ᐅ Gas heating + solar thermal system

Created on: 10 Dec 2012 20:40
V
Vit84
Hello. A question for the experts and experienced home builders:

We are planning to build soon and already own a building plot. A natural gas line is available on the property. Since gas is quite expensive and alternatives are often considered... Is it sensible to combine a gas heating system with solar thermal for domestic hot water preparation? Or would it be better, considering current prices, to disregard gas heating and switch completely to, for example, a pellet heating system? It will be a single-family house. The exact heating demand is not yet known.

I would appreciate some basic information to understand the options better... I will consult professionals later but want to gather information through forums first... Many thanks in advance.
Vit8411 Dec 2012 14:08
Thank you for the active participation in this thread.

Although there is a natural gas line from the local supplier at the property boundary, and installing a gas heating system will likely be the cheapest option compared to others, we are still considering renewable fuels. We are relatively young and, God willing, will live in the house longer than the mentioned 20 years. No one can predict how gas prices will develop in the future. I also cannot say yet what our heating demand and behavior will be like. Of course, the choice of heating system depends on the construction method of the house. However, I want to start exploring various systems now and weigh their pros and cons.

I just wanted to know if it makes sense in principle to disregard the gas line and, for example, install a pellet heating system. PS: A basement will probably not be built, so we would rely on a pellet storage tank above ground. The question is whether this effort is worthwhile at all and, if so, how quickly the costs would pay off compared to a gas heating system...

This is a difficult question without knowing the details of the building project. Still, I would appreciate some hints, comments, etc....
€uro
11 Dec 2012 14:27
Vit84 schrieb:
Of course, the heating system installed depends on the construction method of the house. However, I would like to start exploring different systems now and weigh their pros and cons.
How could that be reliably possible if there are no demand figures available?
Vit84 schrieb:
... A difficult question when you don’t know the building project. Still, I would appreciate some pointers, comments, etc....
Exactly, guessing without a reliable basis. In my opinion, there is no sufficient foundation for a long-term investment decision.
Vit8411 Dec 2012 14:38
Thank you €uro, that was very helpful.
I want to gather information first and not make an immediate decision or investment.
B
Bauexperte
11 Dec 2012 14:46
Hello €uro,
€uro schrieb:

I see it differently ;-)
Of course 😉
€uro schrieb:

Well then, show us the results: investment cost (capital service for this) / actual yield. I’m curious ;-)
Posting all of that here would go beyond the scope of this forum, and the forum moderator would probably not be pleased. Please visit the Sonnenhaus Institute’s website; there you can find all the information—including the investment—on various new builds. I already contacted Professor Leukefeld today—I attended one of his lecture series last Wednesday—and requested the presentation slides. Once I have them, I will share the actual data.
€uro schrieb:

Completely wrong. The more thermal energy needs to be stored, the less economical it becomes!
That is your perspective, and I respect that.
€uro schrieb:

Gas condensing boiler plus connection costs are of the same order of magnitude compared to, for example, an air-source heat pump ;-)
I don’t disagree with that; however, the connection costs (after installation) tend to be significantly more favorable for solar thermal energy in the medium term.

Kind regards
€uro
11 Dec 2012 15:18
Bauexperte schrieb:
... Once I have them, I will provide the actual values.
I am looking forward to it.
Bauexperte schrieb:
... only the connection costs (after installation) will significantly favor solar thermal in the medium term compared to gas condensing boilers.
Well then, please support your claim with clear numbers and facts!
In the last case regarding the solar thermal system, neither you, your nationwide MEP planner, nor the original poster provided any clarification. In my assessment: pure "empty talk!"

Best regards.
B
Bauexperte
12 Dec 2012 12:53
Hello €uro,

“smart” as always ...
€uro schrieb:

I am eagerly looking forward to it.
I hope I remember. To help pass the time, I searched online for “builder feedback” on solar houses. I don’t want you to accuse me of manipulation – I don’t know the builders nor had any contact with the project; I removed the provider details because they are of secondary importance.

Front view facing south



Two-story building, 11.00 m (36 feet) wide and 9.50 m (31 feet) deep

“10.06.2008

Finally, we have decided to build a solar house.
We will have our house built entirely with ecological methods. This means the house operates without oil heating, gas, or heat pumps. It is a brick-built house with extra insulation on the exterior walls. Additionally, the house is oriented towards the south and features a large window front on that side. Also, we will have a water tank with a capacity of 7,000 liters (1,850 gallons) and about 4.60 m (15 feet) tall. This tank will be heated by solar collectors on the south-facing roof. If the solar cells do not provide enough heating power during the winter months, we will additionally heat with a wood gasifier stove. This stove has two advantages: it automatically includes a beautiful fireplace in the living room and uses about four cubic meters of wood (1 cubic meter equals 1 Ster) due to its special combustion process. The stove doesn’t just burn the wood but allows it to smolder, generating more kilowatt-hours than normal combustion. Moreover, the stove’s chimney is equipped with a heat exchanger to recover residual heat from the exhaust air.

18.08.08

Today, the energy savings certificate according to the German Energy Saving Ordinance arrived by mail.
The maximum allowable annual value according to the ordinance is 113 kWh/m².
The calculated value for our house is 9.48 kWh/m². Amazing!!! Fantastic.

17.11.2011

We have now been living in the house for three years, and (...) I want to mention one thing: our annual heating costs for hot water and heating are about 220 EUR. This means we need approximately 1.1 tons of wood per year to cover the days without enough sun. I am absolutely thrilled by this. Our electricity costs are also reasonable. Despite pumps and other systems, we have an average annual consumption of 2,900 kWh (three-person household, all employed). Really great!!!!”

I am confident that non-experts can place these freely accessible entries from the solar house construction diary into context.
€uro schrieb:

In the last case regarding the solar thermal system, neither you nor your nation-wide MEP engineer (...) contributed anything to clarify the situation. In my assessment: pure "empty talk!"
I have deliberately waited until today to respond; yesterday I probably wouldn’t have chosen my words so carefully.

It’s one thing to accuse me of “empty talk,” quite another to accuse a reputable partner. The MEP (mechanical, electrical, plumbing) design firm in question is not a small outfit that, due to price negotiations with potential clients, resorts to statements like “A good design/dimensioning is by the way very easy and inexpensive to get ;-) ” They exclusively offer integrated planning using simulation techniques to optimize energy use, overall technical planning that takes into account innovative, renewable, and alternative energy sources, etc. Their reference list is impressive, and they wouldn’t operate from five locations across Germany if they were “just selling empty talk.” So please restrict your sarcasm to me!

Finally, I could also overwhelm you with documents—similar to how you proceed here on the forum; whether this is productive remains to be seen. Recently, in response to a user asking “Since various vendors offer identical houses with different KfW values, there should be numbers on this. Too bad none of you knows them,” you replied, “I know them from individual construction projects. However, they are not generalizable.” Before this statement, you had offered your services, but you never considered publishing these values—even partially.

You know that I generally appreciate your responses here on the forum, but sometimes you too should wait a day before replying...

Best regards

Timber frame house under construction: Timber frame construction with scaffolding and construction surroundings