Why Is My Gas Bill So High? Hidden Costs of Vloerverwarming (Underfloor Heating) in Renovated Homes

You’ve moved into a freshly renovated Dutch home, complete with sleek vloerverwarming (underfloor heating) and modern finishes. The thermostat sits at a modest 16°C, yet your gas meter spins like a Dutch windmill in a January storm. Sound familiar? You’re not alone. Young households across the Netherlands are discovering that “renovated” doesn’t automatically mean “efficient”, especially when it comes to gas consumption in homes with vloerverwarming.

The Zwolle Shock: 15 Cubic Meters Per Day at 16°C

A recent case from Zwolle perfectly illustrates this growing problem. Two siblings, aged 26 and 24, moved into a 90m² renovated property with vloerverwarming underneath 8mm laminaat (laminate flooring). With the thermostat locked at 16°C and only one person actually living there, they were burning through 15 cubic meters of gas daily. For context, the average Dutch household consumes about 1,169 m³ per year, this single occupant was on track to use nearly 5,500 m³ annually.

At current gas prices of €1.331 per m³ (including taxes and levies), that’s €20 per day, €600 per month, just for heating. The math is brutal: 15 m³ × €1.331 = €19.97 daily. Multiply by 30 days and you’re looking at nearly €600 disappearing from your bank account while you shiver in what should be a frugal 16°C.

Why Underfloor Heating Isn’t Always Efficient

Vloerverwarming promises luxurious, even warmth at lower temperatures. The theory is sound: heating from the floor up allows you to feel comfortable at 18°C instead of 20°C. But theory and Dutch renovation reality often diverge dramatically.

The Flooring Material Trap

Here’s where many renovators cut corners that cost you thousands. Standard laminaat (laminate) and even some tile installations create an insulating barrier between your heating pipes and the room. As one technical expert noted, you need flooring with extremely low thermal resistance (R-value) for efficient vloerverwarming operation.

The Zwolle case featured 8mm laminaat, likely installed without proper underfloor insulation boards. This means your boiler works overtime heating not just the room, but also the concrete subfloor and the flooring material itself. It’s like trying to warm your house through a thick winter coat, the heat reaches you eventually, but most energy dissipates elsewhere.

The OpenTherm Paradox

OpenTherm is a communication protocol that allows your thermostaat (thermostat) and cv-ketel to speak the same digital language. Instead of simple “on/off” commands, OpenTherm enables continuous modulation, your boiler can run at 30% capacity instead of blasting at 100% then shutting down completely.

In theory, this saves 10-20% on gas consumption. In practice with vloerverwarming, it can backfire spectacularly. Underfloor systems are slow, changes in water temperature take hours to affect room temperature. OpenTherm’s sophisticated algorithms, designed for responsive radiator systems, often misread this delay. The protocol anticipates room temperature changes that haven’t happened yet, causing your boiler to cycle erratically and waste gas on unnecessary pre-heating.

Worse, many Dutch homes have mismatched equipment. Your fancy new smart thermostaat might speak OpenTherm, but your Vaillant or Nefit boiler from 2015 might only understand proprietary protocols like eBus or EMS. Without a proper converter module, you’re stuck in inefficient on/off mode, or worse, the system defaults to maximum output “just to be safe.”

The Real Cost: Doing the Math

Let’s put this in perspective with actual Dutch energy pricing data. The average variable gas tariff currently sits at €1.331 per m³, but this figure masks the true cost structure:

• Base price per m³: ~€0.60-€0.65
• Energy tax (Energiebelasting): €0.7267 per m³
• Transport and fixed fees: €247.55 annually
• Supplier margin: Variable

For the Zwolle household consuming 15 m³ daily, the annual breakdown looks like this:
– Consumption: 5,475 m³
– Energy tax alone: €3,979
– Base cost: ~€3,285
– Total estimated annual gas bill: Over €7,500

Compare this to the average Dutch household: 1,169 m³ costing approximately €1,555 annually. The “renovated” home was set to cost five times more than average.

Practical Fixes: What You Can Actually Do

1. Check Your Floor Build-Up

Verify whether your flooring is actually suitable for vloerverwarming. Look for certifications or documentation from the renovator. If you have standard laminaat without proper heat-conductive underlayment, you’re fighting physics. The solution isn’t cheap, replacing flooring costs €30-50 per m², but it pays for itself in 2-3 winters.

2. Audit Your Boiler Settings

Check your ketel pressure (should be 1.5-2.0 bar) and bleed your vloerverwarming system. Airlocks in the pipes can reduce efficiency by 30-40%. Many systems also have a maximum water temperature setting, for vloerverwarming, this should be 35-45°C, not the 70-80°C used for radiators.

3. Evaluate OpenTherm Compatibility

Use the Duurzamerhand compatibility checker to see if your thermostaat and ketel can communicate via OpenTherm. If not, a €50-150 converter module (like the Vaillant VR33) might unlock 15% savings. But remember: for vloerverwarming, sometimes a simple on/off thermostaat actually works better than a “smart” system.

4. Inspect Insulation

This is the uncomfortable truth: many Dutch “renovations” are cosmetic. Lift a floorboard (if possible) and check for edge insulation around the vloerverwarming perimeter. Without it, you’re heating the ground beneath your house and the walls, pure waste.

5. Compare Energy Contracts

Your high consumption amplifies the impact of your per-m³ rate. At 5,000+ m³ annually, even a €0.05 difference between suppliers saves €250. Use comparison tools to find the best rate, but be wary of “teaser” tariffs that spike after the first year.

When “Renovated” Doesn’t Mean “Efficient”

The uncomfortable reality is that Dutch housing renovations often prioritize aesthetics over energy performance. A fresh coat of paint, new keuken (kitchen), and vloerverwarming installed by the cheapest contractor create the illusion of modern efficiency while hiding fundamental flaws.

The CBS data shows average gas consumption has been declining nationally, but this masks a growing divide: properly renovated homes consume 30-40% less than average, while botched jobs can use 200-300% more. Your high bill isn’t a personal failure, it’s likely a systemic issue with how the renovation was executed.

Before you accept €600 monthly gas bills as your new normal, treat your heating system like a crime scene. Document everything, check each component, and remember: in the Netherlands, the most expensive heating system is the one that was installed incorrectly.