting in more energy loss.
• Passive heating – using glazing where possible to allow solar heating during winter. Care is required here to ensure that this does not turn into unnecessary solar heating during summer. This can be resolved by using motorised blinds or shades.
• Thermal properties – proper roof and wall design and construction with good insulation to reduce heat losses and heat gains. Double glazing with well constructed window frames.
• Thermal mass – this is the ability of a building to store heat in the fabric during winter and coolth in the fabric during summer. Good heating or cooling systems will heat the building as well as the air within but the wall construction needs to take account of this.
The new legislation in Portugal for thermal projects now ensures that many of the measures above are incorporated into the design of new buildings.
As part of the engineering licensing phase, a new more rigorous type of thermal project is carried out which then assigns an energy rating to the building.
An A or a B grade must be achieved in order for planning permission to be granted.
Colin Reid can be contacted by phone on (00351) 282 960 969 or by email at energy@algarveresident.com. To visit the Enova Group website, click on the link to the right of this page.
