Your Guide to Passive Houses in Ireland

Published on 30 September 2020

One-quarter of the energy produced in Ireland is consumed by homes, which are also responsible for one-quarter of all CO2 emissions, according to data from the Sustainable Energy Authority of Ireland (SEAI). Passive houses aim to reverse this trend by providing more comfortable living spaces that also have a lower impact on the environment.

What is a passive house?

A passive house, a term derived from the German word Passivhaus, is designed to minimise energy consumption by maintaining a comfortable temperature during winter and summer, in addition to providing good air quality.

These houses are built to very rigorous standards involving a high degree of insulation without thermal bridges, along with super-efficient heat recovery and ventilation systems and strictly controlled rates of air infiltration.

The climatic and geographical conditions of each site are also taken into account to make better use of solar and wind energies, all with the aim of reducing the building’s carbon footprint.

The advantages of a passive house

A passive house isn’t only beneficial for the environment as it also offers its owners numerous advantages. Above all, owning such a home lowers energy bills while still allowing you to enjoy cosy spaces without drafts or cold spots in the winter, along with cooler rooms in summer.

With less technology that can fail, these homes also tend to have lower maintenance costs. Another point in their favour is that the indoor air is cleaner inside a passive house, which has a positive impact on the health of those who live in them.

Technical standards a passive house needs

  • The building’s heating and cooling demand must not exceed 15 kW/h per square metre. This means that a 100 square metre house should not exceed consuming 1,500 kW/h per year. This is a very low figure if you consider that an Irish home consumes an average of 11,150 kW/h in heating, according to a report by the Commission for Energy Regulation.
  • Total energy consumption, including electricity and hot water production, must not exceed 60 kw/h per square metre per year. In a 100 square metre house, this would imply a consumption of only 6,000 kW/h, while the national average is 14,650 kW/h per year.
  • The air cannot leak out of the building at more than 0.6 air changes/hour at 50 Pa of pressure. This represents a high degree of airtightness, since the values of “normal” homes can range from between 5 and 7 in the best of cases, with older houses reaching 10 air changes/hour. During construction, several Blower Door tests are usually carried out to verify that everything is working correctly.
  • There should be adequate thermal comfort in all living areas, both in the summer and in the winter, with less than 10% of the hours in a given year over 25ºC.

It's worth clarifying that passive houses are characterised by their superinsulation, a way of building that produces levels of insulation and air-tightness that are higher than usual. In fact, these buildings have special windows that allow them to retain as much heat as possible. They have triple glazing and two chambers optimised with gases such as argon or krypton and include sun protection, depending on the direction they face. In addition, the frame has at least three gaskets to prevent air permeability.

It’s also important to note that although the aim of a passive house is to do away with regular heating systems, an alternative heating system is often required in Ireland as a supplement to increase the temperature on colder days.

However, since passive houses have a low heat demand, much of their energy is used to produce hot water. So, installing an efficient hot water system and using solar thermal collectors will reduce energy costs and their ecological footprint.

Of course, natural light is also maximised in passive houses to reduce the amount of energy used for lighting. They opt for sustainable and low-consumption lighting such as LED lamps, although solar panels are also used to power the lighting system.

Is it expensive to build a passive house?

Many people think that building or retrofitting a home to adapt to passive house standards is expensive, but this isn't actually the case. In the past, a passive house could be up to 25% more expensive than a “normal” house, but advances in technology and production of more efficient and sustainable systems have lowered their cost, and the current cost is only 10-15% more than building a typical house.

In addition, the savings in energy costs and maintenance make up that difference in just a few years. The high energy efficiency of a passive house increases its market value, making it a solid investment that pays for itself quickly. Also, there are grants for building more energy efficient houses available in Ireland.


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