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Modernizations at Wildenowstraße 20: We are creating living spaces with a future
* This page has been translated via Google's Cloud Translation API. HOWOGE does not edit the content.
We improve your quality of life! Your house will be renovated!
Good day,
Starting in early May of this year, we will be modernizing the residential building in which your apartment is located. This will improve your quality of life in the long term. The following measures will be carried out:
in your apartment:
- Window (4.)
- Ventilation (6.)
Additionally at the residential building:
- Roof (1. *)
- Entrance area (2.)
- Facade (3.)
- Loggias/balconies (5.)
*A detailed description of the measures and the planned construction times can be found in Appendix 4.
You can remain in your apartment during the renovation work. However, there will be some temporary restrictions.
Naturally, we will do everything we can to ensure the construction work proceeds quickly and smoothly. We thank you for your understanding and will strive to minimize any inconvenience.
1. Important – please fill out and submit by March 6, 2026:
Please complete the declaration of consent (Annex 1) and the data protection declaration (Annex 2) according to the required information and send them to us by 06.03.2026 to kundenzentrum@howoge.de .
Furthermore, we would like to remind you to inform your household insurance company about the period during which scaffolding will be erected. You are welcome to use the attached form 3 for this purpose.
2. Information on the construction period
Construction work will begin on May 4, 2026 and is expected to end on September 28, 2026 .
Access to your apartment by specialist companies commissioned by us will likely be necessary from April 20th, 2026 to May 1st, 2026. We kindly ask you to ensure that the area is clear for construction. We will explain the extent of this access required at a separate appointment in your apartment. We will inform you of this appointment separately.
Should you require assistance in creating the necessary space for construction in your apartment, please contact us immediately after the on-site inspection.
If the planned construction dates are postponed (see Appendix 4), we will announce this in a timely manner. Naturally, no construction work will take place on public holidays within the specified periods.
3. Do you require support during the construction period?
If you have any questions or require assistance due to your age or a physical disability, please feel free to contact us:
- by telephone: 030 / 54 64 28 00
- by email: kundenzentrum@howoge.de
4. Investment costs and modernization levy
We anticipate investing a total of €963,153.45 in this construction project. We will finance the planned repair and modernization measures with loans from the KfW Development Bank and the Berlin Investment Bank (IBB). Since we are receiving these loans at favorable interest rates, we will pass on the difference between the loan interest rate and the market interest rate at the time of project completion to you in the form of a reduction in your service charges. We have already received preliminary loan approvals from the lenders. However, these do not yet reflect the final loan amount. This will only be determined once the final accounting at the end of the project provides concrete evidence of how the funds were used.
Because neither the final loan amounts nor the prevailing market interest rate are yet known at the time of completion of the construction project, we cannot calculate an estimated interest rate reduction amount for you at this time. This can only be done after the work is completed.
The costs for all maintenance work will be covered by us, HOWOGE. We will only pass on the costs for modernization measures to your total rent, in accordance with legal regulations and the requirements of the Berlin Senate.
| Total cost of this measure: | Amount |
| of which total repair share: | Amount |
| of which the total modernization share is: | Amount |
| Monthly modernization levy absolutely before capping: | Amount |
| Monthly modernization levy per m² before capping: | Amount |
| Cap amount per m²: | Amount |
| Monthly modernization levy per m²: | Amount |
| Your estimated monthly modernization levy: | Amount |
Please note that this breakdown is based on estimated costs. Only after the work is completed can we provide you with information on the actual costs incurred and the resulting monthly charges, as part of the modernization billing . At the same time, we expect the planned measures to reduce your heating and hot water costs, assuming your usage remains unchanged.
For this reason, we ask you to refrain from asking about the specific amount of the levy until the modernization bill is issued.
Please refer to Appendix 6 for legal information regarding the modernization measure.
5. Affordability guarantee, hardship clause and special right of termination:
With the cooperation agreement "Affordable Rents, New Housing Construction, and Social Housing Provision," we promise affordable rents. This affordability promise ensures that the burden of net rent on each household does not exceed 27% of its household income, provided that the income limits relevant for a housing entitlement certificate (WBS) and the living space limits according to Article 2, Section 3, Paragraph 4 of the Berlin Housing Act (WoVG Bln) are not exceeded. Tenants can apply for a rent reduction to this percentage in relation to their income.
We would like to inform you today that you may be entitled to housing benefit due to the present modernization announcement.
We hereby inform you that, in accordance with Section 555d Paragraphs 2, 3, 4 of the German Civil Code (BGB), you must notify us in writing of all circumstances that justify hardship with regard to your toleration by the end of the month following receipt of the modernization notice.
Furthermore, we would like to point out that you have a special right of termination at the end of the second month following receipt of the modernization notice, pursuant to Section 555e Paragraph 1 of the German Civil Code (BGB). The termination notice must be given by the end of the month following receipt of the modernization notice.
5. Further information for you:
More detailed information on the measures and legal notices can be found in:
- Annex 1: Declaration of Toleration
- Appendix 2: Information and declaration on data protection – Disclosure of contact details
- Annex 3: Notification to the household contents insurer
- Annex 4: Description of the construction measures
- Annex 5: Cost splitting and modernization levy
- Annex 6: Legal information regarding the upcoming modernization
- Appendix 7: Floor plan
Best regards
Your HOWOGE housing company mbH
Annex 1:
name
Willdenowstraße 20
13353 Berlin
HOWOGE Wohnungsbaugesellschaft mbH
PO Box 10 03 19
57003 Siegen
Declaration of Toleration
The announcement letter stated the start date, expected duration, type and scope of the work, as well as the expected timeframes.
I/we will tolerate the modernization and repair measures in the house announced in the letter of 04.2.2026 and will grant corresponding access to the apartment and the tenant's cellar, insofar as this is necessary for the aforementioned measures.
Berlin, the
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name
Annex 2: Tenant number: Contract
name
Willdenowstraße 20
13353 Berlin
HOWOGE Wohnungsbaugesellschaft mbH
PO Box 10 03 19
57003 Siegen
Privacy notice and statement – Sharing of contact details
In the event of necessary repairs, maintenance, renovations, refurbishments, or similar work, HOWOGE generally uses external service providers (e.g., tradespeople). In this case, scheduling an appointment between the tenant and the service provider is required. Furthermore, data must be shared with the following recipient: Studio Duktus Buser Architekten PartGmbB.
The tenant hereby consents to the following communication data being transmitted to external service providers:
☐ Phone number / Phone number ________________ /__________________
☐ Email address ____________________________________
This data will only be passed on to the external service provider so that an appointment can be arranged quickly.
Consent is given voluntarily. I/We am/are aware that this consent can be withdrawn at any time.
Even if the tenant does not consent to the aforementioned data processing, the necessary measures will be carried out. This consent is given voluntarily and can be revoked at any time without stating reasons, with effect for the future.
_______________________________ ____________________________________
Place, Date, Signature of Tenant
We would like to refer you to our privacy policy, which you can view at any time at www.howoge.de/datenschutz.html.
The data protection officer can be reached at datenschutz@howoge.de.
Attachment 3: (Please send to your insurance company)
Insurance company address: Tenant's details:
policyholder
Notification to the household contents insurer
Good day,
From May 4th, 2026 to September 28th, 2026, modernization and repair work will be carried out at Willdenowstraße 20, 13353 Berlin by HOWOGE Wohnungsbaugesellschaft mbH, the building's manager. The building will be scaffolded for this purpose.
Best regards
Berlin, the
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Signature Name
Annex 4: Description of the construction measures
Roof - Construction period in calendar weeks (CW): June 1, 2026 to July 3, 2026
It's on
The ceiling between the heated apartments on the 4th floor and the unheated attic is not insulated. This leads to heat loss and therefore unnecessarily high energy consumption.
Construction measures and consequences
The ceiling is insulated from above, from the side of the attic, with 22 cm thick mineral wool insulation (thermal conductivity 0.035 W/(m·K)). A vapor barrier is installed below the insulation, and a vapor-permeable membrane above it.
Added value (before-and-after comparison)
The new 22cm thick mineral wool insulation (WLG 035) in the attic ceiling significantly reduces heat loss, leading to lower energy consumption and improved living comfort. The existing heat transfer coefficient of approximately 0.9 W/(m²K) for the ceiling structure above the unheated attic space will be reduced to 0.13 W/(m²K) by the insulation on the ceiling's upper surface. This corresponds to a reduction in heat transfer of approximately 86%.
Measures that sustainably reduce final energy consumption are considered modernizations according to Section 555b Paragraph 1 of the German Civil Code (BGB). We will include a portion of the attic insulation costs in the modernization surcharge and classify the remaining costs as repairs.
Entrance area - Construction period in calendar weeks: May 4, 2026 to September 28, 2026
It's on
The front door is outdated and no longer meets current standards. The wooden doors to the courtyard are also old and need to be refurbished to improve both their functionality and appearance.
Construction measures and consequences
The old front door will be replaced. The two courtyard doors will be repaired and repainted to restore them to a well-maintained condition. The door to the rear building will remain in its current good condition and will not be altered.
We will treat all costs of this measure as repairs and will not levy any additional charges.
Facade - Construction period in calendar weeks: May 4, 2026 to September 28, 2026
It's on
The facade is not insulated and has been badly damaged by the demolition of the balconies. This leads to heat loss, increased energy consumption, and also negatively impacts the overall appearance of the building.
Construction measures and consequences
The old plaster is removed, the building is newly insulated and plastered with a thermal insulation composite system (ETICS) in accordance with the current requirements of the Building Energy Act (GEG).
Based on the available planning documents, the thermal insulation parameters for the relevant wall thicknesses of the exterior walls were calculated as follows:
- Wall thickness 36.5cm: U ≈ 1.54 W/(m²K)
- Wall thickness 49.0cm: U ≈ 1.24 W/(m²K)
- Wall thickness 61.5cm: U ≈ 1.04 W/(m²K)
To qualify for funding under the BEG (Federal Energy Act), the heat transfer coefficient must be limited to U ≤ 0.20 W/(m²K), which is achieved regardless of the existing wall thickness by installing a 16 cm thick external thermal insulation composite system (ETICS). The heat transfer coefficients and the expected reductions in heat loss through the exterior walls are as follows:
- Wall thickness 36.5cm with 16cm insulation: U ≈ 0.20 W/(m²K) Reduction of approx. 87%
- Wall thickness 49.0 cm with 16 cm insulation: U ≈ 0.19 W/(m²K) Reduction of approx. 85%
- Wall thickness 61.5cm with 16cm insulation: U ≈ 0.19 W/(m²K) Reduction of approx. 82%
For the ceiling structure above the unheated attic space, the existing heat transfer coefficient of approximately U=0.9 W/(m²K) will be reduced to U=0.13 W/(m²K) by insulating the ceiling surface. This corresponds to a reduction in heat transfer of approximately 86%.
We kindly request that you, as applicable, remove your satellite dish yourself two weeks before construction begins. Otherwise, we will remove and store it until the respective owner collects it. Furthermore, we would like to point out that re-installation by us is prohibited due to the new facade insulation.
Please inform your home insurance company in good time about the period the scaffolding will be erected. Access to your apartment is not necessary for the facade work.
Added value (before-and-after comparison)
The new thermal insulation reduces energy costs, leading to long-term savings on heating bills and significantly increasing living comfort. In addition, insulation is being installed to improve soundproofing against external noise. Furthermore, the new plaster enhances the building's exterior appearance.
Measures that sustainably reduce final energy consumption are considered modernizations according to Section 555b Paragraph 1 of the German Civil Code (BGB). We will include a portion of the insulation costs in the modernization surcharge and classify the remaining costs as repairs.
Windows - Construction period in calendar weeks: May 25, 2026 to July 6, 2026
It's on
The windows are outdated and mostly made of wood or, in some cases, old plastic. This results in higher heat loss and potential leaks, which not only reduce living comfort but can also lead to increased heating costs.
Overall, the existing windows do not meet current energy efficiency requirements.
Construction measures and consequences
Old wooden or plastic windows are replaced by modern, white plastic windows with triple glazing and plastic frames.
For the different window types in existing buildings, the following thermal insulation parameters typical for the construction period can be assumed as approximate values:
- Existing wooden box window with two single panes of glass: UW ≈ 2.7 W/(m²K)
- Existing timber composite window with two single panes of glass: UW ≈ 2.8 W/(m²K)
- Existing single-pane plastic windows with insulating glass (1990s): UW ≈ 1.8 W/(m²K)
To qualify for funding under the BEG (Building Energy Act), the windows must be replaced, ensuring a U-value of ≤ 0.95 W/(m²K). This results in the following reductions in U-values and heat losses through the windows:
- Wooden box window: UW ≈ 2.7 W/(m²K ->UW ≤ 0.95 W/(m²K) reduction by approx. 65%
- Wood composite windows: UW ≈ 2.8 W/(m²K) ) -> UW ≤ 0.95 W/(m²K) Reduction by approx. 66%
- Plastic windows: UW ≈ 1.8 W/(m²K) -> UW ≤ 0.95 W/(m²K) Reduction of approx. 47%
Additional window flashing will be installed on the exterior. New window sills, both functional and visually appealing, will be installed on the interior.
As part of the window replacement in your apartment, we will check all fall protection systems on the windows and install appropriate fall protection systems if the required parapet height is not met.
The stairwell windows will not be replaced, but repaired and repainted to preserve the charm of the old building while making it look more well-maintained.
The tenants' cellars facing the street must be provided with a clearance of 1.5 m around the windows if necessary; if their cellar is affected, this will be discussed at the on-site appointment.
The window work in your apartment is expected to take 2-3 days. The construction company will notify you of the exact date in due course.
You can see where you need to provide clearance for construction from the floor plan in Annex 7.
Added value (before-and-after comparison)
The new windows will be leak-free and significantly reduce heat loss. This will increase living comfort and lower energy costs. Additionally, the newly installed window sills provide reliable weather protection. They protect the windows and the surrounding building structure from rain, wind, and moisture, thus preventing damage and considerably extending the windows' lifespan.
To achieve a heat transfer coefficient of UW ≤ 0.95 W/(m²K) according to the BEG-EM specifications, it is assumed that triple insulating glazing with a heat transfer coefficient of the glazing of Ug ≤ 0.6 W/(m²K) in conjunction with multi-chamber plastic frames with a heat transfer coefficient of the frame constructions of UW ≤ 1.20 W/(m²K) and a thermally optimized edge seal can be used.
Measures that sustainably reduce final energy consumption are considered modernizations according to Section 555b Paragraph 1 of the German Civil Code (BGB). We will include a portion of the costs of these measures in the modernization surcharge and classify the remaining costs as maintenance.
Loggias/Balconies - Construction period in calendar weeks: June 8, 2026 to June 9, 2026
It's on
The old balconies were removed, damaging the facade. The load-bearing elements are now visible, which can be problematic both aesthetically and from a structural engineering perspective.
Construction measures and consequences
We will only be installing new cantilevered balconies in the front building (1st to 3rd floors). On the 4th floor of the front building, the Juliet balconies will be removed and replaced at all floor-to-ceiling windows.
New balconies not only provide additional private outdoor space for residents, but also contribute significantly to improving the external appearance of the house.
We will treat all costs of this measure as repairs and will not levy any additional charges.
Ventilation - Construction period in calendar weeks: June 30, 2026 to June 30, 2026
It's on
The building has no fans, meaning that ventilation can only occur by opening the windows. As a result, air circulation is often irregular and heavily dependent on external weather conditions. Regular ventilation can be particularly difficult in bad weather or when there is noise from outside, which can negatively affect air quality and the indoor climate.
Construction measures and consequences
As part of the modernization, reveal insulation ventilators are being installed. We basically have three concepts.
1. The interior bathroom in apartment 0502 will be connected to the existing ventilation shaft.
We are connecting the new electrically operated ventilation units to the existing ventilation duct. The new units will be powered by electrical outlets (possibly at the light switch) connected to the existing electrical circuit. These 12V units will be connected to the 230V circuit via an adapter and will have their own control switch. This switch must be located outside the protected area of the bathrooms.
2. Electrically connected fans on the facade (kitchens and bathrooms on the facade).
In most cases, these are reveal vents. Where the room geometry doesn't allow for this, the vent runs straight through the facade. These vents are also connected to the electrical circuit as described above. There is a special case for the interior bathrooms in the side wing, as well as bathrooms 0302, 0402, and 0503.
To minimize disruption for the tenants, the necessary fan will be positioned in the wall between the bathroom and kitchen, and we will connect the bathroom to the facade via a circular duct running through the kitchen. Ventilation grilles will then be installed in the facade, passing directly through the wall. All wiring for the electrically connected fans will run along the surface of the wall at the junction of the wall and ceiling to the nearest electrical outlet. The 230V adapter will also be installed there.
3. Non-electrically connected fans.
These fans operate without a connection, simply based on the physical principles of negative and positive pressure, in conjunction with electrically connected fans. These are recessed fans.
Added value (before-and-after comparison)
Window reveal ventilators provide controlled and efficient ventilation without the need to open windows. This ensures continuous air exchange, preventing moisture and mold growth while minimizing heat loss. Another major advantage of window reveal ventilators is their discreet installation within the window reveal. Where possible, facade ventilators are integrated into the window reveals in the exterior walls of the 16 apartments. Electrical connections are made to the existing wiring at the access doors to the rooms. The wiring runs surface-mounted on the wall at ceiling level to minimize disruption.
This will lead to a lasting improvement in general living conditions and, according to Section 555b Paragraph 5 of the German Civil Code (BGB), qualifies as a modernization. We will include a portion of the costs in the modernization surcharge and classify the remainder as repairs.
Annex 5: Cost splitting and modernization levy
Calculation basis:
| Total living area: | Value m² | Your living space: | Value m² |
|---|
| trade | Total costs including ancillary construction costs in € | Maintenance costs in € | Modernization costs in € | Modernization surcharge in €/m² |
| 1. Roof | Amount | Amount | Amount | Amount |
| 2. Entrance area | Amount | Amount | Amount | Amount |
| 3. Facade | Amount | Amount | Amount | Amount |
| 4. Window | Amount | Amount | Amount | Amount |
| 5. Loggias/Balconies | Amount | Amount | Amount | Amount |
| 6. Ventilation | Amount | Amount | Amount | Amount |
| sum | Amount | Amount | Amount | Amount |
To keep your rent burden as low as possible, we will limit the modernization surcharge to a maximum of €2.00/m² of living space within six years, based on the applicable cooperation agreement between the Berlin Senate and the state-owned housing companies. Since the aforementioned modernization surcharge is higher than €2.00/m², it will be capped . The modernization surcharge as stated on page 2 of this letter, under point 3, applies; this amount will be charged monthly for your apartment.
Annex 6: Legal information regarding the upcoming modernization
Pursuant to Sections 555b and 555d Paragraph 1 of the German Civil Code (BGB), you are obligated to tolerate modernization measures. We therefore request that you declare your acceptance of the announced measures (Appendix 1) and provide your consent to the transfer of personal data (Appendix 2).
Please feel free to use the contact methods described above.
As you have gathered from our previous explanations, some of the measures implemented qualify as modernization, as they improve the rental property and save on heating energy and water – § 555b Nos. 1 to 7 of the German Civil Code (BGB). In accordance with §§ 559 et seq. of the German Civil Code (BGB) and the regulations in the Berlin Housing Supply Act (WoVG Bln) or the applicable cooperation agreement between the Berlin Senate and the municipal housing companies, we are entitled to distribute the resulting modernization costs among the individual apartments in a reasonable proportion.
In accordance with legal regulations, we can increase the annual rent by 8% of the incurred costs, § 559 para. a1 BGB. To keep your rent burden as low as possible, we will limit the modernization surcharge to a maximum of €2.00/m² of living space within six years, based on the applicable cooperation agreement between the Berlin Senate and the state-owned housing companies. The exact calculation basis and the resulting rent increase will be taken into account at the time of billing.
Since this is an energy-efficient renovation, we would like to politely point out that the legislator has excluded the right to a rent reduction for a period of three months with § 536 para. 1a BGB.