What is the "Thermal Battery" effect and how does it apply to my floor heating?

Your home is already a battery, it stores heat instead of electricity. The concrete in your floors, the mass of your walls, and the water in your heating system all absorb and release thermal energy slowly. This is the "Thermal Battery" effect, and it's the single biggest reason Alva LINK can save you money without sacrificing comfort.

Here's the physics in simple terms. A well-insulated home with underfloor heating (hydronic) can be pre-heated by 1–2°C during cheap electricity hours and then coast for 3–6 hours without the heat pump running at all. You won't feel the difference: floor heating changes temperature so gradually that a 1°C swing over several hours is imperceptible. But the financial difference is significant, because you've shifted thousands of watts of consumption from expensive hours to cheap ones.

How Alva LINK uses your thermal battery

• ★It measures your home's thermal inertia. Over the first few weeks, Autopilot's thermal learning model maps exactly how your home behaves: how fast each room heats up, how fast it cools down, and how outdoor temperature affects the rate. Every home is different, and Alva learns yours specifically.
• ★It calculates safe pre-heating windows. If electricity drops to 0.10 kr/kWh at 03:00 and spikes to 1.50 kr/kWh at 08:00, Autopilot knows that heating your floor slab to 22.5°C by 07:00 means the house will still be 21.2°C at 11:00, well within your comfort range, even with the heat pump idling through the entire morning peak.
• It respects your limits. You set a minimum comfortable temperature (say 20°C). Autopilot never lets any room drop below that floor. It finds the cheapest way to maintain your preference, the path changes daily with prices and weather, but your comfort doesn't.

Why floor heating is especially well-suited: Concrete floor slabs have extremely high thermal mass. A 10 cm concrete floor can store roughly 30–50 kWh of thermal energy per 100 m² for every 1°C temperature increase. That's the equivalent of a small home battery — except it's already installed in your house and costs nothing extra. Radiator-heated homes have less thermal mass to work with, but Alva LINK still optimizes the timing of heat delivery to avoid peak prices.

Important: Alva LINK doesn't "overshoot" your temperature to dangerous or uncomfortable levels. The pre-heating is typically 0.5–2°C above your normal setpoint. The system is conservative by design, it prioritizes your comfort and adjusts its aggressiveness based on how your home actually responds, not theoretical calculations.