Passive Homes Ireland 2021 - All you need to know
What is a passive house and what can it do for you? The housing crisis over recent years in Ireland is pushing the Irish housing market to ever-expanding new limits, but are we making sure all new housing is an investment in our future, or digging ourselves deeper into a pit of carbon debt?
What is a passive house?
A passive house (also called by the German name Passivhaus) is not actually a type of house, it’s a standard for energy efficiency. Passive houses are typically ultra-low energy buildings that require minimum energy in order to stay at a comfortable temperature during winter and summer.
As a housing standard and not an actual type of housing, passive house design should be integrated with architectural processes when building houses. Due to the intensive nature of the changes required to make a house of passive house standards, it is normally applied to new builds, although some older houses have also been successfully refurbished a lá passive house style.
The majority of passive houses have been built in Germany, Austria, and Scandinavian countries, although their popularity throughout Europe is growing. Passive house standards as we know them originated in 1988 as part of a collaboration between Bo Adamson from Swedish University Lund, and Wolfgang Feist from the German Institute for Housing and the Environment.
Since then, it has been developed upon and researched. The first examples of the passive house standard were constructed in Germany in 1990. To date, thousands of houses incorporating passive house design have been built, estimated at more than 25,000 in 2010. It was not until 2010 that a refurbished house was awarded the passive house standard.
Ireland’s dance with passive housing began in 2005, built by Tomás O’Leary, and named “Out of the Blue”.
What standards does a passive house need to meet?
Passive house standards require several requirements in order for a building to be deemed passive house. These requirements include:
- Heating and cooling demand of the building must not exceed 15 kWh/m2. So if you have a small 200m2 semi-detached house, for example, you shouldn’t use more than 3000 kWh per year. In Ireland, the average gas usage per year is at around 11,000 kWh, so this represents a big drop.
- Total energy consumption (including electricity) must not be over 60kWh/m2 per year. If we use the same example again of a semi-detached 200m2 house, average consumption should be 11,000 kWh or gas and 4,000 kWh electricity a year, so 15,000 kWh. A passive house should not use more than 12,000kWh maximum.
- Air must not exit the building at a rate of more than 0.6 times the house volume per hour. A blower door ( a machine to test the airtightness of a building) can and should be used to evaluate the house complies with this standard.
As you can see, these are some pretty specific standards you are unlikely to achieve with a bit of duct tape and some insulation. If a building meets these standards, they should, in theory, then be able to dispense with a regular heating system. They will still need a heating top-up though, so most Passive house buildings use heat recovery systems and also heat the air passing through the ducts when needed.
How does a passive house work?
So above we looked at some of the standards that need to be met in order to call a house a passive house. Now let’s look at what you can do to a house in order for it to be able to meet those standards. The main areas to focus on and improve upon include:
- Lighting and electrical devices
- Space heating
Passive house standards mean that buildings must be much more airtight than the norm. A building being airtight means that it is much more likely to maintain an intermediate temperature, and not be influenced so much by external conditions. Passive houses increase their level of airtightness through the use of air barriers and heat exchangers.
Lighting and electrical devices
Natural light is maximised in passive houses to reduce the amount of energy expended on lighting. For any areas of the house without natural light, at nighttime, and on those grey dark wintry days, sustainable lighting can be used.
Sustainable lighting normally consists of low voltage bulbs, led lamps etc. Solar power can also be used to drive lighting systems.
In passive houses, solar energy is maximised as much as possible on the surface of the house in winter. “Waste” heat from lighting and electrical appliances and body heat from inhabitants also add to the heat value of the house, but sometimes a heating top-up is still needed. That’s where space heating comes in.
Space heating can include a heating element incorporated into the ventilation system. This heating element could then be powered by solar thermal energy to make the house run 100% green, although there are other more traditional heating methods available such as gas or oil burners.
However, we feel using those burners would take away from the environmental benefits of having a passive house by introducing fossil fuel elements to what is essentially a clean build.
Passive houses are designed so that when the temperature outside the house is favourable, the air inside is exchanged with the outside. When the air outside is NOT at a favourable temperature, for example during wintertime, then a heat recovery ventilation system is used.
Interestingly, a feature of some modern passive houses nowadays is earth warming tubes. These tubes are buried in the garden and are used to preheat or precool air going into the ventilation system.
Regular double glazed windows won’t do for passive houses - in order to reduce heat loss in winter and heat gain in summer, windows need to be extremely well insulated. This normally translates to triple pane glazed windows with special coatings and gas between the different panes.
Are passive houses expensive?
You would think so, but actually bringing a building up to passive house standards, if done well and carefully, shouldn't mean the house is more expensive than a regular house. The reason for this is that the funding usually budgeted for installing a heating system can usually be used to bring about passive house modifications.
Traditionally, passive houses have been viewed as nice, but expensive, with estimates of their pricing at up to over 25% more expensive than a “normal” house. However jumps in technology and production over the last few decades, as well as clever cost-cutting - without cutting corners - have steadily driven down the difference to around 0%.
There is no consistent metric to measure pricing against, as passive house standards can differ from country to country and year to year. The easiest way to see if that new build you have your eye on could be made passive on the cheap is to analyse the following factors as extra costs:
- Extra components and materials (for insulation, windows, air ducts)
- Extra technology (solar panels, heat exchangers etc.)
Then check if you can take away these possible deductions from your building costs:
- Use single skin blockwork and external insulation instead of the usual masonry double skin.
- A standard heating system (small space heating units for passive house constructions typically cost far less than central heating systems).
There is also the fact that initial investment aside, the lifetime costs for maintaining a passive house, and a huge - or total- reduction in energy costs, represent some huge savings.
All things being equal, if you can keep the costs down for making a building passive house, then you’re definitely making a sound investment that will more than pay for itself in the long run.
In addition, there are several grants available for features of passive houses in Ireland. Finally, particularly for those who are buying to rent or investing in social housing, there is the fact that a passive house will enable your future tenants to avoid fuel poverty. An investment in a passive house building also future-proofs it against rising energy costs.
How are passive houses certified?
Under the Energy Performance of Buildings Directive from May 2010, all new builds must be “nearly” zero energy, or built to passive house standard, by 31st December 2020. With the deadline not far off, we think the EU may have been a bit ambitious with this target but we applaud the effort.
In Ireland, there is no “official” passive house certification body. There is, however, a passive house association of Ireland which organises training to ensure its members are au fait with the latest passive house standards. For this reason, if you’re looking into getting a passive house design, we suggest starting with their company members list.
The Royal Institute of the Architects of Ireland also provides a certified European passive house designer course for their members, accredited by the acclaimed Passivhaus Institut.
If you’d rather go your own route, just make sure to ask plenty of pertinent questions of the architectural firm you wish to contract. In particular, enquire as to which particular passive house standards they adhere to.
Who builds passive houses in Ireland?
There are several companies dedicated to building passive homes in Ireland.
Ecohouse has six beautiful designs ready, ranging from a tiny house to a contemporary two-storey, with an option to self build where they only provide you with the structure and plans, or a full build. A self-build will cost you €750 per m2, while a full build is €2000 per m2.
Viking house is a passive house construction company which specialises in timber builds and solar roofs.
Scandinavian homes, located in Galway, provide prefab low-energy and passive timber frame homes and operate all over the country. There are some very affordable options on their product listing, such as a 158m2 passive house from around €108,000.