Period Property - Built c 1900
Assessment carried out by: BERcerts.ie
Joseph Kearney BSc (Eng), MBA, MA, C Eng, MIEI, Chartered Engineer
Part A: Building Energy Rating of Existing Dwelling
This 2 storey detached dwelling was built c 1900. The main existing elements are as follows:
Walls: Solid brick construction, 260mm thickness with pebble dash finish, plastered internally.
Roof: Tiled pitched roof, with 25mm fibreglass insulation between the ceiling joists.
Windows: Wooden single glazing windows throughout with estimated u-value 4.8 W/m2 K
Floors: Suspended Timber tongued and grooved floor with 200mm space under floor
Heating: External oil fired boiler supplying an un-insulated 95L cylinder fitted with a dual immersion and timer. Space heating is via radiators. There are also 2 fireplaces in the dwelling acting as secondary heat sources
There are 3 intermittent fans or passive vents
Comments
Carrying out the recommendations listed below will lead to vast improvements in the comfort levels of the property, with heating bills reduced significantly.
Part B: Improving the energy rating
Chimneys – highly recommended
This dwelling has at least one chimney. An open coal fire is approx 30% efficient and a gas fire is 20% efficient. Chimneys increase heat loss in a dwelling by allowing approximately 70% of the energy in the room to escape, adversely affecting the BER rating.
There are typically 3 upgrade options available.
(a) Installing a closed-in stove (costing between €600 to €6,000 depending on the product) will reduce heat loss, being approximately twice as efficient as an open fire. The BER rating is also greatly enhanced.
(b) Jetmaster - a high efficiency fire with a damper can be installed keeping the open fire effect but improving the efficiency from 20% to 55%. This re-directs heat that would normally go up the chimney back into the room. Approximate cost > €2,500.
(c) Chimney Closure - If one prefers not to replace the existing open fire, then a closure device may be installed allowing the chimney to be closed when not in use. This will reduce the heat loss of a single room by up to 70%. Cost approximately €350.
Building Elements
Floors – highly recommended
This dwelling has an unsealed suspended timber ground floor. This type of floor can have a significant impact on the heating bills due to constant air infiltration between the joints in the floor boards. Combined with the inefficient fireplace the result is that cold damp air is pulled from beneath the house into the room and up the chimney. There will be a constant chill in the air even when the heat is on full.
Installing insulation will reduce this heat loss, and so reduce the energy demand of the dwelling.
One option is to insulate between the joists and place down a vapour barrier resulting in the floor now being insulated and also sealed from air infiltration. This will dramatically improve the living conditions throughout the house. Fixing approximately 80 mm of polyiso-board between the floor joists and then replacing the original tongued and grooved timber flooring will keep the original look.
Roof Insulation
The roof is 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 existing visible area has insufficient fibre glass insulation and should be increased to 300 mm. 100 mm of insulation placed between the joists with the remaining insulation placed in the opposite direction over the joists will bring the u-value to 0.15 which is lower than the current building standards.
Walls
These type of walls may be difficult to insulate for a variety of reasons. If there is a decorative coving on the ceiling one may wish to keep this intact, therefore external insulation would be ideal. However, if it is a preserved building the only option may be to insulate internally.
Installing insulation will reduce heat loss, help reduce thermal bridging and so reduce the energy demand of the dwelling.
If the external walls are insulated correctly then the u-value can be decreased to 0.27 to comply with the building regulations. Comfort levels will be dramatically improved and the cost of heating the building will be reduced. It should be noted that installing external wall insulation needs to be carried out by a professional. The area of cold bridging is significantly reduced by external insulation as it covers the entire house like a glove.
Windows
Heat loss through windows in older buildings can be significant as they have relatively poor thermal performance compared to other elements of the building. Installing energy efficient windows such as low-E double glazing helps to retain heat and improve comfort levels through elimination of cold window surfaces, condensation and associated downdraughts. The use of shutters, lined curtains and blinds can improve heat retention at night and further reduce downdraughts.
The existing wooden windows have high heat loss, therefore replacing these to achieve u-values of 1.6 or less is recommended, while also eliminating any existing air infiltration issues. Sash windows with this u-value and lower are now available.
Lighting – highly recommended
All lighting should be replaced with low energy lighting. Replacing all the light bulbs has a payback of approx 1 year and will dramatically reduce the lighting bill.
Central Heating, Hot Water & Zone Controls
Installing a full zoning system in the house will significantly improve the BER rating and also reduce running costs. If the house is being refurbished this can be easily achieved.
For the Space Heating zones a Timer in conjunction with a Thermostat and Motorised Valve can be installed.
Heating Zone 1: A thermostat can be placed in the hall/corridor for the zone
Heating Zone 2: A thermostat can be placed in the landing/corridor for the zone
Hot water flow to the radiators is controlled by the thermostat which signals the relevant motorised valve to open or close as required. Furthermore the timer will allow the zone only to operate according to programmed times.
The Hot Water circuit can also be fitted with a Timer in conjunction with a Cylinder Thermostat and linked Motorised Valve. This thermostat operates to prevent the hot water from increasing above the desired hot water temperature for occupant use.
Together, this will then allow full control of the space heating and hot water zones.
Hot water cylinder insulation & Immersion – highly recommended
The existing hot water copper cylinder is not insulated. Consider replacing it with a larger pre-insulated cylinder model (160L capacity or more)
If an immersion is fitted then a timer must be also be fitted to comply with the home energy scheme grant. This can be part of the heating controls upgrade package.
Radiators and Thermostatic Radiator Valves (TRV) – highly recommended
There are no TRV’s on the radiators in the dwelling. It is recommended that TRV’s be installed on all radiators to increase comfort levels and achieve a better rating. A minimum of 3 TRV’s are required under the new Home Energy Scheme. Replacing the old radiators with a more efficient modern version which hold up to 50% less water will emit heat more readily, thereby using less energy.
Boiler Energy Saving System – highly recommended
A digital boiler management system such as an Energy Master may significantly enhance the energy rating and also save between 20 - 30% on the fuel bill per annum. It uses the principle of Variable Thermal Response (VTR) and Auto Weather compensation software to achieve its energy savings. It significantly reduces fuel wastage caused by temperature overshoot, heat saturation of the heat exchanger, flue losses, and unnecessary boiler cycling, whilst improving internal comfort levels.
Boiler Interlocks – highly recommended
No boiler interlock was found. The provision of a boiler interlock improves the BER rating and is covered under the SEI Home Energy Scheme for grant assistance. The Energy Master system mentioned above will provide this facility. It is not a physical device but an arrangement of the system controls so as to ensure that the boiler does not fire when there is no demand for heat.
Efficiency of main heating system – highly recommended
This dwelling has an external oil boiler heating system with an estimated efficiency in the region of 65%. An additional saving of approx 25% could be realised if the existing boiler is replaced with a condensing boiler. A Condensing gas boiler can obtain > 90% seasonal efficiency, while a condensing oil boiler can obtain > 95% seasonal efficiency. The replacement cost is approximately €3,000.
Assuming all the recommendations (recommended or highly recommended) are carried out then a greatly improved rating can be achieved as seen by the BER certificate seen below: