Underfloor heating air-water heat pump. House too warm when the sun shines

Hello everyone,

I have a general question.

We moved into our new house four months ago. The living area on the ground floor has three large floor-to-ceiling windows facing the south side. We have underfloor heating and an air-to-water heat pump. It creates a really pleasant temperature in the house, but we have a problem – as soon as the sun shines outside in winter, even when it’s -2°, we suddenly have 24° in the living room. It gets incredibly warm in here, and you can’t just quickly turn down the underfloor heating. Do you have to assume that the large floor-to-ceiling windows are responsible for the heat? A picture of the south side of the house is attached. What would you do, always lower all the blinds as soon as sun is forecast? That’s kind of annoying too... We have roller blinds from Somfy. Would you buy the sensor that automatically lowers the blinds at a certain temperature? Thanks in advance for your answers

Venetian blinds instead of roller shutters. Automation is also a good idea Yes, the sun is to blame. The poor underfloor heating is not at fault.

as soon as the sun shines outside in winter, even if it is -2°, we suddenly have 24° in the living room. it gets incredibly warm in here, you can't just quickly turn down the underfloor heating.

Just wait for summer then The blame lies solely with the windows and good insulation of today's houses. It is independent of the heating. Currently, you not only have to take care of your heating system but also plan for efficient shading (which is actually schizophrenic). Guckuck2 has already said something about that. An air conditioner can also help in summer.

Do you have to assume that the floor-to-ceiling large windows are responsible for the heat?

I can confirm that as well. It's the same with us.

What would you do, always lower all the shutters as soon as sun is forecasted?

Nothing at all. Apart from the fact that the shutters were already purchased for sun protection (which was mandatory for us), we enjoy the warmth and the rays for which the sun is responsible. We built these windows on the south side for exactly that reason.

If it gets too warm in winter, automated shading is especially appropriate in summer. Venetian blinds would of course be more comfortable. In winter, I would work with a sensor for sunlight or temperature, in summer I find time control more comfortable so that the shading doesn't move up and down constantly.

Try if it is enough to shade a maximum of 1-2 windows in winter in the sun, then you still have light and do not completely block the sun for heating support. Room temperature generally 1 degree lower and the house can absorb more heat without possibly becoming too warm.

Unfortunately, we only have one such south-facing window in the living area. It only gets too warm from mid-September on during peak weather over several days and not at all in October.

Make sure that the underfloor heating generally runs at the lowest possible temperature. That is more effective than a possibly existing thermostat because the underfloor heating then physically can no longer heat the room further when there is sun.

If necessary, consider heat protection coating as a foil. Perhaps more sensible than blocking out the sun in winter and also useful in summer.

Window open. It’s sometimes quite nice - even in winter