How to Improve a Building Energy Rating

The BER of any new dwelling on the housing market in Ireland can be improved, even those (usually very expensive) houses advertised as being "A-rated".
The reasons for improving the BER of a dwelling are obvious and compelling:

the better the energy rating the cheaper your house is to run,

a good energy rating can increase the value of your house,

a house with a good energy rating is less harmful to the environment .

It is important to realise that it is only worthwhile making cost-effective changes. There would be little point, for example, in replacing good-quality double-glazed windows with triple-glazed windows if it only reduced heat loss by a small amount. The cost of doing it would far outweigh the long-term benefits. The money would probably be better-spent making improvements elsewhere.

Cost-effectiveness must be taken into account when any changes are made. Fortunately, there are many cost-effective improvements which can be made ranging from relatively simple, low-cost changes to more expensive possibilities such as the use of renewable technologies. What follows is a list of such cost-effective changes in roughly increasing order of cost.

Use Low Energy Light Bulbs

Low-energy light bulbs such as CFLs (Compact Flourescent Lightbulbs) or LEDs (Light-Emitting Diodes) use much less electricity than standard light bulbs. They are more expensive but last up to 10 times longer than standard bulbs. This is a very simple change to make and will make a significant reduction to your electricity bill and improve your BER.

Insulate the primary pipework

If you have a heating system with a regular boiler and a hot water cylinder then insulating the pipework between the boiler and the cylinder improves the BER value.

Add a Cylinder Thermostat

A cylinder thermostat regulates the temperature to which water in the cylinder is heated. The presence of a cylinder thermostat reduces Primary Losses and Storage Losses thereby improving the BER value.

Better Insulation

The amount of heat lost through the fabric of the building - i.e. the exposed walls, floor(s), roof(s), windows and doors - has a significant effect on the final BER value. The amount of heat lost through any element of the dwelling depends on that element's U-value. Ideally the U-value of each element should be kept as small as possible.

In a constructed house it is difficult to improve the heat loss characteristics of the walls and floors. For this reason it is often beneficial to calculate the heat loss at the design stage so that improvements can be made when it is still easy to make them.

Walls
At the planning stage improving the heat loss characteristics of the walls of a dwelling is straightforward. Simply put, you add enough insulation to the wall construction to achieve the desired U-value. At Atlantic Energy we can advise on the amount and type of insulation required for cost-efficient heat retention.
In a constructed house improving the U-value of the wall is more difficult. Two commonly used options are,
- dry-lining some or all exposed walls with insulated slab,
- pumping insulation into the wall cavity.
As already mentioned, even though these procedures are not particularly expensive or difficult, it is sensible to work out how much money this will save you before deciding to do it.
Floors
Like walls, improving the U-value of a floor is best done at design stage when all you need to do is increase the amount and/or quality of the floor insulation.
Roofs
Improving the U-value of a roof is simple, you just add more insulation. Atlantic Energy can advise you as to the type and amount of insulation necessary to improve your BER. Again, be aware that although you can always increase the insulation in your roof it may not have a significant effect on your BER. Therefore, it is always worth checking beforehand that adding roof insulation is cost-efficient.

Boiler Efficiency

The efficiency of your main heating system has a big effect on the BER. An increase in efficiency improves the BER. If you have a boiler with an efficiency of 80% or under it is worth considering replacing it with one of the modern condensing boilers which have efficiencies of up to 97%. This will improve the BER considerably.

Heating Controls

Improving the heating control system can reduce the BER quite significantly. There are a variety of possibilities depending on the type of heating system present.

For boiler systems the ideal is to have Time & Temperature Zone Control. To realise this level of control you need 2 space heating zones, with the temperature in each zone controlled by a Room Thermostat and a Programmer with at least 2 channels for space heating (one channel to control the heating times of each zone).

Boiler interlock

A Boiler Interlock is an arrangement whereby if there is no space heat demand and no water heating demand the boiler is switched off.
How you do this depends on what type of heating system you have.

In a system with a regular boiler you need a cylinder thermostat, a room thermostat and motorized valves. These must be wired up in a particular way to achieve the interlock.

In a system with a combination boiler you just need a room thermostat to achieve the interlock.

If you do not have an interlocked system the efficiency of the boiler is reduced by 5% which has a bad effect on the BER value.

Secondary Heating Systems

If you have a chimney with an open fire in your dwelling it is considered to be a secondary space heating system providing 10% of the space heating need (regardless of how much you actually use the fire). Open fires are very inefficient (30% efficiency) so you can improve the BER in this case by replacing the open fire with a more efficient heater, e.g. a high efficiency wood-pellet stove (65% efficiency) with its outlet flue sealed to the chimney.

An alternative is to remove the secondary space heating system altogether, i.e. block up the chimney. This will improve the overall space heating efficiency which will improve the BER. Also, heated air removed from the house through the chimney contributes to the overall heat loss from the house. If the chimney is block-up then this heat loss no longer occurs and so the BER is further improved.