Author Archives: Greener Space

If your house was constructed using cavity walls you could benefit hugely by having this cavity filled with insulation.

1. The process involves drilling holes into the mortar joints at various points around the house.
2. Insulation fibre or a similar material is then sprayed under pressure to fill the cavity.
3. The holes are then filled.

If this process is carried out properly, you could reduce the heat loss from the walls by up to 75%.

A major benefit of this process is the low level of disruption to the interior and exterior of the house. It is also a relatively inexpensive way to insulate your home.

Insulation is the most important part of having an energy efficient home.
Good Insulation, properly installed can save a huge amount on your energy bills and increase your home’s energy rating significantly.
Some types of insulation are:

Mineral Wool
This type of insulation can be found in attics in most houses in Ireland. It has a low conductivity and is a good insulator in large quantities. 300mm thickness is generally recommended for new construction standards.

Sheep Wool
Sheep wool has similar conductivity values to mineral wool but is far more expensive. The main advantage is that it is a renewable material.

Phenolic Insulation Board 
This material has a lower conductivity value and hence is better insulator than mineral wool. These materials are quite expensive, but are used in areas where space is a premium.

Conductivity of an Insulating Material: 
Insulation has a conductivity value which tells you how good an insulator it is, this value is generally quoted as lamda ( λ ). The lower the conductivity value the better the insulator.

U-Values: 
U-Values are often quoted by builders and architects in relation to an insulated area.
U-Values tell you the degree to which your walls, floors and roofs are insulated.
The lower the U-Value, the better the insulation.

The installation of a wood pellet Boiler is similar to that of any central heating boiler or stove. It requires a flue and a fresh air supply to be installed for safe and efficient combustion. Stoves contain an integrated fuel hopper that must be filled manually. Once full, the hopper automatically supplies fuel to the stove, allowing it to operate independently for around 20-40 hours.

For boilers or larger systems which require a greater fuel input, you may decide to site your storage facility adjacent to the boiler and install a completely automatic fuel feed system, such as an auger, so that you do not have to re-fill the hopper manually.

The main benefit of these systems are:

• Wood is a “carbon neutral” fuel
• Installing a wood pellet boiler in your house can reduce your carbon emissions by two thirds.

Wood pellet systems can have a high net efficiency of about 93%.

To give a general idea of price – the cost to supply and install a 25kW system in your home would generally be in the region of about €13,000 including VAT.

There are currently two grant programmes available to homeowners through SEAI (The Sustainable Energy Authority of Ireland):

The Better Energy Homes Scheme provides grants to homeowners who invest in energy efficiency improvements in one or more of the following areas: Roof Insulation, Wall Insulation, Installation of a High Efficiency (> 90%) Gas or Oil fired Boiler, Heating Control Upgrades and Solar panels.

The Warmer Homes Scheme (WHS) aims to improve the energy efficiency and comfort conditions of homes occupied by vulnerable households in receipt of the National Fuel Allowance Scheme through the installation of draught proofing, attic insulation, lagging jackets, low energy light bulbs and cavity wall insulation where appropriate.

Passivhaus buildings provide a high level of occupant comfort while using very little energy for heating and cooling. They are built with meticulous attention to detail and rigorous design and construction according to principles developed by the Passivhaus Institute in Germany, and can be certified through an exacting quality assurance process.

The new-build Passivhaus Standard requires:

• a maximum space heating and cooling demand of less than 15 kWh/m2.year or a maximum heating and cooling load of 10W/m2
• a maximum total primary energy demand of 120 kWh/m2/year
• an air change rate of no more than 0.6 air changes per hour @ 50 Pa

The Passivhaus refurbishment standard, EnerPHit, requires:

• a maximum space heating and cooling demand of less than 25 kWh/m2.year or a maximum heating and cooling load of 10W/m2
• a maximum total primary energy demand of 120 kWh/m2/year + heat load factor
• an air change rate of no more than 1.0 air changes per hour @ 50 Pa

To achieve the Passivhaus Standard in the Ireland typically involves:

• very high levels of insulation
• extremely high performance windows with insulated frames
• airtight building fabric
• ‘thermal bridge free’ construction
• a mechanical ventilation system with highly efficient heat recovery

The heating and hot system controls are quite basic in most older houses, leading to huge inefficiencies in their use.

Controls include:

• Room thermostats in the house
• TRVs (Thermostatic Radiator Valves)
• Cylinder Thermostat (the hot water cylinder will turn off when it reaches a certain temperature)
• Boiler Interlock (the boiler turns off when the house reaches a set temperature)
• Programmer (to heat the house and hot water at specific times during the day)
• Zone control (where there are separate zoned areas which can be controlled independently)

In older houses improvements can be made by installing a room thermostat, boiler interlock and some TRVs on radiators. A cylinder thermostat and programmer can also be installed.

Using the boiler exclusively as the means to produce hot water for the house also reduces the energy used significantly.

Newer houses should have time and temperature zone control which requires plumbing different areas of the house on different loops, enabling thes areas to be controlled independently.

Solar water heating systems use the energy of the sun to heat the hot water for your home.
They contain a number of components:

• A collector (there are 2 types: flat plate collectors and evacuated tubes)
• A cylinder (this is much like an existing hot water cylinder but it is much larger as it contains 2 coils – one from the collector and one from your heating system)
• A control panel (this controls the temperature of the water and introduces heating if required)

Solar water heating is most effect on a south facing roof, mounted at a 30 º tilt. It can supply most of the hot water needs of a household if sized correctly.

Grants are available from SEAI ( see here). These systems usually have a payback period of 5 to 10 years.