WP 2.1a – D2 – part 1 Innovative Solar Air Systems - Final … · 2017-06-19 · 6642...

513479

Energy in Minds!

Integrated Project

Priority 6.1.3 Concerto

WP 2.1a – D2 – part 1

Innovative Solar Air Systems - Final Research report Solar air systems in multifamily houses

Energy in Minds is a project of the CONCERTO initiative co-funded by the European Commission within the Sixth Framework Programme.

Due date of deliverable: Month 46 Actual submission date: Month 50

2242 Deliverable No. WP 2.1a-D2 – part 1 Innovative Solar Air Systems - Final Research Report

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is co-funded by the European Commission

Start date of project: 30/05/2005 Duration: 60

Organisation name of lead contractor for this deliverable: FABO

Revision: 1

Project co-funded by the European Commission within the Sixth Framework Programme (2002-2006) Dissemination Level

PU Public x PP Restricted to other programme participants (including the Commission Services) RE Restricted to a group specified by the consortium (including the Commission Services) CO Confidential, only for members of the consortium (including the Commission Services)

Work package: WP 2.1a R/I Innovative solar Air Systems – Final Research Report

Deliverable no: WP 2.1a – D2 part 1

Due Date: 22

Participants ID

WP-leader: 3 AEE

Participants: 12 C-Falk

14 FABO

Introduction This report comprises the first part of the research report: Innovative Solar Air systems. Project leader: Mr. Ingemar Bengtsson, Falkenberg Bostads AB (FABO), Research leader: Mr Christer Nordtröm, Christer Nordström Arkitektkontor AB (CNA)


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Deliverable result Falkenberg

Contents Introduction Project description Project goals Methology Involved parties and actors Design and building process Demonstration project Växthuset multifamily dwellings Design considerations System selection considerations Simulation - Trombe wall System design – Trombe wall Function description – Trombe wall System design – Solarwall Building instructions Final system layout Construction work Buildings completed Reusults


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Introduction The project is an integral part of the Concerto initiative, Energy in minds group, cooperation between four European cities;

City of Neckarsulm, Germany City of Zlin, Czeck Republic Energy Region Weiss-Gleisdorf, Austria City of Falkenberg, Sweden

The Energy in Minds group are committed to be demonstration cities, showing how European cities and regions can change their energy policy towards energy reduction and introduction of renewable energy within their energy production systems. The work is performed with support from the European Commission. Within the initiative, each partner will perform a number of policies and demonstration project, illustrating innovative ways to reduce the energy consumption and increase the use of renewable energy for heating and cooling of buildings.

Project description The work is organised in work packages (WP), each package representing a specific technology. The work package WP 2.1 comprises the research and demonstration of solar heating systems for buildings. Within WP 2.1 a, specific research regarding Innovative Solar Air Systems will be performed. The research has been applied and realised in one demonstration project;

The Växthuset multifamily dwelling project in Falkenberg - the building of 2 new 8-storey apartment houses with low energy consumption

This report is also coordinated with a parallel report concerning solar heating systems for multifamily houses. The research results have been applied in a demonstration project;

The Vessigerbro Gymnsastics hall - the renovation of a large building used for sports and gymnastics in the city of Vessigebro, within the municipality of Falkenberg

The Fajans school – updating of energy standard of a school built in the 1970-ies in the city of Falkenberg


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Project goals The goal of the work package is to study and demonstrate how solar air systems can be successfully integrated in these building projects;

Perform study of integration of solar air system in buildings Description and typology of system types Criteria for selection of system types Criteria for architectural/building integration Criteria for technical integration Preliminary design and system layout for the demonstration projects Detailed design Building manuals Follow up on building of demonstration projects Monitoring of demonstration projects Evaluation Final research report

Methology The research will be performed through general studies of solar air systems in combination with system design and detailed design related to the three demonstration projects.

Involved parties and actors The project leader is Mr Ingemar Bengtsson of The Falkenberg Public Housing Company of Falkenberg, FABO. Mr Bengtsson holds the position as responsible for energy, heating and ventilation within the housing company. Mr Bengtsson will also conduct the monitoring of the demonstration projects. The research and design work including the reporting activities will be performed by Christer Nordstrom Architects, CNA, Mr. Christer Nordstöm being the responsible research and design leader for the integration of solar air systems of the demonstration projects. CNA will function as subcontractors under FABO. The Falkenberg-Växthuset project was designed in cooperation with the architect of the building, FFNS SWECO Architects, Mr. Staffan Premmert and Mr. Lennart Lindell. The design process also includes the client, consultants, specialists and entrepreneurs involved in the building and rebuilding project.


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Design and building process As the first step in the design process, a preliminary system design including the first system layout is carried out based on a first selection of system type. The selection of system type follows the typology presented in “Solar Air Systems – A Design Handbook”, that was elaborated during IEA Annex 19. One or several options are selected for the demonstration building and feasibility studies are carried out for the different types. These options are evaluated from different criteria;

Architectural and building integration System integration and coordination with the buildings technical systems Operation modes Preliminary energy simulation (calculation) Economy

Before the final selection, the feasibility studies are presented and the different options are discussed by involved parties, followed by the final system layout. The final step in the process is the production of the detailed design drawings and building instruction/documents are produced in close cooperation with the builder and the client. The building activities are closely followed and documented by the research team. Upcoming problems that may arise during the building process are solved through cooperation between researcher/designer and builder. Monitoring is planned during the design process and start as soon as the building is completed. The monitoring will go on for a full year before the final evaluation of the project.


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Demonstration project - Växthuset multifamily dwellings

The project comprises the integration of solar air heating systems in four 8-storey buildings with four flats on each storey. Two of the buildings are completed and the remaining two are under construction. Each building is planned with two “living areas” comprising two apartments. The living areas are separated by a staircase that runs through the building. The staircase is not to be heated by the buildings aux. heating system.

Design considerations


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Intention with solar system integration The intention is to design a solar air system which will keep an acceptable indoor climate in the staircase without using the auxiliary heating system. Architectural integration The system has to be integrated in the building in harmony with the buildings architecture with respect to aesthetics, view and day lighting. It has to be easy to maintain and to understand. Materials and components used should be sustainable and have a long life span. Orientation and shading The buildings are located along a street running in NE-SW direction with the entrance facades facing SSW. The front façade of the staircase has a fairly good exposure to the sun.

The pictures show the shades on April 1, at 12.00 (top and left) and 17.00 (right)


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System selection The following options have been considered and investigated:

1. Perforated unglazed solar air collector on the south-east wall of the building 2. Perforated unglazed solar air collector on south-front wall of the staircase 3. Perforated unglazed solar air collector on the roof 4. Integrated thermal mass solar air collector (“Trombe wall”) on south façade of

staircase

1. Perforated unglazed solar air collector on the south-east wall of the building

The picture illustrates the situation at 11.30 The system comprises a perforated solar air collector (“Solar wall”) placed on the south-east wall of the building. Solar preheated fresh air will be forced into the building with fans and used for the heating of the staircase. Considerations: The system has the following advantages:

Quite cost effective The solar collector will have no impact on the design of the staircase View from the staircase overlooking the ocean will not be affected

The system will have the following disadvantages:

The location on the south-east wall give quite limited access to the sun – especially during the afternoon

The solar collector will affect the view and shade sunlight the access to sunlight for the apartments located in the east side of the building

The ductwork between the solar collector and the staircase is difficult to integrate since the ducts will be going through one apartment.

Risk for overheating during summer since the solar heated air will enter the staircase directly


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2. Perforated unglazed solar air collector on south-front wall of the staircase

The picture illustrates the building and the solar collector from south A perforated solar air collector (type:”Solarwall”) is placed in front of the staircase facing south. Considerations: The system has the following advantages:

Quite cost effective The connection for the solar air system between the solar collector and the staircase

is easy to integrate since the solar collector is located in direct connection to the staircase

Good solar access Good technical and architectural integration


View from the staircase overlooking the ocean will be affected Day lighting of the staircase will be affected.


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3. Perforated unglazed solar air collector on the roof

Yet another option is to place the solar air collectors on the flat roof of the building as shown in the picture above Considerations: The system has the following advantages:

Good solar access – no shading elements Easy connection between the solar air system and the staircase is easy to integrate

since the solar collector is located in direct connection to the staircase Acceptable architecture View from the staircase overlooking the ocean will not be affected Day lighting of the staircase will not be affected


Decreased economy due to poor integration with the building Risk for overheating during summer since the solar heated air will enter the staircase

directly Risk for construction damage during storms from south-west which are frequent in

this region. The buildings are exposed to such winds.


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4. Integrated thermal mass solar air collector (“Trombe wall”) on south façade of staircase

The system consists of a thermal mass wall located between the glass façade and the staircase. Air is circulated with natural circulation (Thermosiphone effect) through openings leading from the staircase and the airspace between Trombe wall and glass façade. Heat is stored in the thermal mass and even the temperatures between day and night. Considerations: The system has the following advantages:

Good solar access Good architectural and technical integration. Easy maintenance. Sustainable solution with long life Reduces the risk for overheating during summer Good potential for double exploitation of building materials


Has to be heavily integrated in the building Some reduction of the view

Feasibility studies Two of the proposed solutions have been selected for the final decision and investigated more in detail:

System type 3: Perforated unglazed solar air collector on south-front wall of the staircase

System type 5: Integrated thermal mass solar air collector (“Trombe wall”) on south façade of staircase

Performance predictions The trombewall solution has been simulated using a dynamic simulation tool. It has not been possible to make advanced dynamic simulations of the unglazed solar air collector due to the lack of simulation tools. Therefore, the performance predictions are based on estimations and experience of similar applications. Such simulations point at an average solar gain of 300 kWh/m2,K per m2 solar collector.


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Simulation of Trombe wall Preliminary simulations of temperatures for different options Dynamic energy and temperature simulations have been performed of a 2 storey section of the staircase. The DEROB software, developed by the technical University of Lund (LTH) , department of building and energy design, was used. Building-model

The building model (above) represents a 2-storey section of the staircase. The screens represent the shading parts of the living parts of the building. Explanations: O East oriented surfaces V West oriented surfaces N North oriented walls G Floors T Ceilings M Trombe wall, separating glass areas S South oriented surfaces Screen Shading surfaces The model was separated in 2 volumes: Volume 1 The volume between south facing glass surface and Trombe wall Volume 2 The volume behind the Trombe wall – representing the actual staircase


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The following standards were used of surrounding surfaces: Surrounding walls, floors and ceiling: 50 mm concrete facing the room with 400 mm if

insulation on the outside Glass (external): 2-pane argon filled low-E glass, U= 1,2 W/m2,K Glass (internal): 2 pane double glass, U= 2,88 W/m2,K Trombe wall: 350 mm solid concrete

Preliminary simulation - solid wall (staircase with no windows) – Trombe wall The simulation was made using the following situation:

For the base case was assumed a totally dark staircase surrounded by insulated walls with internal thermal mass

Trombe wall case as described above. No windows were used in the northern façade No air exchange was used in the first simulations

Result As shown in the graph above, the Trombe wall will give significantly higher indoor temperatures than the “dark” staircase due to solar heating. Since the model at this stage does not include any air exchange, some overheating is noticed during summer. However, the Trombe wall system will be used for enhanced ventilation during summer which will solve this problem. Further simulations will be performed including summer ventilation. Preliminary simulation – Trombe wall– no Trombe wall


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The simulation was perform in order to compare a glass façade without thermal mass wall and with Trombe wall and do decide the effect of the Trombe wall.

Result The simulation shows that the Trombe wall will have a “moderating effect” of the temperature:

Overheating will decrease during summer Temperature variations over the day/night will be significantly lower leading to

improved indoor climate Lowest Indoor temperatures during winter will be improved (higher) due to thermal

storage. Summary – preliminary simulations The preliminary simulations show that the solution will provide an acceptable indoor climate in the staircase. The indoor temperatures will be between 10 and 25 degrees most time of the year. Overheating during summer is assumed to be avoided using the air space/volume between the Trombe wall and south facing glass wall for active stack ventilation. There will be temperatures below 10 degrees for a limited time during winter, but the indoor temperature will never be lower than +4 degrees, even at outdoor temperatures of – 15 degrees. The integration of the thermal mass Trombe wall between the glass façade and the staircase result in reduced temperature fluctuations and reduced risk for overheating.


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System design – Trombe wall

The Trombe wall is built of solid concrete as shown in the drawing above. Simulations have been performed in order to evaluate different options concerning the material of the wall:

Solid concrete wall Solid concrete wall covered with bricks Hollow brick wall

The simulations showed that the solid concrete wall will provide the preferable temperatures during day/night. There are two 250 mm ducts inside the Trombe wall going from the ground floor to the top floor. The intention is to distribute surplus heat from the top floor to the ground floor during spring/autumn. The drawing above shows the plan of the entrance floor where the air space/volume between the glass façade and the Trombe wall is decreased to give room for the entrance door. The drawing below shows the plan layout for the Trombe wall in the different plans of the staircase. The separating glass wall between the Trombe wall and the apartment walls are covered by ordinary 2-layer glass (U=2,88 W/m2,K) For architectural and “view” reasons, openings are made within the walls. These openings are covered by the same glass. The system is divided in 2-storey sections, including a half-intermediate concrete floor. The airspace between the glass façade and the Trombe wall is open through the sections with a free air flow passing the intermediate floor. At the intermediate floor, a metal grid is installed for maintenance reasons (plan 2,6,and 4). The grid is open for air flow.


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This drawing shows sections of the system: Section A Through the entrance door – left section Section B Trough the middle of the Trombe wall Section C Through the glass at the right of the Trombe wall Section norrvägg Section of the north wall of the staircase One Trombe wall section comprises the two floors 1+2, 3+4, 5+6, 7+8


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The drawing above shows an elevation of the glass façade and the Trombe wall including motorised open able windows for exhaust of used air during summer. In the Trombe wall section, metal grids are installed for air flow from the staircase to the airspace outside the Trombe wall.


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Function description The drawing above shows the function of the system: Winter mode: Air enters the airspace through a grid (GLR-1) at floor level and is heated in the airspace between the glass and the Trombe wall. The solar heated air raises and goes back to the staircase through a motorised window MIF-1. The circulation is run by natural thermosiphone effect. Surplus heat in the top of the staircase is forced down to entrance level through two ducts in the Trombe wall. Summer mode: The air in the staircase is evacuated through the airspace through the grid GLR-1 and then to the outdoor through a motorised window MUF-1. The window between the staircase and the airspace MIF-1 is kept close. The evacuated air is replaced by cool outside air through motorised windows at the north side of the airspace. The system is controlled and monitored from the housing company’s central control system.


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System design – Perforated unglazed solar air collector – “Solarwall” The perforated, unglazed solar air heating system consists of the following parts:

Solar absorber – perforated tappets-corrugated steel sheet with a selective coating Z – and U bars of steel used for holding the solar absorber at the same time function

as manifold for the distribution of air. Profile filler strips used to seal the solar absorber and to make it air-tight Panels made of cement boards used to build the air tight box behind the collector Ventilation ducts to connect the collector to the buildings ventilation system Fans (if not connected to the buildings ventilation system) Control system (if not connected to the buildings ventilation system)

The function of the solar air heating system is as follows:

Fresh outdoor air enters the solar collector through perforation (small holes) in the absorber plates. Selective surface of the Solarwall plates give a high solar absorption and the heat is transferred to the air.

The air is drawn into the collector due to a under pressure that is created in the air-tight box behind the collector.

The solar heated air is drawn into the building by fans. The solar heated air is either distributed to the building directly or through the

buildings ventilation system. In this project, the solar collector absorber is design with an angel in order to orient to the south and to give the collector an interesting design from an architectural point of view.

The illustration above shows the section of the solar collector including absorber and air.box. In this case a curved shape of the collector is shown. This was later changed to a straight collector (no curve) due to economic and functional reasons.


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To the left, you can see an early elevation/layout of the collector showing the interior of the air boxes. The air box behind the absorber is divided in 3 vertical air-tight sections. Each of the sections has it’s own air duct to evacuate solar-heated air. The reason for doing so is to avoid that the evacuation of air will be higher at the top of the solar collector. By dividing the collector into smaller sections, there will be an even air flow through the total absorber resulting in increased efficiency.


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Building instructions of the perforated solar collector

The illustration above left shows the floors of the staircase. On every second floor. There is an opening to the floor below. Between each floor, the wooden frame for the back of the collector is built (above-right)

The back side of the collector is insulated and covered with cement boards (above)


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The sides of the solar collector are carefully insulated and covered with cement boards. The connections between the sides and back are sealed for air-tightness. The solar collector can either be built in sections for each wall or as one big box. These illustration show the first case – one section for each floor.


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The picture shows the build up of the solar collector before mounting of the perforated absorber panels. You can see the three vertical sections, separated by air tight boards and separate air ducts leading from each section to the ground floor. At the ground floor, the air ducts are connected to the buildings ventilation system.


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Finally, the solar air collector is completed and covered with the perforated tappets corrugated absorbers which are mounted with air tight filler strips between the sections.


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Final system selection Based on the design and system considerations, the system 3 (Perforated unglazed solar air collector on south-front wall of the staircase) was decided to be the most convenient solution for the project:

The system is simple to build Acceptable costs Well integrated in the building

Final system layout

The picture above shows the layout and function of the ventilation system including the integration of the solar air heating system. The function is as follows:

1. Fresh outdoor air is drawn through the perforated solar collector 2. the solar heated fresh air is led through the air/air heat exchanger where it is further

heated by the outgoing-used air. 3. if needed, the air is heated by the aux. heating system 4. The air has now reached its final temperature and enters the apartments 5. The used air is evacuated through the heat exchanger where it is used for preheating

of the incoming air. The picture is a screen shot from the computer of the energy manager. It is possible for him to regulate and monitor the total function of the system from his work station.


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Construction work – Växthuset multifamily buildings Details concerning the solar collector, fittings, steel bars etc were carefully planned with the manufacturer of the system and with the local entrepreneur

The drawings above illustrate the sectioning of the collector (left) and details of the vertical steel bars (right)


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The building curing construction

The interior of top section of the collector


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Above: Interior of the solar collector before the absorber is being attached Below: The perforated Solarwall panels


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The final phase of the construction - Mounting of the solar wall panels


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Buildings completed December 2008

Above: two of the buildings completed – two under construction Below: The perforated solar air collector


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Details of the solar air collector


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Above: At a close look, the perforation of the absorber can be seen Below left: The solar collector seen from behind – the staircase Below right: The windows on the north side of the staircase are used for fresh air intake during summer


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In every apartment there is a control unit that allows the tenants to regulate the space heating of the flat. It also gives information about:

Indoor temperature and climate Outdoor climate Weather forecast Energy consumption and environmental footprint Safety Messages Calendar Etc..


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Above: The buildings have individual underfloor heating system in combination with heat recovery of ventilation air – which is also solar preheated by the solar collectors. The picture above is the interior of the heating distribution system of the building. Below: From his office, energy manager of Fabo, Mr. Ingemar Bengtsson, can both control. Regulate and monitor the heating of the buildings


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Results The four demonstration projects were built and monitored during one full year:

Vessigebro project 2007 – 2010 (2 years) Fajans Project 2008 – 2010 (2 years) Växthuset 1 Project 2008 – 2009 (one year) Växthuset 2 Project 2008 – 2009 (one year)

The system and monitoring results varies depending on the different applications. This report will illustrate that interesting conclusions can be made when comparing the performance of these four demonstration projects. Monitoring method All monitoring data are collected in the central energy control system of Falkenberg Housing company (FABO). The solar gain has been monitored in each system in sensors located after the exhaust fan of the collector, GT44 (temperature) and GF41 (air flow) as shown in the chart below of the Fajans project.

Data are processed by FABO and reported for each day during the monitoring period. In this report, data are presented on a monthly and yearly basis.


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Brief description and basic facts of the systems

Vessigebro project Location: Vessigebro, small community north of Falkenberg Use: Gymnastics hall, retrofit Building floor area: 2372 m2 Solar collector: Perforated, unglazed cross-flow solar air collector (Solarwall) Solar collector area: 133 m2 Collector location: south wall System integration: preheating of fresh air in a balanced heat recovery system

Fajans project Location: City of Falkenberg Use: School – retrofit Solar collector: Perforated, unglazed cross-flow solar air collector (Solarwall) Building floor area: 3374 m2 Solar collector area: 170 m2 Collector location: south east and south west walls System integration: preheating of fresh air in a balanced heat recovery system.

Växthuset 1 and 2 projects Location: City of Falkenberg Use: Two identical 8 storey new apartment buildings Solar collector: Perforated, unglazed cross-flow solar air collector (Solarwall) Building floor area: 2552 m2/building Solar collector area: 48 m2/building Collector location: south walls System integration: preheating of fresh air in a balanced heat recovery system.


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Monitoring results During one full year of monitoring the solar gains produced by the solar air collectors were as follows: Solar gains/m2 collector area, year Vessigebro 205 kWh/m2 Fajansskolan 151 Växthuset 1 195 Växthuset 2 153

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Vessigebro Fajansskolan Växthuset 1 Växthuset 2

Solar gain/m2 coll,year

The solar gains, used in the buildings, vary from 150-200 kWh/m2 collector area, which is quite normal for these kinds of systems. In more simple systems i.e. direct solar heating of factories etc. the effective solar gain will be significantly higher due to the higher degree of use of the solar heated air. In more advanced systems (like in the Falkenbeg projects) including heat recovery, the full potential full potential the solar collector is not used. In such systems solar collectors are used to preheat the incoming air before it is heated by the outgoing used air from the heat renovators. This means that the solar system will work at a lower efficiency compared to a open system where solar heated air is directly used for space heating. However, the results shows that, in spite of the lower efficiency, fairy good results have been achieved. It shows that this kind of simple solar air collectors can be useful in many kind of new buildings as well as retrofit projects. The results of the Fajans project is slightly lower that the other projects. This is probably depending on the solar collector which is divided in 2 collectors facing south-west and south-east. The Vessigebro project has a better performance due to a large solar south facing collector. This system is also the most simple of the demonstration projects


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The two new housing projects, Växthuset 1 and 2, has almost the same performance as the Vessigebro project which can be expected. The variations between the two projects can be explained by the fact that Växthuset 1 was completed before Växhuset 2. The 2 projects are exactly the same. Solar gains/m2 building floor area, year Vessigebro 11.5 kWh/m2 Fajansskolan 7.6 Växthuset 1 3.7 Växthuset 2 2.9

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Vessigebro Fajansskolan Växthuset 1 Växthuset 2

Solar gain/m2 floor area

The solar gains/m2 floor area depends of the size of the building. In the Vessigebro project, the solar collectors are used for the space pre-heating of a 1 storey building which lead to a reasonably high contribution to the space heating compared to the relatively small collectors of the 8 storey buildings of the Växthuset projects.


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Looking at the variations over the year (see chart below) it is obvious that the solar air collectors are not used during the summer months because there is no need for space heating during this period. Spring and autumn seem to be the best “solar period” for solar air collectors in Sweden. The cart below show the solar gain kWh/month (not related to the collector or floor area). The monitoring also illustrates that the use of the solar collectors during mid-winter is low.

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jan feb mars april maj juni juli aug sep oct nov dec

Fajans 2009 kWh

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Vessige 2008 kWh


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Costs The material costs for the collector was in average:

Solar wall collector panels 47 Euro/m2 Profiles,Fittings freight etc 8 Total 55 Euro/m2 collector area

The labour costs (as in fact the extra costs for material) highly depends on how the system can be integrated. If it is assumed that the labour and additional costs is the same as the material costs, the total costs will be approx 110 Euro/m2 In the Vessigebro project 205 kWh/m2 is produced each year which might give a yearly economic result of 205 x 0.1 = approx 20 Euro/m2 giving a payback time of 5.5 years. Lower degree of integration will result in a longer payback time and a high degree of integration and good planning can even improve the result. If i.e. solar wall panels can replace old façade material which has to be replaced anyway, this can result in very low costs for the system. If the system is integrated in existing ventilation systems, the costs for equipment (fans, control systems etc) can be held low.

Summary The four demonstration solar air projects in Falkenberg show that quite simple and low cost solar air collectors can be an attractive and realistic solution for space heating. The integration and planning of the system design is essential to achieve a good result at affordable costs.

WP 2.1a – D2 – part 1 Innovative Solar Air Systems - Final … · 2017-06-19 · 6642...

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Transcript of WP 2.1a – D2 – part 1 Innovative Solar Air Systems - Final … · 2017-06-19 · 6642...