Why Your EPC Still Penalises You for Night Storage Heaters

And What You Can Do About It

If you’ve recently received an EPC (Energy Performance Certificate) rating and were surprised to see your night storage heaters dragging down your score, you’re not alone. Thousands of UK property owners—especially in flats, rural homes, and electric-only dwellings—are discovering that these once-promoted systems are now a liability on paper.

So, why does your EPC still penalise you for night storage heaters, even if they’re working fine and using off-peak electricity?

Let’s break it down.

🔌 What Are Night Storage Heaters?

Night storage heaters are electric heaters that charge up overnight, using off-peak electricity (like Economy 7), and release heat during the day. They were widely installed from the 1970s to early 2000s as a cost-saving alternative in homes without gas supply.

⚙️ Why EPCs Penalise Storage Heaters

The EPC software used in the UK—RdSAP (Reduced Data Standard Assessment Procedure)—makes a few key assumptions:

1. Electricity is carbon-intensive.

While the grid is cleaner than it used to be, electricity still carries a higher carbon factor than mains gas in RdSAP. Even when used off-peak, electricity is assumed to have a larger environmental footprint.

2. Storage heaters are considered “less controllable.”

Compared to modern gas boilers or programmable electric radiators, most storage heaters:

• Don’t allow precise room-by-room control

• Lose unused heat in warmer weather

• Often require backup heating (e.g. fan or convector units)

This inefficiency is reflected in your EPC score—even if your bills are reasonable.

3. Lack of thermostatic and zoning features.

Unless you’ve installed smart controls or modern high-retention units, old-style storage heaters lack zoned heating and thermostatic controls, which are favourable EPC factors.

🔎 The Real-World Paradox: Low Bills, Low Score

It’s frustrating: your heating costs might be modest, but your EPC still rates you poorly. That’s because EPCs rate the fabric and fixed systems, not how you use them. So even responsible energy users with night storage heaters can get a D or E rating, or even fail rental compliance thresholds (currently minimum EPC band E, rising to C in the near future for landlords).

🛠 What You Can Do

✅ Upgrade to High-Retention Storage Heaters

Modern models store heat more efficiently, offer programmable controls, and may raise your rating if correctly documented. Look for heaters with:

• LOT 20 compliance

• Programmable timers

• Thermostats and temperature zoning

💡 Tip: Ask your EPC assessor to note full model details during the survey.

✅ Add Secondary Heating Controls

Supplementing with programmable thermostats, panel heaters, or underfloor systems can improve control—and your EPC.

✅ Insulate Well

Because electric heating is more penalised per unit of energy, improving insulation has an outsized impact. Consider:

• Loft and cavity wall insulation

• Floor insulation

• Draught-proofing

✅ Consider Switching to Renewable-Compatible Electric Heating

Systems like air source heat pumps or infrared panels are electric but treated more favourably under EPC due to their efficiency (SCOP rating) and lower carbon impact.

🏡 Selling or Renting a Property with Storage Heaters?

Before you panic about replacing the whole system, book an experienced EPC assessor who understands how to document modern features properly.

🔹 Book your EPC today
🔹 Explore our EPC services in London
🔹 Contact us for upgrade advice tailored to your property type

🔚 Summary

Don’t let outdated assumptions about your heating drag down your EPC.
With the right upgrades and assessor, even electric-only homes can achieve a high rating.