FLEXIBLE FACADE SYSTEM

Transcription

1 FLEXIBLE FACADE SYSTEM Olaf B. Jørgensen Esbensen Consulting Engineers Ltd., Vesterbrogade 124 B, DK-1620 Copenhagen V, Denmark, Tel.: , Fax.: , Henrik Suhr Plan 1 Architects, Svanemosegårdsvej 9A, DK-1967 Frederiksberg C, Denmark Tel.: , Fax.: , hs@plan1.dk Abstract The Flexible Facades System combines ecological, energy conscious and architectural design considerations. The main element of the project is a modular constructed, flexible energy facade system, which can adapt to large variations in the aesthetic of the facade and at the same time adapt to different individual wishes as to how the use of the facade can be detailed in the individual apartments. The Flexible Facade System allows numerous combinations of solar measures. In fact, the Flexible Facade System itself is the main innovative element. In this project the implemented energy elements are: Low energy glazing in glazed balconies and sunspaces, unventilated solar mass wall with transparent insulation, ventilated solar wall for preheating ventilation air, photovoltaic panels and insulated facade panels. 1. INTRODUCTION During the last decade, the Municipality of Copenhagen has accomplished a number of substantial urban renewal projects. In 1995, the Danish Ministry of Housing and Building initiated a large development and demonstration scheme aiming at improving and demonstrating the national urban renewal activities The Projekt Renovering. It was decided to launch a common demonstration project Hedebygade to realise the visions of feasible urban ecological techniques within the framework of urban renewal in the old city quarters of Vesterbro. SBS Urban renewal was appointed as project leader for these activities. The common demonstration projects involves a number of different urban renewal activities. One of these is the development of a Flexible Facade System to be used for implementation of solar energy elements when renovating facades in the existing housing stock. The system should also be useful in new build houses. The innovative design of this Flexible Facade System has been developed by a design team consisting of Plan 1 architects (project leader), Esbensen Consulting Engineers Ltd., the Danish Technological Institute, Gilling A/S (facade contractors) and SBS Urban Renewal 2. AIM The aim of this project has been to develop a Flexible Facade System to be used for energy conscious building renovation. The system shall enable the use of a number of different solar energy elements depending on the actual orientation of and solar gain on the facade to be renovated. When renovating facades in multi storey housing in old and dense urban areas, the costs often are too high. Therefore, the development and demonstration of a flexible and inexpensive facade system will help to make future renovations of such facades more cost effective. 2.1 Main renovation reasons The Flexible Facade System helps to overcome the problems related to the main renovation reasons, namely: Degradation of facades High energy demand for space heating, ventilation, domestic hot water and electricity Poor thermal comfort General urban renewal activities 2.2 Additional benefits Besides these more technical elements also some additional benefits are achieved: Added living area Added value to the apartment. 3. CONCEPT DESCRIPTION 3.1 Concept description The main element is a modular flexible energy facade system which can adapt to large variations in the aesthetics of the facade and at the same time can adapt to different individual wishes of how to detail the facade in individual parts of the facade. The Flexible Facade System enables maximum use of solar energy combined with minimised heat losses. The facade is constructed in modules in which active as well

2 as passive solar energy gain elements may be integrated as illustrated below. The Flexible Facade system may also be used for facade protection as well as for extending the living area providing a highly insulated glazed facade for existing buildings. Figure 1 Principle of the Flexible Facade System In general, one can distinguish between two different system designs: Either by extending the living area by including or even adding a balcony to the apartment or by replacing an existing facade with an energy conscious solar facade. 4. INNOVATION The innovative design of the Flexible Facade System has been developed through an integrated design process involving all of the partners of the project group. During the concept development the following innovative aspects and elements have been prioritised and analysed: 4.1 Innovative aspects A Flexible Facade System for combination of a variety of solar technologies. Moderate increase of the costs compared to standard systems when using only one solar element. For combinations of a number of solar technologies the building costs are expected to be reduced compared to standard systems. Reduced design overhead by using a predefined system. 4.2 Innovative elements The Flexible Facade System allows numerous combinations of solar measures. In fact, the Flexible Facade System itself is the main innovative element. In this specific demonstration project the implemented energy elements are: Low energy glazing in glazed balconies and sunspaces. Low energy glazing is used to diminish the heat loss from the glazed balcony and the apartment behind it. Ventilated solar wall. In facades with large solar incidence, ventilated solar walls are used to preheat ventilation air. The ventilated solar walls are placed in the facades and in the parapets in the staircases. Unventilated solar mass walls with transparent insulation have been used on massive solar exposured house ends (brick work). Photovoltaic panels for production of electricity are integrated in both facades of the building. The panels are placed with orientation to the South and inclinations of 90. Insulated facade panels. On parts of the facades oriented to the North, thermally insulated panels reducing the heat losses are used. 4.3 Required technical improvements and critical aspects To fulfil the demands from the users (clients, tenants, authorities) the following critical aspects have been considered during the development of the Flexible Facade System: One important critical aspect is the architectural expression of the system, which must be approved by the local authorities. This is especially a problem in dense city centres when dealing with old buildings of an architecturally and historical high value. The main problem is the introduction of large glazed facade areas, which will effect the architectural expression of the area. Thus, besides respecting the existing architecture, glazing types and orientations must be selected with respect to minimising reflections of direct solar to avoid glare. Another critical technical aspect is designing the system without introducing cold bridges and still leaving the opportunity open for air inlets, piping for water based systems, cabling for PV-systems or other solar elements integrated in the Flexible Facade System. Approximately 75% of the window area (if windows are implemented) must be openable. This is partly due to fire regulations (escape routes) and partly because of wishes from the tenants of still being able to enjoy the qualities of an open balcony (if applied on balconies) during the summer period. Especially for double glazing systems this aspect is complicated and must be given special attention.

3 Also local fire regulations have to be respected. The introduction of large glazed areas in the Flexible Facade System, might include burnable materials or materials that are not yet accepted by the local fire regulations (e.g. transparent insulation) or solar air heating systems that might increase the risk of fire spreading. In general, the required technical improvements are: to respect the demands from the local authorities regarding architecture and building regulations and to design the facade system giving special attention to ensure a high flexibility of the system so that more or less any solar component might be replaced by a new or another solar element without having to change the facade system itself. Thus, a flexible facade system design has to be adjusted to the local conditions, but should be based on the main principles of this Flexible Facade System. 5. MODELLING 5.1 Model description and parameters The system is demonstrated in a multi storey building constructed around 1900 in the centre of Copenhagen in a dense urban area. This building has been used as a reference for estimating the possible energy gain from the Flexible Facade System. An overview of the site area is shown below. Site North Figure 2 Placement and orientation of the demonstration site of the Flexible Facade System in Copenhagen. Simulations of heat flows, temperature conditions, etc. have been carried out with the thermal simulation program "tsbi3". The tsbi3" program can be used for analysis and design of building elements and system components as well as a full simulation of the dynamic performance of a building under realistic use and operation. Calculation of the performance for the PV-panel is based on the solar absorptance in the solar wall from the "tsbi3" simulations and calculations made by the spreadsheet based calculation tool Ashling 1.0 Outdoor climate data from the Danish Test Reference Year, [3], have been used for the simulations. The simulations have focussed on the energy savings and energy gains from using advanced glazed balconies, ventilated solar walls, unventilated solar mass walls with transparent insulation and PV-systems. The results of the simulations are to be seen as examples of possibilities rather than optimised designs as the main element of this concept is the Flexible Facade System itself. The energy elements used in the simulations and in the demonstration projects show examples of the technologies that might be used in the Flexible Facade System. In the demonstration project, these choices are not always optimised but under the given conditions (especially building orientation and surroundings) a good impression of what might be implemented in future applications is given. Besides modelling through simulations, a 1:50 model have been made to illustrate the integration of the Flexible Facade System in a larger urban renewal project (Hedebygade-karreen, Copenhagen, Denmark). 5.2 Expected energy savings The expected annual energy savings compared to conventional renovation (facade insulation or single glazed balconies) vary between kwh/unit (apartment) depending on which solar elements that are implemented in the actual system. From the design studies the following savings are expected: Glazed balconies - 1, 200 kwh/year per apartment Ventilated solar wall - 1,000 kwh/year per apartment Unventilated solar walls with transparent insulation kwh/m² absorber PV panels facing the street - 83 kwh/m² PV panel, corresponding to 293 kwh/year per apartment PV panels facing the court yard - 57 kwh/m² PV panel, corresponding to 67 kwh/year per apartment The expected system efficiency for the PV systems is 12%. The ventilated solar walls in the staircase will increase the temperature in the staircase with between 7 and 15 C. This will diminish the risk of condensation and improve the comfort conditions.

4 6. MARKET 6.1 Building types The potential market building types are: multi storey housing, office buildings, schools, shopping centres, all with no or only little insulation. In short, buildings with large facade areas are the potential market as the system might else be to expensive 6.2 Application potential About 10 to 15% of the existing housing stock in Denmark (multi storey housing) may benefit from this technology. The major part of the building stock being renovated is old multi storey housing. It is estimated that up to about 10% of the housings being renovated (~ apartments per year), technically, and from an energy saving point of view, might benefit from the use of the Flexible Facade System. Besides, there is a large export potential for the developed Flexible Facade System. The facade manufacturer (Gilling A/S) has defined this potential as covering a geographical area from Sweden to France/Italy and Eastern Europe. Actions in the export market may be handled by the manufacturer or by co-operation with local manufacturers. One example of export activities is that specific actions and market confirmations have already been made in co-operation with the building department on the Danish embassy in Germany. The construction costs were higher than predicted. The reason for this is that the contractors involved in the building project see the project as a conventional project rather than an R&D project. Thus, the demonstration is not seen as an object of investment like it was for the original contractor involved in the design phase. 7. APPLICATION EXAMPLES The Flexible Facade System or earlier versions of some of the main elements of the system re demonstrated in three projects The Yellow House, Østerbo and Flexible Facades. The Yellow House and Østerbo are described in detail in a separate paper at the Eurosun 2000 conference. 7.1 Flexible Facades The Flexible Facade System is currently being implemented in an urban renewal project, Copenhagen, DK. This project will be completed in summer Thus, the Flexible Facade System will most likely be part of the technical tour about Solar Architecture to attractive solar buildings in Copenhagen in connection to the Eurosun 2000 conference. Below is shown drawings of different uses of the flexible facade system. 6.3 Cost target The cost target for the building costs for the innovative part of the complete renovation was 194,400.- EURO. From the tendering, the total cost for the innovative part of the demonstration project is calculated as 216,750.- EURO. This covers a facade system for 15 apartments plus 122 m² of ventilated and unventilated solar walls. For the individual parts the costs are: Glazed balconies (14) = 53,100.- EURO French doors (3) = 6,750.- EURO Open balconies with PV panels (26 m²) = 70,850.- EURO Ventilated solar wall for preheating ventilation air (48 m²) = 13,500.- EURO Ventilated solar wall for preheating fresh air for stair case (8 m²) = 7,200.- EURO Solar mass wall with transparent insulation (66m²) = 59,050.- EURO Site costs = 6,300.- EURO Total = 216,750.- EURO Figure 3 Street facade with Flexible Facade System after renovation

5 Figure 7 Vertical cross section of the Flexible Facade System with solar wall for preheating ventilation air. Figure 4 Court yard facade with the Flexible Facade System after renovation Figure 8 Horizontal cross section of the Flexible Facade System with solar wall for preheating ventilation air. Figure 5 Vertical cross section of the Flexible Facade System with solar mass wall with transparent insulation. Figure 6 Horizontal cross section of the Flexible Facade System with solar mass wall with transparent insulation. Figure 9 The Flexible Facade System and the principle of the ventilated solar wall for preheating ventilation air. The system is mounted on the South facing house end of the neighboring house.

6 7.2 Østerbo An example of the Flexible Facade System used for advanced glazed balconies is shown below. the facade design in an architecturally and technically satisfying way. The elements have been implemented almost at the estimated costs and almost without problems and delays (at least regarding the innovative parts of the project) during the construction period. The design team expects that the system will perform as predicted and look forward to the evaluation of the energy performance of the Flexible Facade System which will hopefully be completed by the end of ACKNOWLEDGEMENT This project is funded by the Danish Ministry of Housing and the Municipality of Copenhagen. SBS Urban Renewal has represented the clients and has participated in the design phase. 10. REFERENCES Projekt 002-6, Flexible Facader, Enghavevej 28 A & B - Udviklingsrapport (report about the concept development) by Plan 1 architects and Esbensen Consulting Engineers, In Danish. Urban Ecology Working Conference Catalogue on ecological systems. SBS Urban Renewal, Copenhagen, Denmark, Figure 10 Example of the Flexible Facade System used for an advanced glazed balcony in Østerbo, Vejle, DK. Photo: Plan 1 Architects. 8. CONCLUSION From the development of the Flexible Facade System it can be concluded that such developments are certainly very challenging and also very time consuming. However, when the right circumstances are present it is definitely possible to develop a system which enables the combination of a number of solar measures to be used in one facade system. Johnsen K., Grau K. (1994). tsbi3, Users Manual. Danish Building Research Institute, Copenhagen. O Sullivan L (1994). Ashling 1.0 Manual. National Microelectronics Research Centre, University College Cork Ireland. Andersen B., Eidorff S., Hallgren L., Lund H., Pedersen E., Rosenørn S., Valbjørn O. (1982) Vejrdata for VVS og Energi. Dansk referenceår TRY. SBI-rapport 135, Statens Byggeforskningsinstitut. English summary. Jørgensen O. B., Hendriksen O. J. (2000). Glazed Balconies and Sun Spaces Energy Savers Or Energy Wasters?. Eurosun 2000, Copenhagen, Denmark. In the ongoing demonstration project it has been possible to implement five basically different energy elements in