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A-Rated homes

Not everyone looking to build a home is aware but under current building regulations every builder must now be an A-Rated builder. Better Built Homes’ practice of continued advancement ensures we are at the forefront of building techniques, therefore assuring equal and indeed upgraded standards of building.

Under recent changes to the Building Regulations Part L, all new dwellings constructed on or after 1st December 2011, must conform to new minimum standards with regards to ‘Conservation of Fuel and Energy’. There are certain transition periods for dwellings where planning was applied for prior to 30th November 2011 and where substantial work has been completed by 30th November 2013.

What is Part L Building Regulations?

The revised Part L of the Building Regulations came into force in 2011, and has heralded significant changes in the way in which buildings in Ireland are measured in terms of energy performance. This revision changed and upgraded the specification of all inputs into building design to assist in improving energy efficiency, cut CO2 emissions and result in a better Building Energy Rating (see information on this below).

 

In order to demonstrate compliance with the 2011 Revisions to Building Regulations the following criteria must be met:

  • Achieve the Energy Performance Coefficient (EPC) of less than 0.4, using the DEAP Assessment
  • Procedure for the energy rating of dwellings.
  • Minimum Acceptable U-value Standards.
  • Prevention of Cold Bridging & the limitation of Air Leakage.
  • Demonstrate an Air-tightness by testing of less than 7m3/h.m2 @ 50Pa
  • Provide 10 kWh/m2/annum contribution from Renewable Energy Technologies contributing to energy use for domestic hot water heating, space heating or cooling; or 4 kWh/m2/annum of electrical energy

 

In Summary:

 

  • Building an Energy Efficient home is not just about saving money and protecting the environment – it’s now the law!
  • By law you need a Building Energy Rating (BER) Certificate.
  • By law your new home must conform to Building Regulations that require you to demonstrate a 60% reduction in Energy Consumption from previous standards.

What is a BER Certificate?

The Building Energy Rating (BER) is a system which grades properties from A down to G by the amount of energy they consume.  A1 is the most efficient rating.   A BER certificate is based on an assessment by a trained and registered BER assessor who will take many factors into consideration:

  • Size and orientation
  • Method of construction
  • Insulation
  • Windows/glazing and doors
  • Heating systems
  • Lighting
  • Ventilation

An A-rated BER Certificate assures buyers of high energy efficiency and financial savings over a lifetime.

 

 

So why an A-rated home?

  • For a lifetime of savings on your energy bills
  • Higher resale value
  • Healthier home environment – even warmth & ventilation
  • Frost proof – minimal chance of pipes bursting or water cut-off due to extreme weather conditions
  • Reduction in harmful emissions
  • Benefits the environment and the economy

 

What is a Passive Home: 

As you have read above, building regulations are becoming increasingly stringent and will become even more so in the future. Passive homes are the way forward and all new homes will eventually be built Passive in the future. Below is an explanation of the principles of the Passive House.

The Passive House is the world leading standard in energy-efficient construction. A Passive House requires as little as 10 percent of the energy used by typical buildings – meaning an energy savings of up to 90 percent.

The 5 principals of a Passive house are:

Insulation – Increased insulation in foundations, floors, walls and roof. Triple glazed windows are also usually required.

Air Tightness – This is achieved through specialised membranes and tapes around the building envelope. Air leakage is defined as the flow of air through gaps and cracks in the building fabric. Uncontrolled air leakage increases the amount of heat loss as warm air is displaced through the envelope by colder air from outside. Air leakage of warm damp air through the building structure can also lead to condensation within the fabric (interstitial condensation), which reduces insulation performance and causes fabric deterioration. Air leakage is a ‘double whammy’ in energy efficiency terms, because warmed air leaks out and cold air leaking in then needs to be heated.

The air tightness test, or pressure testing, is a non-destructive check of unwanted ventilation i.e. drafts, resulting from poor specification, materials and workmanship. The pressure testing process supplies air to a building at a variety of air flow rates and measures the resulting pressure differentials across the building. Internal and external temperatures and barometric pressure are also measured to provide corrected airflow rate measurements. The measurements will be verified on site and results given. A full report is then issued, which will be required to confirm compliance with Part L.The aim of the testing is to reduce energy losses from the dwelling in the form of air leakage as explained above. Building owners and occupiers should experience substantial savings in heating costs as the result.

Thermal Bridging Minimised – Thermal Bridging is when an external component of the building connects to the inside of the building thus causing a cold bridge. This can be reduced through good design and construction.

Heat Exchange – A Heat Recovery Ventilation System incorporates a heat exchange unit which can recover up to and over 90% of the heat generated in the building. Heat Recovery Ventilation (HRV). With the introduction of air testing, improved thermal bridging and air sealing as well as closed flues, the necessity for heat recovery ventilation has taken on a more prominent role in today’s market. In essence, your house needs to breathe and the more air tight we make a structure the more consideration we need to give to ventilation. Heat Recovery Ventilation uses the warm air created in kitchens, bathrooms and utility rooms and mixes it, via an exchanger, to provide temperature controlled fresh air to other areas of the house. It uses a simple PVC ducted system with ceiling or wall mounted grilles. The main unit itself is usually housed in the attic with access to an external air source. Like all mechanical objects it will require a power source as well as regular servicing including filter changes etc. Some more elaborate models can also be fitted with heating and cooling coils for further enhanced temperature control.

Solar Gain – A Passive house optimises the southern exposure of your building. This can also be achieved with poor southern exposure. Large windows on the south facing elevations to maximise solar gain while reducing window sizes on the north elevations where direct sunlight is minimal. Shading also needs to be incorporated to reduce overheating in summer.

Air Leakage Diagram:

air-leakage

New Home Heating Systems:

Your choice of heating system is probably the most important decision you will make when deciding to build your new home. This system needs to be considered carefully as there are initial installation as well as annual running costs to be evaluated. Generally, the most expensive systems have the higher initial outlay but cheaper running costs and vice versa for conventional heating systems. Passive houses in principle require no heating but will always be constructed with a back-up system as a failsafe in extreme temperatures. Conventional systems on the other hand can consist of combinations of oil or gas coupled with solar and back boiler wood burning stoves etc. You must have at least one form of sustainable heating in your home in accordance with current regulations to meet a certain percentage of your annual energy demands.

Most common heating systems available:

Radiator System

This system consists of a high condensing oil or gas boiler with minimum 90% seasonal efficiency coupled with a zoned and thermostatically controlled radiator system throughout the entire house. This is a tried and tested system and with more efficient boilers on the market this system has a proven track record. The unknown factor is of course the future cost of fuel as well as negative carbon implications regarding fossil fuel reliance etc

Radiators are sized to suit individual rooms taking all factors into consideration such as room size, room aspect, amount of glazing, etc. The total BTU’s (‘BTU‘ – British Thermal Unit, the heat output in effect) of each radiator are then calculated for the entire house as well as allowances for water heating, contingency etc. to enable the correct size boiler to be fitted. An oversized boiler is as inefficient as an undersized boiler so this aspect of calculation needs to be performed as accurate as possible taking any future extensions such as attic conversions into account also.

 

Underfloor Heating System

Underfloor heating is another way of transferring heat into your home. You can connect a heat pump, condensing boiler, stove or solar to your underfloor heating system.

The floors of the house act like a giant radiator and they provide a steady, even temperature to the entire house. The type of heat from an underfloor heating system is far superior when compared to traditional radiators. A radiator system will have hot and cold zones in the house and as you walk around the house, you will be drifting from hot to cool areas. With underfloor heating, the room temperature is identical in all areas, at all times.

Many hold a misconception that underfloor heating is more expensive to run. This is actually untrue and though for a typical 150m2 house, it might drive up the cost of the heating system by around €1,000, you will have a much better heating system when compared to traditional radiators.

Also, radiators were originally designed to work with gas and oil boilers. These boilers send out water at 80°C and this heats the rads, which in turn heat’s the house. Modern homes are now being built to very high insulation standards, so people are turning to heat pumps instead of boilers. Heat pumps work best if connected to an underfloor heating system in your home.
Back Boiler Wood Burning Stove
Wood Burning Stoves, can be used to supplement your existing hot water requirements and in addition to your primary heating system. When calculated along with solar energy wood burning stoves will help to meet the current requirements of Part L in relation to renewable energy sources. This arrangement is built around a triple coil or dual cylinder arrangement and is very efficient and relatively inexpensive to install at the outset. This system along with suitable buffer tanks can also be used to supplement your underfloor heating requirements.
Solar
Solar Power as the name suggests is energy generated from the sun’s heat. Even with overcast days Solar has the ability to raise the temperature of your cylinder to some extent. Remember, every little bit helps – every degree of free heat generated by solar is a degree that does not have to be generated by your boiler or immersion.

Solar Tubes or Panels are sized according to occupancy and the requirements of Part L of the Building Regulations. They are used primarily to supplement your hot water requirements. They can be coupled with a dual coil arrangement as part of your conventional radiator system.

Best practice for siting Solar Panels or Tubes is a south facing aspect at an angle between 25 and 55 degrees.
Geothermal
Geothermal takes its energy from the ground and works on the basis that the underground temperature remains constant throughout the year as opposed to overground temperatures which can fluctuate greatly by season. Because of this Geothermal Pumps can generate heat very efficiently at a constant temperature which is most suited to underfloor heating systems.
Coupled with specific weather compensating controls and stats this system is ideal for most dwellings and has an overall payback period of between 10 – 15 years. There are two main types of collectors, horizontal collectors via pipe coils buried at specified intervals approximately 1m below ground level or vertical bored wells which range in depths of 100m to 150m. The former is least expensive in terms of installation costs whereas the latter is used where ground space is limited or specific soil conditions are unsuitable.

Air to Water

Air to Water Heat Pumps are externally mounted units that convert energy from outdoor air to heat via an internal exchanger. The principles are the same as a domestic fridge with the energy collected from the internal compartments used to heat your home through an underfloor heating network or high output aluminium radiators. These units have been used successfully in Scandinavia with extreme temperature variations. They are very well suited to the Irish climate. Although not as efficient as its Geothermal counterpart they do have a much quicker payback period.
Water to Water Heat System
This heat pump is ideally suitable if there is groundwater close to the surface on your property, due to it’s low initial installation costs and high efficiency running.

The system works by drawing water from the ground, similar to the way it is removed from a well, and passing this water through the heat pump. Energy (heat) is absorbed from the water and the water is returned to the ground via a second bore/well. This pump is suitable for all types of properties where ground and water conditions are suitable. The water to water heat pump will take care of all your space heating and Domestic hot water requirements, without the need for a backup system. Although they have certain benefits, they are very site specific and should be addressed on an individual basis for suitability.

Give us a call on +353 (87) 7873472 or fill out the contact form on our website and we will contact you.