How to improve your E2 rated home (it starts with the windows)

There is a specific feeling that every Irish person knows deep in their bone marrow. It is not the joy of a sunny day in July (which lasts approximately 14 minutes). It is not the taste of a decent pint. It is The Chill.

The Chill is not just “being cold.” Being cold is what happens when you forget your jacket. The Chill is different. The Chill is when you are sitting on your sofa, wearing two jumpers and a woolly hat, the heating has been on for three hours, and you can still feel the air moving around your ankles. You look at the thermostat. It says 21°C. You look at your hands. They are blue. You are experiencing the specific physical reality of living in a BER E2 rated home.

For decades, we have accepted this as a national quirk. “Ah sure, it’s an old house,” we say, as we watch the curtains sway in a room with no open windows. But today, we are going to stop accepting it. We are going to put on our lab coats (over our jumpers) and dive into the deep, dark, freezing cold ocean of Why Your House is Like This.

And it turns out, the villain of this story isn’t just the Irish weather. It’s a tiny, boring column in a spreadsheet called “Column AS.”

The E2 Eeyore: A Portrait of Sadness

If Irish houses were cartoon characters, the A-Rated new build would be Superman—strong, airtight, annoying. The E2 house is Eeyore. It’s trying its best, but it’s just fundamentally depressed. It leaks energy like a sieve leaks water.

According to the Sustainable Energy Authority of Ireland (SEAI), an E2-rated home consumes approximately 340 to 380 kWh per square metre per year. To put that in perspective, an A1 home uses less than 25. That means your E2 house is eating roughly 14 times more energy just to keep you barely alive.

But here’s the weird part. You might look at your house and think, “My walls are solid! My boiler works! Why is the rating so bad?”

The answer often lies in the “Single Glaze Survivor.” This is a specific type of house—usually built before 1980—that has managed to dodge every renovation trend of the last 40 years. It still has its original windows. And these windows are not just letting light in; they are actively murdering your thermal comfort.

The Villain Hiding in the Spreadsheet: Column AS

To understand why your house gets such a terrible score, we have to look at the brain of the operation: DEAP (Dwelling Energy Assessment Procedure). This is the software that calculates your BER. It’s basically a giant calculator that judges your life choices.

When an assessor visits your home, they look at your windows. If they see old timber sash windows or those silver aluminium frames from the 1970s, they have to input a specific variable into the software. In the data dictionary, this is often referred to as “Column AS” or the Percentage Draught Stripped.

This is where things get dramatic.

Imagine your house is a nightclub. The heat is the party inside. The windows are the bouncers.

• Modern Windows (100% Draught Stripped): These are terrifying, steroid-pumped bouncers. Nothing gets past them. The heat stays in the club.
• Old Windows (0% Draught Stripped): This bouncer is a skeleton. Or maybe he’s just asleep. Actually, he might not even be there. He’s left the door wide open and is currently texting his ex.

When the DEAP software sees “0% Draught Stripped,” it panics. It assumes that your windows are effectively open holes. It applies a massive penalty called the Infiltration Rate. It calculates that the air in your house is being replaced by outside air so fast that your heating system is basically trying to heat the entire county of Dublin.

This is why you can’t just turn up the thermostat. You are fighting a mathematical losing battle against the laws of physics and the Irish climate.

The Physics of “The Cold Wall” (Or: Why You Feel Like a Ghost is Hugging You)

Let’s get nerdy for a second. Why do you feel cold even when the air is warm? It’s because of something called Mean Radiant Temperature.

Your body is always radiating heat. If you stand next to a warm object, you feel cozy. If you stand next to a cold object—like a single pane of glass that is currently 4°C—your body rapidly radiates its heat towards that cold surface. It’s like the window is a vampire sucking the warmth out of your blood.

Engineers call this the “Cold Wall Effect.” You turn the air temperature up to 24°C to compensate, which costs a fortune, but you still feel a chill because half your body is radiating heat towards the window. This is the E2 Trap. You are paying for heat that you aren’t even enjoying.

And it’s not just about comfort. It’s about mould.

When warm, moist air hits that freezing cold glass, it condenses. Water runs down the pane. Eventually, black mould starts to grow. This is why the HSE lists damp and mould as major triggers for asthma. Your leaky windows are literally making you sick.

The Economic Horror Story

If the health stuff didn’t scare you, let’s talk about money. There is a new concept in the property market called the “Brown Discount.”

It used to be that buyers looked for location, location, location. Now, they look for BER, BER, BER. A report on Domestic Building Energy Ratings from the CSO highlights how newer, efficient homes are dominating the top ratings. Buyers are terrified of E2 homes. They know that buying one means signing up for a massive retrofit bill.

Conversely, moving from an E2 to a B2 can add significant value to your home—the “Green Premium.” It’s an investment that pays you back in two ways: lower bills every month, and a higher sale price when you eventually move to a villa in Spain (we can dream).

The “Window Trap”: A Policy Dilemma

So, you’re convinced. You want to fix the windows. You go to the SEAI website to look for a grant. And here is where you hit the “Window Trap.”

As of 2025, the SEAI grant structure is a bit tricky. You cannot simply get a standalone grant to swap your old windows for new ones. The government really, really wants you to do a “Deep Retrofit.” They want you to do the whole shebang: insulation, heat pump, windows, the works.

This makes sense on paper. Putting new windows in an uninsulated house is like putting a gold tooth in a shark’s mouth—it looks shiny, but the shark is still dangerous. If you seal up the windows but leave the walls uninsulated, you might actually make the mould problem worse because the moisture has nowhere to escape.

This is why you have to think about a “Whole Home” strategy. You might be obsessed with the windows, but often, the most cost-effective first step is actually external wall insulation Dublin homeowners have found to be transformative. By wrapping the house in a warm blanket first, you solve the “Cold Wall” effect on the masonry, which is often a bigger surface area than the glass.

The Tech: How to Beat the System

Okay, enough doom and gloom. How do we kill the E2 Eeyore and turn him into an A-Rated Superman? We need technology.

1. Vacuum Glazing (The Magic Trick)

If you live in a protected structure (like a Georgian house in Dublin 6), you can’t just slap in white plastic windows. The council will yell at you. Enter Vacuum Glazing.

This stuff is sorcery. It consists of two sheets of glass separated by a tiny vacuum gap (less than 1mm). Because heat cannot travel through a vacuum (physics!), it is incredibly insulating. It’s as thin as single glazing but performs like triple glazing. It’s expensive, but it allows you to keep your beautiful timber frames while telling “Column AS” to go take a hike.

2. Triple Glazing (The New Standard)

If you don’t have heritage restrictions, triple glazing is the way. It’s heavy, it’s thick, and it’s brilliant. The middle pane acts as an extra shield, and the gaps are filled with Argon or Krypton gas, which slows down heat transfer.

3. Demand Control Ventilation (The Lungs)

Remember the bouncer? If you install new windows, you are sealing the club shut. But people inside need to breathe. If you don’t provide ventilation, the air gets stale and damp.

Modern retrofits use “Demand Control Ventilation.” These are smart vents that sense humidity. If you have a shower or boil a kettle, the vent opens to let the moisture out. When the air is dry, it closes to keep the heat in. It’s like having a bouncer who is also a qualified HVAC engineer.

The Grid is Watching

It’s not just about your house anymore; it’s about the whole network. ESB Networks is currently rolling out the Smart Meter program across the country. Why? Because the future of the Irish grid is intermittent wind and solar.

An E2 house is a burden on the grid because it needs constant, high-grade energy to stay warm. An A-rated house is like a thermal battery. You can heat it up at 4 AM when wind energy is cheap and plentiful, and it will stay warm until evening.

This is why the “Single Glaze Survivor” is an endangered species. As we move towards dynamic electricity pricing, living in a leaky house is going to become financially unbearable. You will be paying peak prices to heat the garden.

The Future You

Imagine Future You. It is January 2026. It is raining sideways. A gale is blowing from the Atlantic.

Future You is sitting on the sofa. The thermostat is set to 19°C, but the room feels like 21°C. There is no draught at your ankles. The windows are silent. You are not wearing a hat indoors.

You check your phone. You made a few euros today selling excess power back to the grid from your solar panels. You smile.

This reality is possible. But it requires breaking up with your current windows. It requires ignoring the initial sticker shock and looking at the thermodynamic reality of your situation.

The “Single Glaze Survivor” had a good run. It saw us through the 70s and 80s. But it’s time to retire it. Your comfort, your health, and your wallet deserve better.

So, stop putting on another jumper. Start planning the intervention. If you are ready to stop heating the neighbourhood and start heating your home, take the first step today. Whether you need to wrap the walls or capture the sun, check out our solar options to see how a whole-home approach can change your life