Frequently Asked Questions

• General Questions
• Greenhus Service Questions
• Construction Questions
• Energy Questions
• Cost Questions

General Questions

It is a philosophy of house construction. It integrates sustainability and good ecological practices of the construction of the house, the quality of the house with the quality of life in the house.

It has been developed by Kennet Karlsson, the founder of our Swedish sister Company, Karlsonhus Industrier, to provide a building system for the future well being of the world. It combines a building system that is good for the world that gives good 'Healthy' houses for us to live in.

• It uses minimum quantities of the worlds non sustainable resources
• It uses minimum quantities of materials that have to be manufactured
• It uses materials that enhance for Bio- diversity
• It uses as great a quantity of re-cyclable materials as possible.

Ekomer challenges us to realise that this standard of building gives the quality of life experienced by the family in their home as their true Capitol Asset not the theoretical financial value

Every building system has a theoretical u-value. This is made up from all the constituents: each window has a u-value; the wall section has a u-value etc.

The wall u-value is calculated by the analysis of the construction of a x —section of the wall, roof and window.

This is the theoretical value not the actual value is that achieved on site by the builder. It is easy to see that a wall constructed on site with all the variables of weather, man failure, 'knock off home tomorrow's Saturday' attitude is less likely to achieve the theoretical u-values, poor workmanship will considerably reduce the efficiency of the house.

If the walls are built in a factory then it is much easier to maintain a strict quality control and therefore the client gets a house with the actual u-value the same as the theoretical. The house performs as expected.

Open panel systems are quick to build, therefore cheaper for developers. In simple terms open panel systems are good for developers and closed panel systems are good for the occupier.

Mineral wool and Rock wool are the same; they are made from stone. Mineral Wool is the generic name; Rock Wool is a Brand Name for a Mineral Wool product. We us where possible rigid 'bats' building without compressing it, with handprints, so ensuring it's theoretical u-value

This is one of the most sustainable insulation materials as it is manufactured from recycled newspaper. Pumped into the wall and roof sections under pressure it ensures there are no cavities in the insulated layer that could cause a dew point.

It is fully breathable and will allow moisture to pass through and escape without damage to the building envelope.

It also helps with the air-tightness of the building.

All houses are susceptible to weather. Most block houses have at least 60% of it's fabric as timber, roof structure, floors etc. If a block built house is poorly maintained it will have problems. The imperative for all houses is to maintain them properly and keep the damp out. If you do this then you will have no problems. The forced air ventilation system in our house prevent any build up of humidity in the house, there is never any condensation.

They last as long as they are maintained. All houses require a new roof or window etc. as years go by. Ours are the same. Maintenance is the name of the game. Insurance companies regard them as 'permanent' structures and the insurance premiums are the same as for block houses.

Most fires are started by a fault in electrical goods, wiring or a mistake that has taken place within the home.

It is a mistake to think that a block built house is very different. Nearly 60% of the structure of a block built house is timber, floor, joists, roof structure etc. All this timber is normally safe behind plaster board — a fire barrier. That is the same with Greenhus houses.

In the most unfortunate of cases if the building catches fire completely the timber house will indeed burn down if not quenched. In a similar situation the Block house will be gutted and the walls will have to be pulled down as it's strength, the mortar, is compromised by the heat of the fire.

The block built house does not afford you any further protection from fire. Prevention: good wiring, well-maintained appliances and common sense are the reasons why there are very few houses burnt down.

Greenhus Service Questions

Yes, from doing all the ground works to hanging the curtains.

Both, but we are an Irish company with an Irish based labour force. The Swedish company, Karlsonhus, has trained our labour force.

16 weeks from order to delivery on site.

3-5 days to erect on site.

Approximately 13 weeks to fit out and finish for client to walk in.

No, Greenhus must erect the frame and make the building watertight and air tight to allow you the Premium Guarantee New House Building insurance. But the client can finish the house from that point.

We can build to your plans or we can help with a design that we already have. This can be adjusted if required to suit your needs.

We also have an association with an Architect Practice to assist with House Designs and or planning applications, if these are needed.

No not at all. Greenhus does require that all sub-contractors are fully qualified and are shown how to work on our buildings.

Also they must have all insurances and 'Health and Safety' qualifications, passes, etc. to satisfy current regulations.

We would encourage the use of local electricians and plumbers, as they will continue to be available to the client as a 'Support System'.

Construction Questions

Yes, we use a Passive house system, SuperGrund. It is a polystyrene raft system guaranteeing no cold bridging between the house and the ground through the foundations. We do not mind if the initial ground works are carried out by the client's own subcontractor but all these works will need to be checked by an engineer before we install the foundation system.

It is much harder to build a 'super-insulated' house from blocks.

A timber house will always be warmer. A timber house is 'kinder' on the world. Vast quantities of energy are required to manufacture cement.

A ton of cement puts a ton of CO2 into the atmosphere. A ton of sustainable timber used takes half a ton of CO2 out of the atmosphere.

We can apply render, stone work or timber as an exterior finish, which ever is required by the Architects design and satisfies the planning requirements.

At present we use a high performance Acrylic render system with a recycled glass carrier board by STO.

This is the real concern in the construction of timber frame housing.

If you get an air pocket where insulation has been poorly installed or a badly installed air tight membrane.

Cold air will pass into the wall section at these points and condense within the structure, This is the Dew Point. This in time can cause rot!! You see why the quality of construction is so important.

Swedish pine from the north of the country. It takes 95 years to mature before cutting, compared with 20-23 years in Ireland. It is in effect a semi hardwood.

A conventionally built house 'leaks' so much air that it changes it's volume of air 4-7 times/ hour. You then have to replace that 'escaped' warm air with more heated air: Hence high fuel bills. If you seal the house and control the number of air changes, then you manage the heating much more efficiently, your heating bills are reduced. It is now accepted that this is one of the most significant elements is constructing a Low Energy House.

Energy Questions

It is a unit measurement to demonstrate the thermal efficiency of the various parts of the building. Ie. Window, wall, and roof section etc.

As the structure is a draft proof structure there is no natural ventilation when all the windows and doors are shut. It needs a forced air ventilation system. In it's simplest form it changes the air in the house every 2 hours and takes 90% out of the exhausted air and puts it into the new fresh air.

A Low Energy House is draft free and needs a ventilation system. A normal block built house has drafts and the air is changed without control. All the heat goes out with the draft. An ultra low energy house controls the air change. It is a completely different way of looking at heating. Instead of worrying about how to heat the house you concentrate on reusing the heat/ energy that you already have in the building — the cheapest heat is the heat you have already paid for. With this system, the actual heat source is so small it becomes very less important than normal.

This is a structure that has a heat load (energy requirement of a maximum of 15kw hr/sm/yr). In other words it is so well insulated and the energy within the house is stored so well that it requires only the minimum extra energy to heat water etc.

The space heating is looked after by, solar gain through windows etc., the human activity within the building (each person gives off nearly 1/3 kw.), cooking, showers etc all give off heat to the house. Only the very smallest amount of energy will be required for the Irish weather to maintain the necessary heat levels in the house.

It is then recycled time and time again using the heat recovery system. Water heating is achieved with solar panels, small boiler and with a heat pump linked to the ventilation system.

It is very difficult to construct an Energy Zero house free building on site. We have seen how the problems of on site construction can seriously prejudice achieving theoretical u-values. While this is a disadvantage for a Low energy House it is critical for an Energy Zero house — It will fail as an Energy Zero house and will not work as such!

A closed panel construction can guarantee the performance of a building. All buildings designed as Energy Zero structure, if built using a closed panel system, will be a passive structure.

It is a machine, which transfers heat (energy) from one medium to another. I.e. we can link a heat pump to the heat recovery system (forced air ventilation system). If the house is already very warm the house does not need the heat from the exhausted air put back into the house to further raise the temperature. We do not want to lose this heat (energy) so we need to find a way to store it for future use. We can do this by linking the HRS to the heat pump and the unwanted energy is put into water (Heat store or heat sink) for future use as space heating or domestic water.

Geothermic heating systems use a heat pump to take the heat from the ground to use within the house. Air to Air heat pumps work by taking the ambient energy within the air temperature and putting it into water.

Yes, if the house design and customer requirements are correct. But is a very expensive system for a house that requires so very little energy for space heating.

Not really. The houses are very sensitive to over heating. The problem with under floor heating in our climate is the extreme variety of temperatures from hour to hour, day to day. So we need a system, which can deliver heat quickly, and precisely on demand. Under floor heating is too slow to control, too inaccurate. It will continue to deliver heat after the house has told the controls to switch off: this is a waste. It is fine for a climate where the temperature stays the same for long periods of time. Small radiators are the best at doing this.

Our climate, in the Spring and Autumn tends to give a warm day followed by a cool day. Under floor heating cannot react quickly enough to deal with this, It tends to 'lag behind', reacting to the day before.

Wood pellet stoves are the same as anything else; there are good ones and bad ones. The grant that was available for these boilers has encouraged the purchase of the cheaper boilers. You have all seen the person buying wine in France, obsessed by finding the cheapest and then thinking they have done well in buying it. They get it home and surprised it tastes like vinegar!

Buy the best you can afford, not the cheapest.

The other reason pellet stoves have not performed is that for a conventional house they burn very large volumes of pellets to replace an oil boiler. You need a large store and bulk delivery. The level of humidity of the pellets is critical to the efficiency of the boiler. Poor storage can severely reduce the performance of the boiler.

A low energy house uses much fewer pellets so can be bought in bags to guarantee the quality when required.

Yes, they give you all the hot water you will need in the summer months and a very useful contribution throughout the rest of the year. Space heating is not the main energy requirement of a Greenhus house; Hot water is the greatest energy demand in a family house. While, at present, it may not be absolutely possible to say that Solar panels are a good economic solution they will become the norm very shortly as fuel cost continue to rise.

Again the advice is: Buy the best you can afford, not the cheapest.

Cost Questions

It can be hard to compare with a block built house. Most Block built houses have 'a cousin to do the blocks, a brother to do the roof etc. etc.' If it were built by a Main Contractor then we are approx 18% more expensive. But this is difficult to quantify in the current climate.

There was a time not long ago when all this extra cost was hard to justify in the savings on your heating bill. It has always been a good thing to do ecologically but hard to justify financially.

1. Fuel oil is now definitely going to start becoming much harder to get, hence more expensive.
2. More and more people are becoming anxious about the well being of the world.

This had had the effect of making the fuel savings better and more cost effective.

The greater effect has been the interest in low energy housing. There is now a premium on the resale value of an Ultra Low Energy house with the expectation of the energy 'passport' required on all housing. The house, which can demonstrate how little it costs to heat, will demand a premium over another that is not as efficient. In the future, it will be much harder to sell for the same price, a block built house that might cost €5000 / yr to heat compared to an ultra low energy house costing no more than €500 / yr. to heat.

Remember a closed panel building system guarantees these performances, other systems hope to!

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