Building Energy Rating (BER) Case Study 1:
The dwelling was inspected by Joseph Kearney BSc (Eng), MBA, MA, C Eng, MIEI of BERcerts.ie on the 27/03/09.
Part A:
Summary Specification - Existing Dwelling:
· The house was built in 2000 and is a detached single storey dwelling.
· The house is of a cavity wall construction.
· The total area of the house was calculated to be approx 190 m2.
· The attic space over ceiling has 100mm fibre glass insulation between joists.
· The windows are PVC double glazing windows throughout.
· The heating is supplied via an internal oil boiler.
· There is 1 fireplace in the dwelling – also used a secondary heat source.
· No low energy lamps for lighting were found.
The Building Energy Rating of the above dwelling is currently: E1
Link to Table of Proposed and Current Values
Part B:
Steps that can be taken to improve the rating:
Chimneys
This dwelling has at least one chimney. An open solid fuel fire is approx 30% efficient and a gas fire is approx 20% efficient. Chimneys increase heat loss in a dwelling by allowing heated air to escape. Approx 70% of the energy in the room escapes up a chimney. Therefore an open chimney has an adverse effect on the BER rating.
Here are 3 of the upgrade options available:
(a) Installing a closed-in stove will reduce heat losses, and will also be approximately twice as efficient as an open fire, giving the same heat for half as much fuel. The rating is also greatly enhanced. Approx cost €600 to €6,000 depending on product.
(b) Chimney Closure - If one prefers not to replace the existing open fire but wishes to reduce heat loss when the fire is not in use, a chimney closure device may be installed.
(c) High Efficient fire with a damper can be fitted can be installed, keeping the open fire but improving the efficiency from 20% to 55%. This re-directs heat that would normally go up the chimney back into the room.
Draught Stripping
Fitting draught proofing around attic hatches, pipes, etc. which are not draught stripped will reduce unwanted ventilation which causes heat loss and draughts in the dwelling.
This can also prevent warm moist air entering the roof space which can lead to possible condensation and rot.
The existing weather stripping on windows should be examined and replaced if necessary.
Roof Insulation – highly recommended - (a grant of €250 is available from the Home Energy Saving Scheme).
The roof can be one of the largest heat loss areas in a dwelling. Installing insulation will reduce this heat loss, and so reduce the energy demand of the dwelling.
The building regulations have specified a u-value of 0.16 or lower, since 2002, which can be achieved using 270 mm of fibre glass or more.
Walls
As often the largest surface area, the wall can make up one of the largest heat loss areas in a dwelling. Installing insulation will reduce this heat loss and can help reduce thermal bridging and so reduce the energy demand of the dwelling.
Option 1) Cavity fill insulation – (a grant of €400 is available from the Home Energy Saving Scheme).
If the walls are pumped with the appropriate insulation type then the u value can be decreased to 0.26 W/m2 K to comply with the building regulations.
The cost for this type of insulation can be low with a grant of €400 available.
Option 2) internal insulation – a grant of €2,500 is available.
If the external walls are insulated using plaster board backed with a specified thickness of polyiso rigid board then the u value will be decreased to 0.27 W/m2 K from the initial value of 0.71 W/m2 K.
Central Heating, Hot Water & Controls - highly recommended
For the Space Heating zones a Timer in conjunction with a Thermostat and Motorised Valve should be installed.
The Hot Water circuit could be fitted with a Timer in conjunction with a Cylinder Stat) and linked Motorised Valve. This will allow full control of the space heating and hot water heating zones.
The above controls are covered under the new Home Energy Scheme for a grant available from the SEI. The total grant available is €500 for heating controls.
It is recommended that Thermostatic Radiator Valves (TRVs) be installed on all the radiators throughout the house increase comfort levels and achieve a better rating.
Efficiency of main heating system
If the efficiency of the boiler is less than 80% or more than 10 years old then replacing it with a high efficiency condensing boiler could be considered. Advice should be sought on this step.
The cost of replacing a boiler is approx €3,000. There is also a grant of €700 available under the Home Energy Scheme for installing a high efficiency boiler with heating controls.
Hot water cylinder insulation
If the cylinder is reaching the end of its useful life or is too small, consider replacing it with a pre-insulated cylinder model of at least 50 mm of insulation or more.
Floors
Floors can be a source of significant heat loss and dampness in a dwelling. Installing insulation will reduce this heat loss, however, it should be noted that installing floor insulation generally involves a considerable amount of work.
Windows
The standard PVC double glazed windows, fitted since 2000, with a 16 mm gap between the glass panes will more than likely have a u-value of 2.7 or lower.
Aluminium windows and single glazed and older double glazed windows will have a much higher heat loss and should be replaced. When considering windows it is recommended that a u value of 1.6 or less is used.
GLOSSARY
U-Value is the measure of heat loss or gain in watts per m² of area due to the differences between inside and outside air temperature. It is measured in W/m²K. The lower the figure the better.
Motorised Valve
A Motorised Valve is used to control water flow from the boiler to the heating and hot water circuits and is operated electrically. Motorised Valves are used with fully pumped systems. Two-port valves can also be used to provide zone control, eg lower temperatures in sleeping areas or different heating times.
Cylinder Stat
A Cylinder Thermostat monitors the temperature of the domestic hot water. A Cylinder Thermostat switches the heat supply from the boiler to the hot-water cylinder on and off. It works by sensing the temperature of the water inside the cylinder, switching on the water heating when the temperature falls below the thermostat setting, and switching it off once the setting has been reached. The Cylinder Thermostat is strapped onto the hot water cylinder between one quarter and one third of the way up. Cylinder Thermostats should be set to about 55-60°C.
TRV
Thermostatic Radiator Valves (TRVs) sense the air temperature around them and regulate the flow of the water through the radiator. They help improve comfort in your home by allowing you to set different temperatures in different rooms. The Thermostatic Valve will maintain the temperature of the room you have selected by automatically adjusting the heat output from the radiator. Thermostatic Radiator Valves have a range of temperature settings. This also helps to save money and energy.