Good evening everyone,
My wife and I are looking for a concept for the future energy supply of an old farmhouse. I hope this category is the right one; if not, please move it.
General: The farmstead is in a remote location, with the nearest houses about 500 meters (550 yards) away. The farmhouse will have approximately 300 sqm (3,230 sq ft) of living space in the future (possibly more) and is connected to the public electricity grid and sewer system. Heating and hot water are currently provided by a gas instant water heater (gas supplied from a liquefied petroleum gas tank). We plan to renovate the farmhouse extensively. The walls are half-timbered construction (straw and clay) and will be rebuilt. As part of this renovation and conversion, all electric and plumbing installations will be replaced. We are now considering how to plan the future energy concept for the house.
A few facts about the conditions:
For the renovation, we are now considering how we want to provide heating and hot water in the future. Additionally, we are thinking about generating electricity with a photovoltaic system for self-consumption and feed-in.
Some ideas we have considered include:
Basically, we are open to all ideas but tend toward renewable energy sources (as long as they are reasonably economically viable).
From the experts’ point of view, what makes the most sense here?
My wife and I are looking for a concept for the future energy supply of an old farmhouse. I hope this category is the right one; if not, please move it.
General: The farmstead is in a remote location, with the nearest houses about 500 meters (550 yards) away. The farmhouse will have approximately 300 sqm (3,230 sq ft) of living space in the future (possibly more) and is connected to the public electricity grid and sewer system. Heating and hot water are currently provided by a gas instant water heater (gas supplied from a liquefied petroleum gas tank). We plan to renovate the farmhouse extensively. The walls are half-timbered construction (straw and clay) and will be rebuilt. As part of this renovation and conversion, all electric and plumbing installations will be replaced. We are now considering how to plan the future energy concept for the house.
A few facts about the conditions:
- Next to the farmhouse is a barn facing south-southeast (about 25-30 m (80-100 ft) away). The roof has an available area of approximately 80 sqm (860 sq ft). The roof was replaced about 10 years ago.
- The farmhouse roof is about 25 years old. Currently, there are no plans to replace this roof. The question here is how sensible it is to install a photovoltaic system or solar thermal system if the roof will need to be renewed in about 20 years. There is space for about 60-70 sqm (650-750 sq ft). The orientation is southwest.
- There is plenty of space around the farmhouse. For energy systems that require a lot of space, there is enough room—though a wind turbine is not an option.
- One side of the farmhouse borders a forest. This forest belongs to the farm and could provide wood “free of charge.”
For the renovation, we are now considering how we want to provide heating and hot water in the future. Additionally, we are thinking about generating electricity with a photovoltaic system for self-consumption and feed-in.
Some ideas we have considered include:
- Building a large enough masonry stove to heat large areas of the house.
- Solar thermal system for hot water generation (only makes sense on the main house—or can hot water be channeled underground to the main house?).
- Photovoltaic system for electricity (possibly with storage?)—this could be significantly oversized for grid feed-in.
Basically, we are open to all ideas but tend toward renewable energy sources (as long as they are reasonably economically viable).
From the experts’ point of view, what makes the most sense here?
H
hampshire27 Dec 2019 12:25Very interesting project!
Renewable energy for an old house. You will need somewhat more energy per square meter than our airtight new builds – so efficiency considerations that affect running costs become particularly noticeable.
My thoughts on this:
Photovoltaics are always worthwhile on an unshaded roof facing southwest in the Essen area. You could also consider including some east-facing panels; although they are less efficient per square meter on paper, if you want to cover the base load of the house with your own power for a few more hours, you might gain a few extra hours when you don’t need to buy expensive electricity. If you like, I can connect you with a friend who is currently working on a prominent photovoltaic project in Essen and can provide you with a reliable yield calculation.
Heat pumps combined with underfloor heating are efficient heating systems – since you have plenty of space and probably no solid rock beneath, I recommend you look into ice storage heating systems. These are worthwhile only with higher energy demands – which you have due to the large and older buildings. The principle is simple and extremely environmentally friendly: energy is stored in a concrete tank underground, filled with water, and extracted there by a heat pump through refrigerant pipes. The clever part is the use of crystallization energy released when water freezes. The ground supplies the water tank with heat energy through its stable temperature, “warming” the water back up against the energy extraction.
Why?
In my view, this system offers the advantages of constant geothermal heat without affecting the temperature conditions of microorganisms deep underground, which are important for good soil and water quality. At the same time, the heat pump can be set very efficiently (due to constant conditions) and does not suffer the winter efficiency losses typical of systems that extract energy from the air.
Disadvantage: there are still relatively few installed systems on the market, and many installers and consultants have a “don’t know it, don’t build it” mentality.
The masonry heater has an incredible appeal to many people (including us) because of its very pleasant radiant heat. Since you don’t want to use wood continuously, I would install this as a “luxury” secondary system. You really need to be passionate about handling firewood to rely exclusively on such a system.
Our neighbors use a wood log gasification boiler for heating. These are now also available with automatic fuel feeding. I have no idea how reliable that is. This makes refueling easier, but the challenge of cutting or sourcing wood obviously remains.
Please keep in mind that these are just suggestions to encourage you to think outside the box – like many others here, I am not a professional. Most people here work with systems for new buildings, where the calculations are different.
Renewable energy for an old house. You will need somewhat more energy per square meter than our airtight new builds – so efficiency considerations that affect running costs become particularly noticeable.
My thoughts on this:
Photovoltaics are always worthwhile on an unshaded roof facing southwest in the Essen area. You could also consider including some east-facing panels; although they are less efficient per square meter on paper, if you want to cover the base load of the house with your own power for a few more hours, you might gain a few extra hours when you don’t need to buy expensive electricity. If you like, I can connect you with a friend who is currently working on a prominent photovoltaic project in Essen and can provide you with a reliable yield calculation.
Heat pumps combined with underfloor heating are efficient heating systems – since you have plenty of space and probably no solid rock beneath, I recommend you look into ice storage heating systems. These are worthwhile only with higher energy demands – which you have due to the large and older buildings. The principle is simple and extremely environmentally friendly: energy is stored in a concrete tank underground, filled with water, and extracted there by a heat pump through refrigerant pipes. The clever part is the use of crystallization energy released when water freezes. The ground supplies the water tank with heat energy through its stable temperature, “warming” the water back up against the energy extraction.
Why?
In my view, this system offers the advantages of constant geothermal heat without affecting the temperature conditions of microorganisms deep underground, which are important for good soil and water quality. At the same time, the heat pump can be set very efficiently (due to constant conditions) and does not suffer the winter efficiency losses typical of systems that extract energy from the air.
Disadvantage: there are still relatively few installed systems on the market, and many installers and consultants have a “don’t know it, don’t build it” mentality.
The masonry heater has an incredible appeal to many people (including us) because of its very pleasant radiant heat. Since you don’t want to use wood continuously, I would install this as a “luxury” secondary system. You really need to be passionate about handling firewood to rely exclusively on such a system.
Our neighbors use a wood log gasification boiler for heating. These are now also available with automatic fuel feeding. I have no idea how reliable that is. This makes refueling easier, but the challenge of cutting or sourcing wood obviously remains.
Please keep in mind that these are just suggestions to encourage you to think outside the box – like many others here, I am not a professional. Most people here work with systems for new buildings, where the calculations are different.
B
boxandroof27 Dec 2019 12:35hampshire schrieb:
Heat pumps combined with underfloor heating are efficient heating systems. Since you have plenty of space and probably no rocky soil, I recommend looking into the ice storage heating system. It only becomes worthwhile with higher energy demands—which you likely have due to the large, older buildings. Alternatively, consider a horizontal trench collector (Ringgrabenkollektor). With some DIY effort and subsidies, it’s an efficient and cost-effective heat source without an outdoor unit. In Essen, an air-to-water heat pump can also work well, for example two 5 kW Panasonic air-to-water heat pumps costing about 2,500 € each. The latter has been specifically tested in older buildings, and you can find many completed projects online with descriptions from homeowners for both options.
The most important factors for all heat pumps are planning the heating surfaces, hydraulics, and sizing. It’s not that complicated, but unfortunately you can’t rely entirely on contractors, KfW planners, or others at this stage. Don’t lose focus due to possible subsidies. Plan first, then look into how to integrate funding.
H
hampshire27 Dec 2019 18:22guckuck2 schrieb:
As far as I know, ice storage costs around 40,000 euros. A complete dead end. You can drill a lot, dig, or extract heat from the air “inefficiently” for that price. The high costs you mentioned usually occur when a solar thermal system is used for energy recovery in the water tank – however, this is not mandatory.
By the way, this system works excellently for cooling in summer. Initial investment is higher, but operating costs are low.
Not everyone just wants the lowest price. The original poster will understand what I mean and can form their own opinion based on their criteria.
Renovation/modernization, etc., of a timber-framed farmhouse in a remote location: a demanding undertaking that requires a comprehensive overall concept. First, it should be clarified whether this "remote location" constitutes a planning-related situation according to § 35 of the Building Code, namely the so-called "outer area," which may involve restrictions on use or change of use.
Timber framing is a specific structural system, and different rules and materials apply for its (energy-related) renovation than for solid construction, in order to achieve lasting damage-free results.
The choice of a suitable heating system is inseparably linked to the scope and type of energy renovation (building insulation) and cannot be decided independently. This also includes a room-by-room heating load calculation for system dimensioning that considers the building’s insulation standard after renovation.
I strongly recommend discussing your planning considerations with an architect experienced in timber-frame construction, ideally one who is also skilled in building energy consulting for timber-framed buildings. The project should begin with an inventory survey that assesses the building’s condition and identifies potential structural damage as well as the associated repair requirements.
Based on this, a renovation concept can be developed that integrates all involved trades and takes into account the chronological sequence.
There is a planning methodology for this type of construction work that should definitely be followed to achieve a good result. This also includes as detailed and reliable cost calculations as possible.
Timber framing is a specific structural system, and different rules and materials apply for its (energy-related) renovation than for solid construction, in order to achieve lasting damage-free results.
The choice of a suitable heating system is inseparably linked to the scope and type of energy renovation (building insulation) and cannot be decided independently. This also includes a room-by-room heating load calculation for system dimensioning that considers the building’s insulation standard after renovation.
I strongly recommend discussing your planning considerations with an architect experienced in timber-frame construction, ideally one who is also skilled in building energy consulting for timber-framed buildings. The project should begin with an inventory survey that assesses the building’s condition and identifies potential structural damage as well as the associated repair requirements.
Based on this, a renovation concept can be developed that integrates all involved trades and takes into account the chronological sequence.
There is a planning methodology for this type of construction work that should definitely be followed to achieve a good result. This also includes as detailed and reliable cost calculations as possible.
B
boxandroof27 Dec 2019 23:04Which heating systems are unsuitable for timber-framed houses and why?
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