Ritterhof

Niedersonthofener Street 8

87448

Waltenhofen-Oberdorf, Germany

Architect

Michael Felkner
Niedersonthofener Straße 8, 87448 Waltenhofen-Oberdorf
felkner@architekt-felkner.de
+498379/7468

Contact Details

Alexandra Troi
Hochschule Coburg
alexandra.Troi@hs-coburg.de

Other Information

Visits
visit of the health food store possible

Michael Felkner
Step by step, always following the principle of the best possible solution, architect Michael Felkner is renovating the Ritterhof: the farmhouse from the late 17th century now houses his office and the flat for the family, but also a health food shop and a granny flat converted for age-appropriate living. The remaining heating needs are covered by wood and solar energy.
Energy performance
60 kWh/y

Climate Zone Dfb

Altitude 741

HDD 3730

CDD 47

Protection level Not listed

Conservation Area:
No

Level of Protection:

Building age 1850-1899

Year of last renovation:
2016

Year of previous renovation:
2005

Building use Residential (rural)

Secondary use:
Offices

Building occupancy:
Permanently occupied

Number of occupants/users:
6

Building area Net floor area [m²]: 703,0

Building typology:
Detached house

Number of floors:
3

Basement yes/no:
Da

Number of heated floors:
3

Gross floor area [m²]:
845,0

Thermal envelope area [m²]:
0,0

Volume [m³]:
5000,0

NFA calculation method:
NGF (de)

Construction type
The office and model workshop are made of quarry stone, the house is built in traditional Allgäu block construction and the shop and the upper floor are timber-framed

External finish:
Exposed woodwork

Internal finish:
Plastered (on substructure)

Roof type:
Pitched roof

+ MORE - LESS
Michael Felkner
Michael Felkner
Michael Felkner
Michael Felkner
Michael Felkner
Michael Felkner
Michael Felkner
Michael Felkner
Michael Felkner
Michael Felkner
Michael Felkner
Michael Felkner
Michael Felkner
Michael Felkner
Michael Felkner
Michael Felkner
Michael Felkner
Michael Felkner
Michael Felkner
Michael Felkner
Michael Felkner
Michael Felkner
Michael Felkner
Michael Felkner

RENOVATION PROCESS

Architecture

BUILDING DESCRIPTION

The oldest parts of the house, built in traditional Allgäu block construction, probably date from the late 17th or early 18th century. The residential part is shingled from the first floor upwards and, with the exception of the hallway, has a cellar. In the cellar there used to be a home dairy - which was probably installed here in the mid-19th century as a precursor to a village dairy with the changeover from arable farming to grassland farming and dairy cattle husbandry in the Allgäu. With the change in farming methods, the space requirements for stables and fodder storage rooms increased, so that this building was probably enlarged at the end of the 19th century by one room axis to the north and by a multiple of the original farm part and provided with a completely new roof truss. On the north side, a so-called "Wiederkehr" with stables was added. The stables are of quarry stone masonry, the adjoining and overlying barns of timber frame construction.
Urban context
The surroundings of the Ritterhof are characterised by villages.

HERITAGE SIGNIFICANCE

ELEMENTS WORTHY OF PRESERVATION
Formally, the Ritterhof is not a listed building, but the builders attached great importance to getting to know and understand the building as part of the renovation, to preserve its structure and to keep its history legible. For example, the rubble stone walls were refurbished, the timber frame structures were supplemented using timber construction, and the shingled south and east façades of the dwelling house were not altered. The parlour of the dwelling house was also not insulated, because old wall panelling came to light during the renovation, which was to be preserved.
Heritage Value Assesment
The building is not formally listed, but has been declared by KfW as a "building structure particularly worthy of preservation" for funding purposes.

State of repair

Conditions of the envelope
The building that existed in 1989 had a usable area of about 1000m² and a reconstructed room of about 5000m³. The roof over the living area was earlier already reconstructed, whereas the attic was yet not developed and also the roof coves were leaking. The cowshed was built with natural stone and there was a wooden beam ceiling. The barn was built as a timber-framed structure and contained only natural ground as subfloor. The recurrence was bricked in the ground floor area and the upper floor was designed as a timber-frame construction, where cap ceilings were used in this part of the building. In addition to this, only single glazed windows were installed throughout the building. Only single ovens were available for heating. Furthermore, the old farmhouse was not connected to the public sewage system. The electrical and sanitary installations were from the 1950s and accordingly outdated.
Description of pre-intervention building services
Only single ovens were available for heating. Furthermore, the old farmhouse was not connected to the public sewage system. The electrical and sanitary installations were from the 1950s and accordingly outdated.

Aim of retrofit

Renovation + Extension
Living and working in it comfortably and seeing what else is possible in terms of sustainable use that does justice to the building: when the current owner took over the building in 1989, he first had 5,000 m³ of enclosed space at his disposal, but as a young architect he had hardly any budget. He began with the most urgent measures such as connecting the building to the sewage system and repairing the roof. And then developed a utilisation (and renovation) concept that could be implemented flexibly and step by step. In the course of the renovation measures, the principle of the best possible solution was to be followed, also by using sustainable and ecological materials from the surroundings and relying heavily on solar energy - thermal, photovoltaic and passive. In the process, (a) the barn was converted into a 122 m² architect's office, with component temperature control and wall-radiation heating and a solar share of 70% in the heating system, (b) in the Wiederkehr 79 m² granny flat as a Factor 10 renovation with passive house technologies, ventilation with heat recovery, solar, wood, (c) in the old barn 140 m² health food shop, as such zero heating energy, when converted into a flat still a 3-litre house, (d) in the old block building 360 m² flat, which can later be divided into two units. The attic and the space above the office and shop can still be converted.
Was there any change of use?
The former cow and horse stables were converted into an architectural office and the hay warehouse was turned into a health food shop. The attic was converted into a granny flat suitable for senior citizens and partially barrier-free.
Was the intervention planned following a step-by-step approach?
The renovation of the Ritterhof took place in several phases. The first. Phase lasted from 1989 to 1991, during which the necessary electrical installations, the existing bathroom and the roof over the return were renewed. The house was also connected to the public sewerage system. The second one. Phase took place in 1998 and 1999. Here the former stable was converted into an architectural office and the barn into a health food shop. A large solar system with storage technology was installed. In addition, the gas condensing boiler was replaced by a logwood boiler. On the third. In the second phase from 2006-2007, the energetic renovation of the partially handicapped-accessible apartment was tackled, whereby the aim was a low-energy house in the existing building (NEHB). The last phase started in 2005, whereby the residential part was renovated in several construction phases. In addition, the photovoltaic and thermal solar system including storage technology was expanded and upgraded. In 2008, the decommissioned gas tank was replaced by a 4850 litre buffer storage tank for the 40m² solar system. In 2016, the natural food shop was reduced to create a disability-friendly apartment. In 2018, the timber boiler was replaced by pellet boiler and the storage was optimized.
Lessons learned
The energetically sensible conversion and renovation of old farms is a demanding task. It is necessary to act in time and above all to renovate energetically, because non-natural energy sources are becoming more and more expensive. Step by step, the architect tried out on his own building what he was also planning for others and experimented a lot with materials, implemented many things himself and thus understood them all the better.
Stakeholders Involvement
Architect
Michael Felkner
Niedersonthofener Straße 8, 87448 Waltenhofen-Oberdorf
felkner@architekt-felkner.de
Tel.+498379/7468
Tools used
Was the renovation process done following a specific methodology? No
Energy calculation Rechenprogramm „Wärme und Dampf“, Dämmwerk (EnEV und Wärmebrücken), BKI (EneV und Wärmebrücken)
Hygrothermal assessment WUFI (Wärme- und feuchteschutztechnische Simulation)
Life Cycle Analysis (LCA) -
Other Solartechnik, Bauteiltemperierung und Passivhaustechnik

RETROFIT SOLUTIONS

External Walls

Shingled walls of the residential part

Northern wall of the residential part

Walls of the granny annexe

Quarry stone walls of the stable

Walls of the barn, today a shop

Shingled walls of the residential part

Since the shigles on the southern and western facade of the residential building were very weAfter the application of a wind paper approx. 16cm flexible wood fibre mats installed, on top of this wood boarding, clay building boards, wall radiant heating and clay plaster. This construction has the advantage that moisture can dry off both to the room and to the outside.ll preserved, these walls were insulated from the interior.

In the parlour, the only room in the 360m² house, the two outer walls remained without insulation, because the renovation revealed a beautiful old wall panelling that was to be preserved. Therefore, when installing the new windows and repairing the panelling, only the tightness was improved.

U-value (post-intervention) [W/m2K]: 0,18 W/m²K
More Details
Original wall build-up
Retrofitted wall build-up
Cladding - Schindeln (trägt nicht zu U-Wert bei):
20mm
Air gap - Hinterlüftung (trägt nicht zu U-Wert bei):
40 mm
Wood - Blockwand:
160 mm
Other - Windpapier:
1 mm
Insulation - Holzweichfaserplatte:
160 mm
Other - Lehmbauplatte mit Wandheizung:
0 mm
Plaster - Lehmputz:
20 mm
Northern wall of the residential part

The plastered, almost windowless north side of the building was doubled up on the outside with squared timbers, blown out with 28 cm cellulose in between and covered on the outside with softwood fibreboard and clad with vertical wooden boarding.

This meant that no characteristic element of the building was lost, and external insulation is easier to implement in terms of building physics.

U-value (post-intervention) [W/m2K]: 0,115 W/m²K
More Details
Original wall build-up
Retrofitted wall build-up
Wood - Holzschalung (trägt nicht zu U-Wert bei):
0mm
Air gap - Hinterlüftung (trägt nicht zu U-Wert bei):
0 mm
Insulation - Holzweichfaserplatte:
20 mm
Insulation - Zellulose:
280 mm
Wood - Blockwand:
160 mm
Other - Lehmbauplatte mit Wandheizung:
0 mm
Plaster - Lehmputz:
20 mm
Walls of the granny annexe

The annex in the north (today: granny annexe) had an externally timber-clad timber frame construction. After gutting, 9 columns remained, between which, as in the new building, new wooden stud walls were placed, which were given a stiffening and airtight planking with OSB boards on the room side. On the outside, the studs were planked with a latex-impregnated softwood fibreboard under rough-sawn larch wood formwork. On the room side, an installation level was provided and clad with economy formwork and wooden clay panels. The walls were then plastered with clay.

U-value (post-intervention) [W/m2K]: 0,1 W/m²K
More Details
Original wall build-up
Retrofitted wall build-up
Quarry stone walls of the stable

The former cow and horse stables are built of approx. 60 cm thick quarry stone masonry and, due to the lack of a horizontal moisture barrier, transported massive amounts of moisture upwards from the subsoil. Installing a damp-proof barrier was not an option due to the unstable statics, and injections did not seem very promising in view of the cavities between the quarry stones. The only way to dry out the masonry would be to use the so-called component temperature control system, in which 30-gram water flows through a copper pipe installed in the plinth area all year round.

Since only a small part of the masonry is an exterior wall, the heat loss is acceptable.

More Details
Original wall build-up
Retrofitted wall build-up
Walls of the barn, today a shop

For the shop space, the exterior walls were completely renewed (in reinforced concrete or masonry) and well insulated on the outside.

U-value (post-intervention) [W/m2K]: 0,2 W/m²K
More Details
Original wall build-up
Retrofitted wall build-up
:
0mm
:
0 mm


Windows

Windows upper floor

Window ground floor

Windows upper floor

In 2008, the windows on the upper floor were changed to triple glazing: natural larch wood windows were installed, the pitch of which is oriented towards the existing building. The circumferential reveal frame allows the layers of the wall construction to be tightly connected.

The old windows were single glazed and frost patterns regularly formed on the windows.

Existing window U-value Glass [W/m2K]: 5,7 New window U-value Glass[W/m2K]: 0,6 Existing window U-value Frame [W/m2K]: 2,1 New window U-value Frame [W/m2K]: 0,6
More Details
Existing window type Double window
Existing glazing type Single
Existing shading type Outer shutter
New window type Double window
New glazing type Triple
New shading type The Ritterhof has partly rigid sun protection and folding shutters.
New window solar factor g [-] 0,0
Window ground floor

The windows on the ground floor were replaced with double glazing in 2004.

The old windows were single glazed and frost patterns regularly formed on the windows.

Existing window U-value Glass [W/m2K]: 5,7 New window U-value Glass[W/m2K]: 1,1 Existing window U-value Frame [W/m2K]: 2,1 New window U-value Frame [W/m2K]: 1,1
More Details
Existing window type Double window
Existing glazing type Single
Existing shading type Outer shutter
New window type Double window
New glazing type Double
New shading type The Ritterhof has partly rigid sun protection and folding shutters.
New window solar factor g [-] 0,0

Other interventions

ROOF

GROUND FLOOR

MEASURES TO INCREASE AIRTIGHTNESS

ROOF

When the Ritterhof was acquired, the roof was leaking and had to be renewed. In 1989, the roof was renovated - in the first approach without energetic measures, and with the option of making the roof spaces usable in the future.

In the meantime, the attic of the granny flat has been developed and the roof slope has been insulated with 22 plus 8 cm of insulation. In the other areas, the top floor level remains the thermal envelope: In the block building, the ceiling to the undeveloped attic was insulated between and under the beams with soft wood fibre boards, and the ceiling above the shop and office was also insulated with 20-26 cm insulation.

U-value (post-intervention) [W/m2K] 0.2
More Details
Original roof build-up
:
0 mm
Retrofitted roof build-up
GROUND FLOOR

In the stable the wooden floor was removed, the soil was excavated down to the foundation level, a concrete floor slab with 20cm of thermal insulation was installed and a floor covering of OSB boards was built on top. An equivalent approach was taken with the grown floor of the barn when the shop was removed.

The false floor of the wooden beam ceiling above the natural cellar (under the residential house) was renewed and provided again with a moisture-regulating clay coating, whereby the remaining cavity was filled with wood shavings for insulation and an airtight layer of soft wood fibre boards was inserted above it. Solid wood flooring was installed throughout.

U-value (post-intervention) [W/m2K] 0.2
More Details
Original groundfloor build-up
Retrofitted groundfloor build-up
MEASURES TO INCREASE AIRTIGHTNESS

In all measures, attention was also paid to air tightness, especially at the transition from one component to another. This is illustrated here by the example of the granny annexe: During the renovation, new wooden post-and-beam walls were placed between the columns, which were given a bracing and airtight planking of OSB boards on the room side. For the floor, beams were laid on the brick cap ceiling, the spaces between them being filled with wood shavings. OSB boards also serve as the support material for the floor structure. This created a stiffening and tight envelope all around. However, the puncture points of three load-bearing beams of the roof construction detract from the result of the airtightness test, because the cracks in the old beams simply could not be made 100% tight.

Airtightness (pre-intervention) [ach@50Pa] - Airtightness (post-intervention) [ach@50Pa] -

HVAC

HEATING

VENTILATION

DOMESTIC HOT WATER

HEATING

In the beginning, the Ritterhof was only heated with individual stoves. In 1998 a gas boiler with wall radiant heating was installed throughout the building. In 2000 the gas boiler was replaced by a log boiler. In 2018, the logwood boiler was replaced by a pellet boiler with optimized storage tank. In the residential house, the kitchen and the living room are not connected to the central heating system, as the stove there is enough to keep comfortable temperatures.

In the kitchen of the granny annexe there is a room-air-independent Greithwald cooker with heat exchanger, which heats the installation room during the heating period and enables cooking and baking at the same time. Excess heat is fed into the storage tank and reaches the other rooms via the wall-mounted radiant heating surfaces, so that the tenants only have to light a fire every other evening in winter.

More Details
New primary heating system New secondary heating system
New system type Boiler Stove
Fuel pellets Wood
Distribuition system Radiating wall Air
Nominal power 32 kW kW
VENTILATION

The individual building areas are also equipped differently in terms of ventilation: The granny flat, generally renovated with passive house components, has a ventilation system with heat recovery. The architect's office is naturally ventilated (4-5 people on 100m²), but a ventilation system was considered and can easily be added.

In the shop, the 36W fan built into the wall allows excess heat to be removed from the salesroom in the morning hours during the summer and cool air to be drawn in via a supply air opening on the north-west side.

More Details
Original roof build-up New ventilation system
Type ventilation system Depending on area
Type flow regime NA (Natural)
Heat recovery No
Humitidy recovery No
Nominal power - kW
Electric power kW
Control system -
DOMESTIC HOT WATER

At the beginning of the renovation measures, the Ritterhof had no connection to the sewage system.

Today, the domestic hot water is mainly heated by the pellet boiler, with a solar system supporting the heating and covering most of it in summer.

More Details
New DHW system
Type with heating system
Hot_water_tank Da
With heat recovery No

RENEWABLE ENERGY SYSTEMS

SolarThermal

Photovoltaic

Biomass

SolarThermal

In 1998, the Ritterhof got its first solar system with 20 m² and buffer storage (1700 l), which heats the architectural office with a solar coverage of about 70%. In 2008, as part of the renovation of the family home, this was enlarged to 40m² and the buffer storage was increased to 4850 litres (for which the obsolete gas tank was converted). The granny annexe has its own solar system with 12m² of solar panels and 700l buffer tank, hich completely covers the hot water demand outside the heating period.

The solar system is barely visible on the only slightly sloping roof.

More Details
SolarThermal System
Type Flat collector
Collector area 52,0 m²
Elevation angle 35,0
Azimuth 0,0
Overall yearly production 0,0 kWh
Heating_contribuition 0,0 kWh
DHW contribuition 0,0 kWh
Cooling contribuition 0,0 kWh
Photovoltaic

In 2004 a PV system with 4. 4 kWp was installed and in 2008 a further one with 9. 68 kWp was installed on the southern roof.

The consumption of electrical energy is roughly congruent with the yields from the installed photovoltaic system, which is barely visible on the only slightly sloping roof.

More Details
Photovoltaic System
Type
Collector area 90,0 m²
Total nominal power 14,0 kW
Elevation angle 35,0
Azimuth 0,0
Overall yearly production 15000,0 kWh
Heating contribuition 0,0 kW
DHW contribuition 0,0 kW
Cooling contribuition 0,0 kW
Lighting contribuition 0,0 kW
Biomass

Main heating of the building is a pellet heating system

In the living area, the parlour and kitchen are heated by a basic stove and tiled stove.

The granny flat, on the other hand, is heated via the Greithwald heart (heating every other day, see HVAC).

More Details
Biomass System
Type Pellet
Storage size
Origin of biomass
Overall yearly production 42750,0 kWh

Energy Efficiency

Energy Performance
Energy performance certificate: No
Voluntary certificates: In 2007 the Ritterhof was awarded the first place of the KfW Energy Efficiency Award “Energetic Modernization of Commercial Buildings. ” Architectural office in 3-litre standard - 33kWh/m²a solar coverage 70%. Natural food shop: no heating energy as shop, 33kWh/m²a for residential use. Granny flat with passive house technology in 3-litre standard: dena model project Factor 10 refurbishment.
Energy Use
Heating
Consumption_estimation_Calculation_method: Derived from energy bills
Consumption_estimation_After: 60 kWh/y

Primary Energy
Consumption_estimation_Calculation_method: Derived from energy bills
Consumption_estimation_Including_DHW: Da
Consumption_estimation_After: 12 kWh/m2.y

Internal Climate

Temperature

Thanks to the renovation, the rooms are now evenly warm, due to the well-insulated basement ceiling. The wall jet heaters on the well-insulated exterior walls in combination with the mud plaster create a particularly pleasant atmosphere.

Indoor Air Quality

In order to achieve good air quality, regular ventilation is required, as there is no ventilation system and the new windows are airtight.

Acoustic Comfort

The house is not comparable with a new building (in timber construction) in terms of sound insulation.

Costs

Financial Aspects

Various funding for the renovation. In 2005, the architect received an award from dena (German Energy Agency) for the renovation of the granny annexe and the return above the former horse stable.

Running Costs
Lifecycle cost
No

In order to give you a better service this site uses cookies. Additionally third party cookies are used. By continuing to browse the site you are agreeing to our use of cookies. More information