The tricky economics of greening your home
Published 31/05/2015 | 02:30
Buying and installing fancy renewable energy technologies like heat pumps, biomass boilers and solar panels should be well down the list of things you might do to improve your home's energy efficiency if you want to slash your heating bills, say architects and home-energy experts.
With over 40pc of consumers said to be planning home improvements this year, according to a recent survey for KBC Bank, a good portion of them are likely to involve improving roof or wall insulation, upgrading boilers, adding high-performance double or triple-glazed windows or installing solar thermal panels for water heating.
A good energy 'retrofit' will likely improve your property's BER rating and significantly reduce your heating bills.
The cost of these measures and a number of others can be mitigated if you apply for a grant under the long-running Better Energy scheme run by the SEAI (Sustainable Energy Authority of Ireland), especially since the Government upped their value by between 25pc and 50pc last March.
So you can get €300 towards the costs of insulating your attic, €700 towards the cost of a new oil or gas boiler (but only if you upgrade the heating controls too), up to €2,400 for internal wall insulation and up to €4,500 for external wall insulation. SEAI says each grant has been set to represent 30-35pc of the cost of each measure for the average home, with a payback period of roughly four to six years each.
Many households may apply for grants for more than one measure and, indeed, are encouraged to do so as the scheme will award a 'bonus' grant of an extra €300 if you undertake three measures, and a further €100 for a fourth measure.
But even with such support, the economics of greening up your home can fail if mistakes are made along the way, as often happens.
The first is to find yourself drawn to the 'eco-bling', the trendy renewable technologies, rather than focus on upgrading the fabric of the building first.
"Over the years, there have been a lot of low-energy new builds and retrofits, but we generally find that when consumers go to home-improvement shows, when they read the glossy magazines and start to research the whole area of low-energy, they are immediately drawn to the technology," said Archie O'Donnell, an architectural technologist and energy consultant.
Technologies like heat pumps and solar panels will provide little payback if the house itself is not well insulated to begin with, he said.
The second mistake is not to pay attention to the issue of ventilation and condensation.
"You have to think of retrofit like a stool with three legs," said O'Donnell. "We're very good in this country at addressing one leg, which is reducing energy in new builds and in a retrofit. What we're quite bad is the other two legs, which is moisture and ventilation."
Some types of dry lining, such as those that use thick composite plasterboards, can end up going mouldy behind the wall because, with the increased moisture, no thought has been given to improved ventilation. The ability of a house to overheat more rapidly also plays havoc with thermostats, O'Donnell added, making the heating system switch on and off constantly.
Bill Scott of Scott & MacNeil Architects says that external insulation can be a better investment in terms of payback than internal or cavity wall insulation.
"External wall insulation is probably much more efficient because it covers all of the junctions, it wraps the whole building like a tea cosy," he said. "It covers edges, junctions, between gaps and between panels and between materials where the insulation is effectively broken. It's expensive but it is good.
"It's not a replaceable item like a boiler that you expect to go after 12 years or so and then you upgrade it again. You should be getting a 30-year life span or more with external wall insulation because its part of the fabric of the house."
The same applies to renewable technologies. They have a place, he said, but they shouldn't be considered in isolation from other measures.
Indeed, one thing to bear in mind if you are undertaking more than one measure is that you may need to readjust your expectations regarding the heating cost savings. Each of the measures will do what they say on the tin in terms of a five-year payback or an eight-year payback, but if you combine measures, it won't create a multiplier effect, said Scott.
"If you undertake two or more measures, there's an interface between each of the measures, and they each diminish the value of the other."
Yes, agrees Tom Halpin, SEAI's head of information, but he adds that three typical measures that might each produce a 20-25pc energy cost saving on their own should still reduce the average heating bill by about half if done together.
SEAI-administered grants for installing renewable technologies, including heat pumps and biomass boilers, used to be available until 2011 but not anymore, says Halpin, because the aim of helping to build a credible market for home renewable technologies from what was a very low base has been largely achieved.
But there is still retrofit grant support for the installation of solar thermal panels for water and space heating of up to €1,200, albeit less than was available five years ago.
For some homeowners, particularly in rural areas, there may be a case for investing in 'microgenerators' that allow you to generate some of your own electricity, such as mini-wind turbines and solar photovoltaic (PV) panels.
It used to be possible for microgenerator users to sell any surplus electricity back to the grid for 9c per kWh, making the economics of the investment much more favourable, but the only electricity company to offer this export tariff, Electric Ireland, decided to abandon it last year.
In the absence of any export tariff, Quentin Gargan of Construction PV says his firm doesn't recommend solar PVs for retrofits, preferring to focus instead on new builds.
Prices for solar PV technologies have fallen in recent years, with one firm offering a 2Kw system fully installed for nearly €5,000.
In O'Donnell's experience, homeowners who invest in energy upgrades tend to do either a 'shallow' retrofit for under €10,000, which might involve a new boiler, roof insulation and dry lining some rooms, or a 'deep' retrofit in conjunction with an new extension or renovation, for which the budget might be up to €150,000.
There doesn't tend to be much in the middle ground, he says, such as a job involving a new heating system, external insulation and solar thermal panels for around €30,000.
But whatever you decide to do, the bottom line is to get independent advice and multiple quotes.
"What's most important to start with is that people, either from their own research and/or working with a reputable building contractor, BER assessor or an architect, actually assess their home rather than just the individual items that might be part of an upgrade," said Halpin.
Sunday Indo Business