GENERAL INFORMATION RENOVATION PROCESS RETROFIT SOLUTIONS EVALUATION

Ryesgade 30 A-C

Ryesgade

2200

Copenhagen (Nørrebro), Denmark

Architect

Krydsrum Architects and Rönby.dk (Leif Rönby)

leif@ronby.dk

+45 6160 0699

Owner

Drost Fonden

Nørre Voldgade 88, 1358 Copenhagen

+45 3313 8580

Contact Details

Jørgen Rose

Department of the Built Environment, Aalborg University, Denmark

jro@build.aau.dk

+45 9940 2226

Other Information

Related publications
Reports in Danish

Facade of Ryesgade 30 (Source: Dorthe Krogh)

This typical residential building from the end of the 19th century, was outdated and in need for renovation. The indoor climate was poor and the energy consumption quite high. After a renovation that included new windows, thermal insulation on walls and ceiling, improved air-tightness, mechanical ventilation with heat recovery, and photovoltaic, the building achieved a 63% reduction in energy demand.

GENERAL INFORMATION RENOVATION PROCESS RETROFIT SOLUTIONS EVALUATION

Energy performance

56 kWh/m2.y

Climate Zone Cfb

Altitude 50 m a.s.l.

HDD 2906

CDD 0

Protection level Listed

Conservation Area:
No

Level of Protection:
SAVE lvl 4 - Facade can not be changed

Building age 1850-1899

Year of last renovation:
2011

Year of previous renovation:
0

Building use Residential (urban)

Secondary use:
Wholesale & Retail

Building occupancy:
Permanently occupied

Number of occupants/users:
60

Building area Net floor area [m²]: 2760,0

Building typology:
Tenement (apartments)

Number of floors:
8

Basement yes/no:
Yes

Number of heated floors:
6

Gross floor area [m²]:
3680,0

Thermal envelope area [m²]:
1260,0

Volume [m³]:
8280,0

NFA calculation method:
Danish Building Regulations

Construction type

Brick masonry wall

External finish:
Exposed brickwork

Internal finish:
Plastered (on substructure)

Roof type:
Pitched roof

+ MORE - LESS

Facade of Ryesgade 30 (Source: “Erfaringer fra prøvelejlighed Ryesgade 30C 1tv.”, DTU.BYG, Technical University of Denmark, 2011.)

Backyard of Ryesgade 30 (Source: “Bygningsfornyelse Ryesgade 30 - Totalrenovering med energi- og indeklimaoptimering + nye tagboliger”, Leif Rönby.)

Roof apartments (Source: Carsten Ingemann)

Café at ground floor (Source: “Bygningsfornyelse Ryesgade 30 - Totalrenovering med energi- og indeklimaoptimering + nye tagboliger”, Leif Rönby.)

Floor plan of apartments before renovation (Source: ”Resultater og Erfaringer fra Energirenovering af Ryesgade 30”, DTU.BYG, Technical University of Denmark, 2014.)

Floor plan of apartments after renovation (Source: Leif Rönby)

Floor plan of Ryesgade 30 A, B and C. (Source: ”Resultater og Erfaringer fra Energirenovering af Ryesgade 30”, DTU.BYG, Technical University of Denmark, 2014.)

Example showing the horizontal cornices and strips of the building. This picture was taken after the renovation when the new roof apartments had been added. (Source: Carsten Ingemann)

Ryesgade 30. Facade before renovation (Source: “Erfaringer fra prøvelejlighed Ryesgade 30C 1tv.”, DTU.BYG, Technical University of Denmark, 2011.).

RENOVATION PROCESS

Architecture

BUILDING DESCRIPTION

The Ryesgade 30 property on Indre Nørrebro is a typical Copenhagen property from 1896 built for habitation. It is built in red and yellow bricks in six floors plus unheated basement and attic floors. The built-up area was 460 m² and the total heated area was 2760 m² divided into three entrances, 30A, 30B and 30C with 12, 10 and 10 apartments respectively and it has commercial premises on the ground floor. The building has a conservation value equivalent of class 4 in the SAVE classification system due to the time-typical but worn, facade with horizontal cornices and strips.

Urban context

Inner Nørrebro is a city district in Copenhagen. It covers an area of 1.72 km², has a population of 31,046 and a population density of 18,057 per km², making it the second most densely populated district in Copenhagen (taken from Wikipedia).

State of repair

Conditions of the envelope

Description of pre-intervention building services

The building is heated with district heating and fresh air was generally provided by natural ventilation. Toilets/bathrooms and kitchens originally had ventilation shafts (relying on the chimney effect) but most of these had been blocked or simply did not work and hence fresh air was supplied through leaks in the building envelope and open windows.

HERITAGE SIGNIFICANCE

ELEMENTS WORTHY OF PRESERVATION

The facade of the building is worthy of preservation and cannot be altered according to the classification.

Heritage Value Assesment

The building has a conservation value equivalent of class 4 in the SAVE classification system due to the time-typical but worn, facade with horizontal cornices and strips. SAVE is a compilation of "Survey of Architectural Values in the Environment" (= Mapping architectural values in the environment). The method is based on an assessment of five different conditions of a building: Architectural value Cultural-historical value Environmental value Originality Condition Each of these conditions is rated on a scale of 1-9 and summed up to a total conservation value for the building. The assessment of the conservation value is based on an overall impression of the quality and condition of the building. As a general rule, however, the architectural and cultural-historical value will weigh most. Grades 1-3 are considered a high value, 4-6 for average value and 7-9 for low value. The windows are not protected and have already been improved once by adding a layer of glass to the inside. It is however a requirement that new windows should resemble the old ones and therefore four different solutions were considered: 1. Renovate existing windows 1 + 2 layers of glass (inner part opens inward) 2. Renovate existing windows 1 + 1 layers of glass (inner part opens inward) 3 . Renovate existing windows 1 + 1 layers of glass (inner part coupled to outer part) 4. New windows 1 + 2 layers of glass (inner part coupled to outer part) Solution 4 (new windows) was chosen, since this was both the cheapest and the next best solution regarding energy. There are no heritage restrictions regarding the rest of the building, however the municipality required that roof terraces and PV-panels should not be visible from the street below.

Aim of retrofit

Renovation + Extension

Before the renovation, the building had become outdated and from the toilet/bathrooms and kitchens there was originally natural ventilation, but in most apartments the ducts were either blocked or did not work. All except one apartment had a toilet, some had a bathroom, and some had a shower in a separate room or the kitchen. Generally the indoor climate of the building was poor during cold months, e.g. condensation would occur on the inside of windows (see windows section) and draughts were difficult to avoid. The load-bearing structure consists of wooden beams and solid wall. The thickness of the facade masonry varies from 350-710mm (1½-3 stone). There was no insulation in the wall and the windows were old 1-pane ineffective windows. Overall the indoor climate was poor and the energy consumption quite high, and therefore the aim of the retrofit was to improve indoor climate and reduce energy consumption while at the same time improving the apartment facilities such as baths and kitchens. The property was therefore both renovated and modernized in the urban renewal project. The following improvements were made. General improvements: New larger kitchens (kitchen stairwells were included to increase area), New bathrooms, Renovation of facades, basement and stairwells, Replacement of all plumbing (except parts of the heating system), Attractive penthouse apartments with individual roof terraces. Energy improvements: New energy-efficient windows similar to the original ones, Internal insulation with compact insulation, 3 different solutions for mechanical ventilation with heat recovery (Entrance A: Traditional central ventilation, Entrance B: Central demand-controlled ventilation, Entrance C: Decentralized ventilation systems in the apartments), Photovoltaics, Exterior insulation of gable, Insulation under basement ceiling. Indoor climate improvements: Higher degree of air tightness of the building envelope, improvement of windows and ventilation with heat recovery.

Lessons learned

This project involved a series of tests regarding the internal insulation (measurements of temperatures, humidity etc.), different solutions for windows (replace or repair?) and tested three different mechanical ventilation systems (one for each stairway). These detailed analysis have given a lot of insight into the possibilities and restrictions regarding this particular type of building, which can be used in future projects.

Stakeholders Involvement

Public sector
Municipality of Copenhagen
Njalsgade 13, 2300 Copenhagen S, Denmark
NA@NA.NA
Tel.+45 3366 3366

Architect
Krydsrum Architects and Rönby.dk (Leif Rönby)
na
leif@ronby.dk
Tel.+45 6160 0699

Energy Consultant
Ekolab
Vestergade 48 H 2. tv., 8000 C Aarhus, Denmark
ekolab@ekolab.dk
Tel.+45 8613 2016

Other
Falkon Rådgivende Ingeniører
C. F. Richs vej 107, 4. sal, 2000 Frederiksberg, Denmark
info@falkon.dk
Tel.+45 3536 4500

Other
Consultant to the building owner: Advokaterne Arup & Hvidt
Nørre Voldgade 88
ahlaw@aruphvidt.dk
Tel.+45 3313 8580

Tools used

Was the renovation process done following a specific methodology? No

Energy calculation Yes
Hygrothermal assessment Yes
Life Cycle Analysis (LCA) None
Other None

RETROFIT SOLUTIONS

External Walls

Brick wall - facades

The walls are massive brick walls ranging from 1½ stone (350 mm) to 3 stone (710 mm) in thickness with the widest walls at the ground floor. The parapets have 1 stone (235 mm) thickness. The mean U-value before renovation was 1.40 W/m2K. The facade walls were insulated on the inside with 40 mm Aerorock (a mix of rock wool and aerogel with a thermal transmittance of 0.019 W/mK) for apartments in stairwell A and B and 40 mm Kingspan (phenolic foam) insulation (with a thermal transmittance of 0.020 W/mK) for apartments in stairwell C. In both cases the finish is gypsum boards. The U-value after renovation was approx. 0.4 W/m2K. The gable wall (fire-proofing) towards the gate, which was not protected, was insulated on the outside with 250 mm rock wool with a thermal transmittance of 0.039 W/mK. This resulted in a U-value of 0.15 W/m2K.

Adding insulation to the inside of the contruction is a conservation compatible solution since is does not change the appearance of the building facade.

U-value (pre-intervention) [W/m2K]: 1,4 W/m²K U-value (post-intervention) [W/m2K]: 0,4 W/m²K

More Details

Original wall build-up

Brick - 235-710 mm thick brick wall:
710 mm

Retrofitted wall build-up

Brick - 235-710 mm thick brick wall:
710mm

Insulation - Aerowolle:
40 mm

Other - Gypsum:
13 mm

Windows

Facade windows

The original windows were wooden frames with 1 pane of glass and a U-value of 4.20 W/m2K, however some of the original windows had had a layer of glass added on the inside to improve energy aspects and reduce draught. The new windows had 1 + 2 panes of glass. The 2-pane section has krypton gas filling and the total U-value of the windows is 0.89 W/m2K.

Due to the building's status as conservation-worthy, the renovation could not change the facade expression. However, the municipality accepted that the windows were replaced with new windows that were constructed like the old windows. The new windows were specially developed for the project with drawn glass in the outer layer of the pane to give the window the same expression and mirroring quality as the original ones from 1896. The new windows that were installed are wooden windows with switched frames 1 + 2 from Frovin Vinduer and Døre A/S.

New windows 1 + 2 seen from inside (Source: Carsten Ingemann)

New windows 1 + 2 seen from outside (Source: Carsten Ingemann)

Old window example 1 (Source: “Erfaringer fra prøvelejlighed Ryesgade 30C 1tv.”, DTU.BYG, Technical University of Denmark, 2011.)

Old window example 2 (Source: “Erfaringer fra prøvelejlighed Ryesgade 30C 1tv.”, DTU.BYG, Technical University of Denmark, 2011.)

Principle of new window/wall joint (horizontal section). Vacuum insulation in window casing and aerowolle on inside of wall (Source: “Erfaringer fra prøvelejlighed Ryesgade 30C 1tv.”, DTU.BYG, Technical University of Denmark, 2011.)

Existing window U-value Glass [W/m2K]: 5,9 New window U-value Glass[W/m2K]: 0,8 Existing window U-value Frame [W/m2K]: 1,6 New window U-value Frame [W/m2K]: 1,6

More Details

Existing window type	Double window
Existing glazing type	Single
Existing shading type	NA
Approximate installation year	1896

New window type	Double window
New glazing type	Triple
New shading type	NA
New window solar factor g [-]	0,5

Other interventions

ROOF

Part of the renovation included adding new roof apartments to the top pf the building and thereby a whole new roof was added. Before the renovation the roof had a U-value of 0.52 W/m2K and after the renovation the new roof has a U-value of 0.21 W/m2K.

The roof was not part of the protected facade and therefore no restrictions were present. New roof terraces and PV panels are not visible from the street below.

Access to the roof terrace. (Source: Carsten Ingemann)

Roof terrace and skylights. (Source: Carsten Ingemann)

Roof terrace with benches. (Source: Carsten Ingemann)

New roof and roof apartments. (Source: Carsten Ingemann)

U-value (pre-intervention) [W/m2K] 0,52 U-value (post-intervention) [W/m2K] 0,15

More Details

Original roof build-up

Slate - Original roof with low degree of insulation:
12 mm

Other - Wood:
50 mm

Retrofitted roof build-up

Metal sheets - Metal sheeting :
2 mm

Other - Insulation:
200 mm

HVAC

VENTILATION

Before the renovation the building had natural ventilation through open windows and leaks in the thermal envelope. Original ventilation shafts in toilets/bathrooms and kitchens were either blocked or did not work as intended. The renovation included three different types of mechanical ventilation, one for each entrance/stairwell (A, B and C). The purpose was to test different solutions in order for future projects to have a better understanding of which solutions would fit where. Stairwell A: Traditional central mechanical ventilation with heat recovery. Stairwell B: Central demand controlled mechanical ventilation with heat recovery. Stairwell C: Decentral mechanical ventilation with heat recovery. See documentation for further details.

All ducts and ventilation units are integrated and does not alter the parts of the building that needed preservation and therefore the solution is 100% conservation compatible.

Detailed description of the three ventilation systems.

More Details

Original roof build-up	New ventilation system
Type ventilation system	Centralized
Type flow regime	Cascade
Heat recovery	Yes
Humitidy recovery	No
Nominal power	1,5 kW
Electric power	1,0 kW
Control system	Supply constant air flow of 140 m3/h. Exhaust air volumen depends on humidity levels and whether the cooker hood is in use.

RENEWABLE ENERGY SYSTEMS

Photovoltaic

80 m2 photovoltaics were added to the roof. The producer has calculated the expected production to 8,950 kWh per year and during the first year after renovation the system produced 11,000 kWh. The electricity production should cover most of the electricity used for mechanical ventilation in the apartments.

The photovoltaic system is placed on the roof and therefore did not influence the protected facade of the building.

The photovoltaic panels are placed on the roof (not integrated), but on a part of the roof that is not visible from the street.

Photovoltaics on the roof of the building. (Source: “Bygningsfornyelse Ryesgade 30 - Totalrenovering med energi- og indeklimaoptimering + nye tagboliger”, Leif Rönby)

More Details

	Photovoltaic System
Type	Monocrystaline
Collector area	80,0 m²
Total nominal power	10,0 kW
Elevation angle	30,0
Azimuth	135,0
Overall yearly production	8950,0 kWh
Heating contribuition	0,0 kW
DHW contribuition	0,0 kW
Cooling contribuition	0,0 kW
Lighting contribuition	0,0 kW

Energy Efficiency

Energy Performance

Energy performance certificate: No
Voluntary certificates: No

Energy Use

Heating
Consumption_estimation_Calculation_method: Steady state simulation (e.g. EPC, PHPP)
Consumption_estimation_Before: 152 kWh/m2.y
Consumption_estimation_After: 56 kWh/m2.y

Primary Energy
Consumption_estimation_Calculation_method: NA
Consumption_estimation_Including_DHW: No

Measured Parameters

Internal Climate
Type_of_monitoring: Punctual
Description: The heating consumption (space heating and domestic hot water) was measured before and after the renovation. Before the renovation the consumption was 155 kWh/m2 per year and after the renovation it was 83 kWh/m2 per year. Compared to calculations the measured consumption matches well for the before-situation but not for the after-situation. This was primarily due to the fact that tenants had a higher indoor temperature than assumed (22-23 C instead of 20 C) and that the efficiency of the heat recovery in ventilation systems was lower than expected. This also means that instead of heating energy savings of 63% the actual savings are around 53% - this is due to the so-called "rebound effect" where tenants "invest" some of the energy savings in an improvement of the indoor climate.

Internal Climate

Temperature

Indoor Air Quality

Daylight

Acoustic Comfort

Artifact Conservation

Costs

Financial Aspects

Running Costs

Lifecycle cost
No