by Alissa MacMillan
Q: As it’s getting cooler out, I’m starting to think about how well my house is insulated and if I should make changes before winter. Any suggestions?
A: Indeed, with better insulation, you’ll use a lot less energy, which is good for the earth and your wallet. Joseph Little, Head of Building Performance and Construction in the School of Architecture, Building and Environment at TU Dublin, explains that the most obvious, easiest, and effective area to tackle is the attic. He can’t tell you how many times he’s been up to an attic where he’ll find no insulation or “bits done, with two or three rolls sitting there which have never been unrolled.”
It might seem like the attic’s primary role in life is for storing Christmas decorations, but not so. The main function is “to create structure to support slates that take water off the building, so to manage moisture,” and, secondly, for “thermal continuity” or “its ability to have a thermal line,” which keeps the heat in. Third, you can store stuff, so don’t let the tertiary function take primacy, he warns.
If there’s no insulation, it’s “probably the biggest area you’re losing heat from,” Little says. The good news is, “the quickest and cheapest insulation you’ll ever buy is for thermal comfort in the attic.”
When insulating, he encourages opting for quality, for example, a biomaterial like Isover Matec quilt insulation, as the cheaper products can collapse quickly, “make you itch,” and “spray insulation is nasty stuff.” 250mm-300mm is just the right amount and he recommends Metac or Earthwool insulation, both mineral wools, spun into fibres, and made into a quilt. It comes in a long roll and can be layered in between joints in the attic and then layered across, tightly fitted in.
Wood fibre insulation or sheep’s wool are also good bets, he says, as is post-consumer paper cellulose, which is the cheapest bio-based option. It’s on par with others for thermal management and is especially good for moisture management. If you want to stay truly local, Ecocel, an insulation made in Cork, uses waste material from old editions of the Irish Examiner, The Avondhu, etc.
AIR PRESSURE TEST
You’ll need to clean out the attic space well and wear basic masks and gloves. “Please empty everything out of the attic, take the hoover, clear the thing, clean the thing, do it systematically.” If you don’t, it can “create compromises all over the place, then it’s a botched job from the beginning.”
Little’s next suggestion is checking your home for airtightness or “identifying and removing the gaps and cracks you didn’t even know were there.”
When it comes to airtightness, “you can do a lot yourself,” he notes. There are registered air pressure testers in Cork who can measure the overall impact of unintended gaps and cracks in a standardised way and compare it to the national standard. Even better, Little recommends a “diagnostic” air pressure test “where someone walks with you around the house and measures air leakage at windows, doors, feel gaps and cracks,” and this will give you precise information on where air loss is coming from and how much proportionately. Vane-type anemometers are generally used with a digital output (in metres/second), but your hands or even eyelashes can also be very good detection devices.
A diagnostic air pressure test will take about two hours, you’ll get a 10 page report, “giving you objective scientific data.” It would cost around €350 but gives you objective information that can allow proper planning and support a phased approach to the retrofit works you might want to do. “There is no point putting in insulation if air movement whips past it, taking away your expensively warmed air,” he says. If you insulate, turn your heating system off, and the house gets cold, “the problem is not insulation,” he explains, “it’s about airtightness.”
VENTILATION
As your home becomes more airtight, it becomes ever more important to have a properly sized, installed and verified ventilation system, Little explains. While “holes in the wall,” a rarely-used cooker extract hood, or a weak, intermittent fan in the bathroom might be the usual systems, these are “utterly inadequate,” he says. Little recommends systems like demand control mechanical extract ventilation (DC-MEV) and the more expensive and complex mechanical extraction with heat recovery systems (MVHR), which you can find from Aereco, Lunos and ProAir.
Even if it’s airtight, you can open the windows, although with a good mechanical ventilation system, you may feel less need to do so. “Just like our bodies need to be able to breath and sweat, we want a building to be breathable,” he says, “we want comfort, health, enjoyment, and delight.”
Tiny changes can also go a long way. For example, look at your attic hatch. “Is it a loose piece of plywood or does it have a bolt with a compression seal that would give airtightness,” keeping warm air, which rises and carries moisture, from flowing out. “You can spend two euros to buy those seals.” All bigger and smaller adjustments for a warmer, drier, more eco-friendly autumn and winter.
