Maximising Your Home Retrofit: Insulation, Ventilation & Airtightness
In the fifth and final part of Quote Devil’s home retrofitting series, we’ve teamed up with heating and renewable energy product supplier, Precision Heating from Dublin.
We’ve covered retrofitting from every angle—how to tell if your home needs an energy upgrade, shallow vs. deep retrofits, solar power and heat pumps. So, it’s time to seal the deal (literally) with an important but often overlooked area: insulation, ventilation and airtightness.
A well-insulated, airtight home is warmer in winter, cooler in summer and cheaper to run. But what’s the best way to achieve that balance? And how do airtightness and insulation impact your home’s overall energy performance? Let's break it down, including some useful advice from Yasmin Beharic, Precision Heating’s Marketing Manager.
Internal vs. external insulation—which one’s for you?
If your home is losing heat, insulation is the first line of defense. But should you insulate internally or externally?
External tends to be the first choice for most as it doesn’t interrupt your home life. But for heritage properties or where outside insulation is impossible, internal wall dry lining is the next best option. As Yasmin points out, each comes with pros and cons:
“Choosing between internal and external wall insulation comes down to a few key things. First off, external insulation costs you more. Then, if you go internal, just keep in mind you'll lose a little bit of room space inside. Also, internal insulation means redecorating the whole house, which can be a bit of a hassle.
Finally, external insulation will definitely change the appearance of your home from the outside, which could be a positive or negative depending on your personal taste.”
Fortunately, all homeowners (even private landlords) can apply for an SEAI insulation grant to help meet costs as long as their homes were built and occupied before 2011. How much you can access depends on the insulation method and type of property:
● Attic insulation—up to €1,500
● Cavity wall insulation—up to €1,700
● Floor insulation—up to €3,500
● Internal wall insulation (dry lining)—€3,500 for a semi-detached and €4,500 for a detached home
● External wall insulation (full wrap)—€6,000 for a semi-detached and €8,000 for a detached home
For many, budget and disruption are the biggest deciding factors. If you’re living in the house during the work, internal insulation means dust, plastering and a temporary mess—but if you’re already planning a renovation, it could be a smart add-on.
On the other hand, external insulation is costlier upfront but has the advantage of wrapping your home in a thermal jacket without disrupting your interiors.
Either way, the goal is the same: locking in heat, saving money and making your home more comfortable year-round.
Airtightness—why it matters
Insulation is only half the battle. If your home isn’t airtight, heat will still escape and you’ll pay the price in higher bills.
“It’s important to have a blower door test carried out to show the infiltration rate of the property and identify where the heat is escaping. Once we know where the airtightness needs improvement, we can carry out the appropriate airtightness measures.”
These measures typically involve sealing windows and doors, addressing attic and basement leaks and ensuring proper sealing of plumbing and electrical penetrations.
In other words, close the gaps before cranking up the heat! Proper airtightness means fewer draughts, lower heating costs and a home that stays warm without making your heating system work overtime.
How insulation & airtightness improve heat pump performance
If you read our last article, you’ll know heat pumps are one of the best energy-efficient heating solutions around. But here’s something many people don’t realise—if your home isn’t insulated enough, your heat pump will have to work harder.
“Minimising heat loss by upgrading insulation reduces the size of the heat pump needed to heat your home,” adds Yasmin. In turn this means less energy waste, and lower running costs“
So, if you’re planning to install a heat pump, make insulation your first priority—otherwise, you’ll be heating a house that’s still leaking warmth like a sieve.
What about ventilation? Won’t my house be too stuffy?
Airtightness is key, but your home still needs fresh air. The solution? Good ventilation.
A common mistake to make is sealing up every gap without thinking about airflow, which leads to condensation, dampness and poor indoor air quality.
That’s why many modern retrofits include mechanical ventilation systems that bring in fresh air without losing heat. Think of it like a controlled airflow system—keeping your home energy-efficient but with room to breathe.
Check your home insurance
Like any major home upgrade, insulation and airtightness can impact your home insurance. The good news? A well-insulated, airtight home is generally lower risk—less chance of burst pipes in winter, less mould and damp issues and fewer heating-related hazards.
But here’s the thing—you need to let your insurer know. Any major retrofit work could affect your policy, so it’s worth checking that your cover reflects your home’s new and improved energy rating.
Final thoughts
If you’re investing in a retrofit, insulation and airtightness are two of the smartest upgrades you can make. Paired with better ventilation, your home will stay warm, efficient and healthy. All of which means:
✅ Lower energy bills ✅ More comfort year-round ✅ A better-performing heat pump ✅ Less risk of damp, mould and heat loss
And that’s a wrap—the final chapter in our home retrofitting series. We hope our tips from some of Ireland’s top One Stop Shop providers have given you a solid understanding of how to upgrade your home, cut energy costs and make the most of government grants.
Don’t forget to make sure your home insurance is upgraded too. Quote Devil can get you a great deal in minutes, whatever retrofit you’re planning.
We compare quotes from Ireland’s leading insurers and if you buy online, we’ll give you a €65 discount.
