You’d nearly need a foreigner to visit to realise how cold your house is,” Dermot McElroy of Heat Pumps Ireland jokes when he learns I’m originally from Canada. “Or, you’d need to spend time in a colder country, where heating is more of a priority.” We’re talking about my early experiences in Ireland. I moved here in March 2013 – not the warmest time of year. In truth, during those first months in our draughty bungalow, I had never felt colder.

My husband and I are currently building a new home on the farm. During the design process, when asked what was on my wishlist, I only had two items: consistent heating and on-demand hot water. Luckily for me, new Irish builds are increasingly airtight; with better insulation and ventilation systems, making them comfortably warm when combined with an efficient heat source.

Heat pumps

Modern heating systems are moving away from fossil fuels – like oil and gas – and shifting to more sustainable methods. The heating systems currently available in Ireland fall under aerothermal and geothermal categories; aerothermal being more commonly known as air to water while geothermal is sometimes called ground heating.

Dermot and his team have been providing renewable heating sources to Irish homes for the past 15 years. He says things have changed considerably in this time.

“We started as a biomass heating supplier; specialising in biodiesel and wood pellet systems,” he says. “They were big, cumbersome devices, but they were the first main non-fossil fuel system to take hold here. Good ones were expensive and required a lot of maintenance. By chance, in 2005 we were at an exhibition and met some heat pump importers. I went to Sweden [where most heat pumps are designed], saw how they worked in cold weather, and knew this would be the way forward.”

Geothermal heating systems work by laying pipes underground. The pipes transfer geothermal energy and pump it into your home, providing consistent heating to the entire house. Aerothermal systems, by comparison, take energy from the air and pump it into your home.

Finding the right system

Dermot usually recommends geothermal heat pumps for new builds, especially those on farms, where there is space to lay the ground pipes. Air-to-water systems are also highly efficient and will work in conditions as cold as -20°C, while geothermal systems can go colder.

A geothermal system uses less visible equipment, most of it being underground. For air to water, there is a space requirement both inside and outside the house for necessary parts. Both systems provide consistent internal temperatures (hovering around 22°C) throughout the day and require minimal control. For new builds, both sources work best with an underfloor heating system.

“Underfloor heating is the only way to go,” Dermot says. “Put in a system where your heat’s coming from the floor and install ceramic or wood flooring, which are good conductors.”

Worthwhile retrofit?

Dermot always asks clients how much they use their current heating system and will usually recommend they stay with their boiler if heat isn’t used regularly throughout the day. Heat pumps offer significant payback in constant, steady heat and are worth the investment if you want your home to be a constant comfortable temperature.

Both systems cost over €10,000 to purchase and install; a geothermal system will cost €2,000 to €3,000 extra to lay the underground piping. This is a major cost in the beginning, but by using a heat pump, future oil or gas bills are eliminated. They are generally given a minimum five-year warranty, but Dermot says there is a big difference between warranty and life cycle.

“Air-to-water systems [have a lifespan of] 10 to 15 years, while geothermal systems last 25 to 30 years,” he says. “[These are new systems and many we’ve installed haven’t yet needed replacing]; I could better say [what reinstallation looks like] if you asked in five years’ time!”

Solar and PV Panels

There are two main types of solar energy available to Irish homeowners: solar PV, which produce electricity, and solar thermal, which provide hot water. Simon Whelan is a chartered energy manager and SEAI technical adviser with Glenergy Ltd in Co Wicklow. He says solar PV panels offer more of a return to the average homeowner.

“Solar thermal requires maintenance and the economic payback for them is a bit less than PV,” he says. “[PV panels] are put on the roof. They produce electricity; when light hits them they create an electrical current, which goes into an inverter. This changes the current into the type we use in our homes; that’s how it becomes usable electricity.”

“Thermal panels [literally get hot],” he continues. “You run water through them, the water gets hot and the heat is transferred into your hot water cylinder. They require a bit of maintenance and are a bit more expensive than PV systems. They’re not in favour as much now as they were five years ago.”

Cost considerations

An average solar PV system is priced at around €5,650 before any grants are applied, while a solar thermal system will cost the average household €1,000 to €2,000 more. They have a lifespan of over 20 years and there are grants available from the SEAI for homes built pre-2010. Even with the grants, they are a significant investment and, while Simon says most homes can expect a return on the cost within 10 years of use, there are still some issues to be resolved at a larger level.

“[With solar PV], something on in the house at that time, that electricity will go towards powering what’s on in the house,” he says. “If you’re out and there’s nothing on, the electricity is then fed to the national grid. There’s an issue there; you just lose that electricity, but with [the new] programme for government there’s a commitment to providing a payment for electricity that goes back into the grid.

“Depending on the price, that will make it more or less attractive to use PV,” he continues. “At the moment, we size systems for the amount of electricity being used in the house to try to limit that export and provide more value from the system. A 2kW system, which is seven to eight panels, is usually best for most Irish households. You can also heat water with excess PV by inputting a system which sends it to your hot water cylinder.”

Home heating at a glance

1 If your home isn’t yet well-insulated or airtight, it makes sense to address those issues before considering the purchase of a new heating system.

2 If retrofitting, an air to water system is usually the better system to go with, but you need to find adequate space (both indoor and outdoor) for the units.

3 For new builds (especially those in rural areas), geothermal heat pumps are slightly more expensive but have a longer life span and work well even in the coldest conditions – they also have less of a space requirement as it’s mostly underground.

4 Solar thermal panels provide hot water and, in homes built pre-2010, can be purchased with the aid of an SEAI grant. Solar PV panels provide electricity but can also be used to heat water.

Ask a contractor

David O’Dwyer operates Cooldine Construction Ltd in Horse and Jockey, Co Tipperary. He says the company’s clients mostly decide on air-to-water heat pumps as they’re seen as the most cost-effective and efficient system to install.

“The one issue we have with modern heat pumps is the size of the unit. It’s the same size as a tall fridge, so you need a dedicated place for it. You need at least two linear metres of wall space (floor to ceiling) to contain everything.

“The outdoor fan unit [for air to water] is two thirds the size of the indoor unit,” he continues. “Before you start building block work, you should know where the units are going so you can allow for laying any connecting pipework. All new houses should really have a dedicated plant room for the indoor heat pump, water storage, water softener system, fuse board and control panels. If you don’t have a plant room, you should aim to have it all in the one area for maintenance purposes.

“The days of the old immersion are gone, The heat pump will provide all your domestic hot water needs as well as space heating.

“You can use this system with new aluminium radiators – although it’s a little less efficient. In the case of retrofits; just changing the rads might not be enough, the pipework may need to be changed, as well,” he says. “If you’re taking up the floors to change the pipework, it’s extra but worth it to dig up the floor and just lay the piping to do underfloor heating.”