ᐅ Home Construction 2016 + Gas Heating

T21150 schrieb:
But it doesn’t make sense – as I said, it doesn’t contribute anything useful. It just costs money.

You can build things (including a photovoltaic system) that might cost more than they save, but at least they provide some benefit.

This ST zero-negative slider thing is slowly driving me crazy in my place here... just terrible nonsense.

Half of my utility room is taken up by a hot water storage tank big enough for half an indoor swimming pool. It was expensive. It takes up space. There are high losses due to its size (standby energy). The entire installation. The costs.

Honestly: I had to install it.

But when I see what the device actually delivers, it’s the worst bad investment I have ever made/had to make.

I also know other homeowners who have this nonsense on their roofs... all just as “enthusiastic” as I am. Some have it facing due south, I have it east-facing. But don’t believe it works that much better that way...

Well, at least you can enjoy a free warm shower on summer evenings when it’s 40°C (104°F).

Why didn’t you consider a controlled mechanical ventilation system, special electricity tariffs, additional insulation, or photovoltaic panels? We also have an east/west pitched roof – but I never wanted to put one of these ST systems on the roof. I kept the option open for better insulation as a backup plan.

merlin83 schrieb:
Well, at least in the height of summer, in the evening with 40°C (104°F), you can enjoy a free warm shower.

Why haven’t you considered controlled residential ventilation, special electricity tariffs, extra insulation, or photovoltaics? We also have an east/west gable roof – but I never wanted to install solar thermal on the roof. I kept the option of better insulation open just in case.

I have controlled residential ventilation with heat recovery. It works great – very satisfied, very useful.

The insulation is also very good. The house (KfW-70 certified) is close to KfW-55 standard, with an average annual gas cost of 40 Euros per month including hot water.

Next step would be additional insulation for the floor slab and more: 15–20K+ Euros, which was too expensive for me to save just 5 Euros per month.

I don’t need special electricity tariffs because I don’t operate a heat pump. My neighbor next door does, and he is proud of his low costs of only 70 Euros per month for electricity, which goes into the unit with a COP of 2.7. The house is about the same size in square meters—directly comparable.

I tend to shower warm (tepid in summer). But with the huge amounts of hot water available in good weather, I can’t use it all anyway. After about 5–6 days of a high-pressure system (Azores High—here in Velbert once every 5 years, haha), the storage tank reaches 74°C (165°F) – which at least saves me a thermal disinfection cycle. Luckily, I installed a mixing valve so we don’t get scalded by the overly hot water... so... I stick to my opinion: solar thermal here in this region is complete nonsense.

Photovoltaics were installed later on, since 04/07/16... also very satisfied. Much better than solar thermal.

Regards
Thorsten

T21150 schrieb:
I have a controlled residential ventilation system with heat recovery. It works great—very satisfied, very useful.

The insulation is also quite good. The house (KFW-70 certified) is close to KFW-55 standard, with an average gas cost of 40 euros per month for the whole year, including hot water.

The next step would be adding extra insulation under the slab and elsewhere, which would cost 15,000 to 20,000 euros or more. That was too expensive for me to save just about 5 euros per month.

I don’t need special electricity tariffs since I don’t use a heat pump. My neighbor next door does have one and is proud of his low electricity costs of just 70 euros/month, which runs the system with a COP of 2.7. His house is about the same size in square meters—fully comparable.

I usually shower warm (lukewarm in summer). But in good weather, the large amounts of hot water available just aren’t used up. After about 5 to 6 days of high pressure from the Azores (which here in Velbert happens maybe once in five years, haha), the water tank reaches 74°C (165°F). That at least saves me from having to do thermal disinfection. Luckily, I installed a mixing valve so we don’t burn ourselves with the overly hot water. So, I still maintain: solar thermal is pure nonsense around here.

The photovoltaic system was installed afterward on 07.04.16 and I’m also very satisfied. Much better than solar thermal.

Best regards
Thorsten

And who forced you to install solar thermal? The overall setup sounds quite realistic for the 2009 energy saving regulations—even without solar thermal.

merlin83 schrieb:
And who forced you to install the solar thermal system? Fundamentally, it all sounds very realistic for the 2009 Energy Saving Ordinance... even without solar thermal.

Purchased in 2013. Built in 2014.

2009 Energy Saving Ordinance.

The share of renewable energy required this strangely expensive, ineffective system. Yes.
According to the numbers, the house easily meets all requirements without any problem; it really didn’t need the solar thermal system. Even on paper, the controlled ventilation with heat recovery delivers significantly more, which is credible in practice. The solar thermal values—engineered and nicely calculated—are pure nonsense.

This could have been avoided with a heat pump.

But I didn’t want an air-to-water heat pump.

A ground-source heat pump: no deep drilling possible, no groundwater available. I would have had to install 350 m² (3,770 ft²) of loops in the garden (extremely expensive... generally so, but even more here: Bergisch slate... blasting, drilling, and going crazy... like many who built basements here with over 40,000 € extra costs and now regret it). So I didn’t want that either—it was too expensive. That’s why I chose a gas heating system, which then led to the solar thermal madness.

Best regards,
Thorsten

PS: That’s why I now recommend the new homeowner here in the forum to go for the air-to-water heat pump.

You save the gas connection (which was really cheap here in Velbert, only 4,500 euros minus a nice 1,000 euro discount in a special offer).

You save the capital costs for this full-scale solar thermal investment disaster.

Okay – air-to-water heat pumps cost more upfront than a gas condensing boiler (which are almost dirt cheap these days). I would have also needed to install underfloor heating… oh, that gets complicated… but it’s manageable. Whether I spend my 70 euros per month on gas plus capital costs or on air-to-water heat pump plus electricity costs: the money is gone either way…

In other words: hindsight is always 20/20. That’s why today I would (still gritting my teeth) choose the air-to-water heat pump, despite the need for underfloor heating.

Photovoltaics combined with an air-to-water heat pump at least provide pleasantly warm water from March to October, even when the sun isn’t shining directly… Photovoltaics make much more sense here than solar thermal systems in these latitudes.

Best regards
Thorsten

That is certainly frustrating. However, I don’t think this applies universally. For many other homebuilders (including ourselves), a gas condensing boiler combined with controlled ventilation of living spaces has worked well.