Two architects discuss their energy-efficient designs with Emma Cullinanin light of the new law that requires homes to be energy rated when they are put up for sale.

A HIGHLY INSULATED house in Monastery Cross, Co Cork, has wonderful views over the countryside and garden, whose plants were mainly kept intact during the build.

This is Wain Morehead Architects' third house with timber frame company GriffnerHaus (formerly Griffner Coillte) which they like because the company guarantees thermal efficiency of windows and walls, and because the latter are breathable: "These homes can operate at up to three degrees less than a conventional house - maintaining an acceptable level of comfort - due to their low humidity levels," says architect John Morehead.

He built a timber frame house for himself in 2003 and says that he understands more and more about sustainable design with each build. "Our housing designs have always had a sustainable and energy-efficient lean and the more projects we complete the more we learn and can incorporate into the next projects."

The house at Monastery Cross, like those before it, has double-height spaces, carefully placed windows and wind-bracing walls; so that the house catches natural light and sun while sheltering from wind chill. Outside the house has overhangs in key spots to allow for sitting out at many times of the year.

The practice is guided in this by Scandinavian design, says Morehead, which allows those in a northern climate to be comfortable both inside and out. Even the solar panels, that supply hot water and underfloor heating, in the garden, cover a Scandinavian-like log pile. Our warm spring, he says, even allows many of his clients to have all their hot water supplied by the sun's energy.

For times when houses actually get too hot, Wain Morehead designs in stack-effect ventilation (which means that warm air is sucked out of the building through high-level openings).

The design of such energy efficient homes requires plenty of thought at the outset, says Morehead, because, with much of the house being factory made and effectively delivered on a lorry, last-minute changes are not an option. "It gets clients and architects thinking way ahead and is just the same as when you buy a car - if you ask for brown leather seats, you can't change your mind after delivery."

With CAD (computer aided design) such early-bird design decisions - including the eco-friendly parts - is much easier, says Morehead, because you get to see your house in a virtual world before it is built.

Wain Morehead Architects is a BER (Building Energy Rating) assessor company so will be able to check out buildings under the new law but it also means that Morehead can keep a check on standards during the practice's own builds and "design those things in during the design process instead of afterwards".

The law coming in on July 1st will apply to commercial companies and the owners of this house have already commissioned Wain Morehead to create them a sustainable office: "They were fantastic and enthusiastic clients from the outset," says Morehead.

"Our house is too warm"

Neil Burke-Kennedy has had one complaint from the clients of a house that he designed in Dublin 4: the home is so warm that they have to leave doors open which can lead to security worries. But they jest, as they were keen for a house that was cosy and energy efficient: "We lived in a large Victorian house for many happy years, despite the problems associated with it, in particular the high fuel bills and draughty cold winters, and were excited to create a house with as low a carbon footprint as possible."

Burke-Kennedy enlisted the help of construction company Meisterwerk on this build, which includes a timber external wall with 205mm of insulation made from recycled newspapers mixed with liquid and sprayed into the wall cavity (covering the plumbing and electrical pipes set in there).

Burke-Kennedy has used this type of insulation before, for instance, in his own holiday home in Sligo which was also built with a timber frame.

Both homes use geothermal heat (from the ground) to bring the water up to a certain temperature (around 13 degrees) and combine that with underfloor heating. Such systems work best with underfloor heating as this needs a constant temperature of around 30 degrees while radiators use about 60 degrees, says Michael Dineen of geothermal company GroundSource. Such systems, used with underfloor heating, can also take advantage of night rate electricity.

In Sligo, Burke-Kennedy used geothermal heat, sourced through a 160m bore hole, which, as he points out, is like a modern - and inverse - form of the traditional telegraph pole. When getting a quote for geothermal heating you need to add in the costs of the floor structure, with its insulation (and, when retrofitting, taking up the existing floor), says Burke-Kennedy.

In the Dublin house he used a solar system to heat the water which has gas on stand-by to kick in when the need arises (known as a Rotex Gas Solar hybrid system). This house also has a heat recovery system which collects warmth from mainly damp quarters, such as kitchens and bathrooms, clears out the nasty air, gathers in fresh air and pumps it back into the house. These are often put into attics with ducts running into each room.

Both houses - which are orientated to benefit from passive solar gain through large glass windows - have rainwater collection, in which water gushes along downpipes into tanks in the ground and is then pumped out to be used for flushing loos and in washing machines.

While eco-buildings can incorporate all of the latest sustainable elements, they won't work efficiently if the build quality is not good and there are cold bridges and draught gaps. To guard against this, in the Dublin house, the architects ran dyed air through the structure to identify any gaps, which were then filled.

In such houses you can really tell the difference, says Burke-Kennedy. "It is like the difference between an old Mini Minor and a new Porsche. You can walk in, in January, and have a nice dry, really comfortable heat. We have a level of comfort that was missing in our old home," says one of the Dublin 4 clients. "The result has been a great success."