The four selected buildings represent different ways of PV modules’ application within the building.

Library building in Mataro (fig.1-A.) constitutes an interesting and pretty innovatory example of integration of PV modules with double skin facade. The modules create southern external layer behind which a wall made of traditional glazed panels has been placed. There is 15 cm cavity between 2m2 semitransparent modules and the inner glazing.

In turn, the office-laboratory building „ECN-ЗГ in Petten (fig.1-B.) features a totally different way of PV modules’ application and type. These modules has been mainly set up as a „shadowvoltaic system”. They are shaped as external lamellas laminated with PV cells and put in front of the southern windows in four horizontal rows on each floor. One of
them that is located in the users’ view site is movable. The remaining rows of PV modules are fixed and inclined at an optimal angle (in the Netherlands) of 37 degrees from the horizon.

In the case of Doxford Solar Office (fig.1-C.), PV modules cover almost the whole southern curtain wall and create the largest PV solar facade in Europe at the moment. The facade consists of 400 thousand PV cells, shaped as non — and semitransparent PV modules.

In contrast to the Solar Office, Mont-Cenis Academy building (fig.1-D.), formed as a gigantic „hangar-like” structure, contains only a small "belt” of PV modules within its southern elevation. The bulk of the PV installation power is provided by roof PV modules that cover nearly whole surface of the „fifth elevation”. Both elevation and roof PV modules are translucent. Their transparency varies in different parts of the roof and is dependent on the distance between PV cells within the module (the higher condensation of the opaque PV cells, the poorer transparency of the module).

ANALYSIS OF THE INFLUENCE OF PV MODULES’ USAGE ON THE BUILDINGS’ INNER SPACE ENVIRONMENT

As mentioned in the introduction, the influence of PV modules’ usage on the buildings’ inner space environment may be evaluated in terms of thermal and visual comfort of the user.

Thermal comfort is achieved when the occupants find the temperature, heat movement, humidity air movement and heat radiation in their environment to be ideal.

Visual comfort is a broad term, but in this paper it is associated mainly with lighting issues. In this aspect, it exists when there is no impact of incorrect distribution of light density in a room, glare and shading, which make that perceptive faculties in the human brain operate with some interference. Visual comfort means also visual contact from the inside out and the outside in.

The analysis is carried out separately for each building mentioned above.

The analysis of each school was first focused on the analysis of the interior lighting conditions and of the shadow pattern for each window in order to select "critical” windows that needed shading protections to reduce heat gain due to solar radiation.

The shading analysis for every window was performed overlapping the sun charts on a photography of the surrounding made using a fish eye lens (360° angle view on the horizontal plane and 180° angle view on vertical plane).

To take the pictures the camera was located on a tripod, on an horizontal plane, facing the objective upside.

The final result was a polar view of the surrounding for each single point; using the pictures with the appropriate sun chart it was possible to calculate the influence of the surrounding to reduce solar gains.

In a second phase, all the information regarding the buildings was organised in a database that considered:

— shape and location;

— use of the building;

— year of construction;

— materials and physical properties of the envelope.

Six sample reference models with similar building technologies were selected and simulated to analyse their performances:

Model A prefabricated panels dimension 60×240 cm;

Model B prefabricated panels with a vertical size of about 400 cm;

Model C asbestos panels;

Model D prefabricated panels dimension 300×18;

Model E prefabricated panels dimension 60×360;

Model F prefabricated panels dimension 120×360.

For each one of the construction technologies different building shapes, dimensions and orientations have been selected.

Different solutions (i. e. improving U value, different shading devices) have been tested for the different buildings; for every model the energy effect of every transformation was reported in order to let the planner know the priority and effects the proposed solutions.

Experimental results are a central part of this project. Two types of prototypes have been developed: (i) The first set (Fig. 8) is used to obtain data for the numerical model, mainly the solar radiation interaction. (ii) The second set that is installed in a real building, will be used to evaluate the effect of plants on building users.

In the first set, the transimissivity of the canopy will be measured versus the incidence angles. To do so, a photographic method has been developed. The photographs are pro­jected to a plane perpendicular to the camera sensor and the zones of interest are divided into integration areas. For each integration area, the incidence angles, the surface and the transparent areas are identified. A graphic summary of this process can be seen in Fig. 9.

Acknowledgements

This work has been supported in part by the European Commission underthe Fifth Frame­work Programme, Thematic Programme: Energy, Environmentand Sustainable Develop­ment FP5-EESD, Project CRAFT-CT-2002-30033.

References

[1] D. Faggembauu, M. Costa, M. Soria, and A. Oliva. Numerical analysis of the thermal behaviour of glazed ventilated facades in mediterranean climates. part i: Development and validation of a numerical model. Solar Energy, 75(3):217-228, 2003.

[2] D. Faggembauu, M. Costa, M. Soria, and A. Oliva. Numerical analysis of the thermal behaviour of glazed ventilated facades in mediterranean climates. part ii: Applications and analysis of results. Solar Energy, 75(3):229-239, 2003.

[3] M. Lam. Design of multifunctional ventilated facades for mediterranean climates using a specific numerical simulation code. In Proceedings Sustainable Building 2002 Confer­ence, Oslo, 2002.

[4] T. Ojanen, I. Heimonen, C. Simonson, M. Soria, and D. Faggembauu. Pv-panel siding for renovation of walls. part i: Thermal perfomance and experiments in nothern climate conditions. In Proceedings EuroSun’2000 Conference, 2000.

[5] M. Soria, M. Costa, H. Schweiger, and A. Oliva. Design of multifunctional ventilated facades for mediterranean climates using a specific numerical simulation code. In Pro­ceedings EuroSun’98 Conference, Slovenia, 1998.

[6] M. Soria, D. Faggembauu, M. Costa, T. Ojanen, I. Heimonen, and C. Simonson. Pv-panel siding for renovation of walls. part ii: Numerical analysis. In Proceedings EuroSun’2000 Conference, 2000.

[7] K. Yeang. Designing the green skyscraper. Building Research and information, 26(2):122-141, 1998.

Lacasa has been developed as a so-called "Toolbox" addition to the development platform MATLAB-Simulink, which is widely used and 500,000 licenses worldwide have already been sold. Lacasa models the different components of the building according to their thermal storage capacity, using differential equations and diagrams. The building blocks of the technical installations are described, to a large extent, only by their characteristic dia­grams. According to the experience of GERTEC GmbH, this has proved to offer a very good approximation, and considerably reduces computation time. Industrial producers of heating controls use the simulation programs developed at the Solar Institute Julich, which enable the heating controls to be built based on a single chip computer.

The buildings of the Umwelt-Campus in Birkenfeld (UCB) were formerly a military hospital of the US Army in Germany, in the department of Rheinland-Pfalz. In 1993, it was decided to use these buildings to built up a modern University of Applied Sciences. The leading motivation of this university has to be "sustainability". The buildings were completely renovated and extended, consequently regarding technical standards of solar architecture, rational energy management and renewable energy supply systems.

Figure 1: Solar Architecture UCB

In October 1996, the University started with five study courses. Meanwhile, there are two environmental faculties, "Planning / Technology" and "Business Management / Law", with diploma courses in ‘Mechanical Engineering’, ‘Industrial Process Engineering’, ‘Environmental Planning’, ‘Applied Informatics’, ‘Environmental Economics and Business Management’ and ‘Business and Environmental Law’.

Two new accredited master courses (M. Sc.) start in October 2004, "Material Flow Management" in English and "Energy — and Environmental Engineering" in German", both curricula are regularly for two years to reach the degree "Master of Science".

At the present time, a considerable number of experimental and calculation and theoretical studies have been carried out, which consider heat exchange in the superinsulation both for steady heat modes [11, 16, 87-88] and for unsteady insulation system operation modes [11,93-95].

2.1. THREE APPROACHES TO HEAT INSULATION CALCULATION

The authors of the monograph [11] have conditionally systemised three fundamentally different approaches to the heat insulation calculation as homogeneous and discrete.

The homogeneous approach assumes consideration of the superinsulation as the form of a homogeneous medium having reduced thermophysical properties (heat conductivity of the medium, specific heat capacity, etc.). The heat flow in this case is determined by the Fourier equation and the effective heat conduction coefficient being its part is deemed to be dependent upon temperature. A drawback of such approach is the determination of reduced thermophysical parameters of a homogenised insulation system. In the opinion of the authors of the monograph [11], the theoretical determination of these parameters is not seemed to be feasible. These parameters are determined on the basis of experimental data, which imposes considerable limitations on their practical use and impedes the conduction of the analysis of the influence based thereon upon the heat exchange of various factors.

The discrete approach assumes consideration of the superinsulation in the form of a discrete system. In the opinion of the authors of the monograph [11], only this approach allows to use real rather than reduced thermophysical parameters of the system in question at the mathematical description of the heat exchange process.

The homogeneous-discrete approach to the calculation of heat exchange in the superinsulation is used in a number of well-known works.

All these methods of the superinsulation calculation are based on approximate heat transfer process models at the simplified consideration of processes passing in the heat insulation.

Bruno Nielsen, Henrik Sorensen

Esbensen Consulting Engineers, Vesterbrogade 124 B, DK-1620 Copenhagen V, DK
tel.: +45 33 26 73 08, fax: +45 33 26 73 01, b. nielsen@esbensen. dk, www. esbensen. dk

Rasmus Pedersen, Frans Drewniak

Henning Larsens Tegnestue, Vesterbrogade 76, DK-1620 Copenhagen V, Denmark,
tel.: +45 82 33 30 00, fax: +45 82 33 30 99, rasmus. pedersen@hlt. dk, www. hlt. dk

Abstract: The theme for the renovation of Albertslund Library has been to create a markedly and bright library that is open to its surroundings and environment. The overall objective is to satisfy the need for the staff at the library and users in all age groups and from all social stratums. Further to have a building which is optimised in terms of indoor daylight and thermal conditions and use of natural ventilation for saving energy in terms of cooling and electricity for fan assistance and artificial light.

The innovative elements in the project are a result of co-operative work by Esbensen Consulting Engineers A/S and Henning Larsens Tegnestue. Project meetings early in the design process between the architects and engineers has resulted in a success for integration of several innovative and effective energy elements early in the design and building process, thus saving valuable time and reducing costs.

This paper will describe the different technologies used in the project and the detailed and specialised simulations carried out in the design process will be discussed with special focus on daylight. The building will be completed in spring 2004.

1. Introduction

Albertslund Library is part of "Albertslund Huset” which was finished in the beginning of the 1970s before the energy crises. It is a two-storey building that — in addition to the library — comprises municipal administration, cinema and music venue. The municipality of Albertslund decided that "Albertslund Huset” should undergo a thoroughly renovation, mostly due to mould problems and subsequent problems with the indoor climate.

A totally new building volume replaces the first floor and the old library. The new library is designed as one large and bright space that opens up towards the surroundings. The children’s section is situated in a protruding part of the south facade with a view to the tall trees, and the
reference library faces the town hall and a lake to the north through large glass panels. The renovation of Albertslund library includes the roof construction and facade and creates new possibilities for improving the indoor daylight and thermal climate conditions. Furthermore, the new library is characterised by large open spaces and high rooms, which enables the use of natural ventilation.

The continuous skylight in the characteristic serrated roof assures dispersion of daylight into the entire deep volume. Furthermore it constitutes an important element in establishing natural ventilation.

An essential demand from the building owner was to have a green building with improved indoor thermal and daylight conditions. An example of that these improvements can be achieved in a simple and cost-effective way. It was important that the engineers and architects from the very start had a close cooperative way of working and that the way improvements could be reached was indeed considered from the very beginning of the project.

The result is a building that has improved the indoor daylight and thermal climate conditions substantially with innovative design of skylights by using integrated design process from the very beginning of the project.

This paper will describe the different technologies used in the project and the detailed and specialised simulations carried out in the design process will be discussed. The building will be completed in spring 2004.

Heating systems for buildings insulated according to passive house criteria have to meet other requirements than heating systems for conventional buildings. Possible heat delivery systems are pure air heating systems (if the space heat demand for transmission and infiltration lays below 14 W/m2) as well as all kinds of water systems (radiator, floor-, and wall heating systems). The room-side temperatures of the windows and walls to the ambient are always relatively high in such well insulated buildings, which results in a good indoor climate. Nine different heating systems (space heating and domestic hot water) were described and analyzed qualitatively. One of the main results of the sociological questionnaire was, that in multi family buildings the type of the heating system is not seen as relevant as long as it works, is simple to be used, has no failures, and little maintenance costs (ref. Figure 3). Problems with the acceptance occur for not optimal planned or mounted systems (dimensioning, control, noise etc.) no matter which type of system.

Simulation of the reference plants

Besides the user behaviour additional reference conditions were defined. The room temperature for the simulations was for example set to 22.5°C according to the results of the questionnaire. The DHW demand was defined with 6 minutes values from a tool developed by Jordan and Vajen, 2001 with in average 50 l/person, d at 45°C.

Detailed energy balances were calculated for all systems. Figure 4 shows as an example the energy flows within the decentralized air/air/water heat pump of Figure 1 left. In Figure 5 the energy balances for the buildings with 3 flats and the base case for all systems are shown. There are two bars per system, one showing the heat input and the other the heat demand, which is covered by all systems.

Figure 4 Energy flow of the decentralized air/air/water heat pump (Streicher et al. 2004).

Figure 5 Energy balance — comparison of all systems (base case, 3 flats) with electricity only for HVAC system (Streicher et al. 2004).

The systems were compared according to end-use and primary energy demand, CO2- equivalent emissions, heat delivery costs (including capital costs), and their sensitivity for changing user behaviour. The primary energy demand and the CO2 equivalent emissions were calculated using data from different literature (GEMIS 4.1,2002, Neubarth, Kaltschmitt, 2000, Kaltschmitt et al., 2003). The cost data was taken from the same literature as well as offers and questionnaires in companies.

The lowest energy demand could be found for the decentralized air/air/water heat pump system with solar thermal collectors, followed by the centralized ground-coupled brine/water heat pump equally to the decentralized air/air/water heat pump system without solar thermal system. The lowest greenhouse gas emissions were found for the centralized pellets system. The lowest heat delivery cost has the centralized gas-burner system without solar plant; the highest were found for the decentralized air/air/water heat pump system with solar thermal collectors. This system includes the controlled ventilations system, which would have to be paid separately for the other systems.

The electricity demand of the building apart from the HVAC system is very relevant for the total primary energy demand. In the CEPHEUS (2001) project it was found with 3.3 W/m2 (29.0 kWh/mPa). In the passivehouse calculation tool (PHPP 1999) it is given with 2.1 W/m2 (18.4 kWh/mPa). With the data from CEPHEUS no heating systems matches the criteria of 42 kWh/mP a end-use energy demand. With the PHPP approach all heat pump systems are close to that value, the decentralized air/air/water heat pump with solar system lays with 36 kWh/m2a clearly below. As this electricity demand is not strongly
coupled to the heating system, it was skipped from the newest calculations for passive houses in Germany.

Additionally to the base case two extreme scenarios were defined (ref Table 1). For the high energy demand system (ex 1) the DHW temperature was set to 60°C, for the low heat demand scenario (ex 2) it was reduces to 30 l/person, d at 45°C. For the high heat load scenario all systems can not completely cover the heat demand. The highest mismatch between demand and delivery for this extreme scenario has the decentralized air/air/water heat pump because of its limited heating capacity (air exchange rate of 0.55, maximum air inlet temperature of 50°C).

In a last comparison two heating up tests at cold winter conditions were simulated

• 4 hour high ventilation phase (air exchange rate of 4) with heating system running (windows open)

• 15 days temperature setback to 15°C (vacation) and heating up period (Figure 7).

For this heating up tests the limited heating capacity of the air heating systems becomes visible in Figure 7. With additional electric heater in the air inlet they need about 9 days to reach the required temperature. For heating up the floor heating system of the brine/water heat pump system reacts slower than the radiators, but the cooling needs also longer.

Table 2 summarizes the relevant data or all systems.

No significant difference could be found in the heating systems for the two reference buildings.

central pellets burner without solar plant central pellets burner with solar plant central gas burner without solar plant central gas burner with solar plant

central brine-water heat pump with decentralized DHW stores small decentralized air/air/water heat pump without solar plant small decentralized air/air/water heat pump with solar plant

operative room temperature (median of room air temperature and temperature of the surrounding surfaces)

Conclusion

Generally all analyzed heating systems fulfil the user demands, therefore it cannot be said that there is a „winner". Each system has its own specifications and pros and cons and the total evaluation is depended on the type and the surrounding conditions of the building and the users. The report summarized in this paper lists all the criteria and gives the user the opportunity to make his own decision.

The full study can be downloaded from http://www. hausderzukunft. at/ or http://wt. tu-graz. ac. at/de/ag/solar/projekte. htm

This means that the main fuzzy controller, considering the measured external and internal conditions and set point values as inputs, Fig. 3. Example of a 3D surface for non-linear

determines the set point mapping between inputs and output as fuzzy model

position of the roller blind as implemented in illumination fuzzy controller. output. PID controller is of type

PID/V, which means that it executes the velocity PID algorithm, and the output value defines the dimension for which the actuator must change its current position. In our case this means the alternation of the roller blind position. The input values for PID/V are: the desired position of the roller blind, which is defined as output signal of the main fuzzy controller and the temporary measured position of the roller blind. The output signal is calculated from the current difference between the desired and the measured roller blind position. The output signal provokes the appropriate movement of the actuator, i. e. roller blind. The main illumination fuzzy logic controller has two inputs: set point inside illumination and the difference between the inside illumination and the set point illumination. A decisive factor for window geometry alternations is "illumination” fuzzy controller with proper semantic background. It is also important to set properly the other parameters in the algorithm: parameters of the PID controller, filter time constants, sampling times and priorities of the loops.

Possible illumination oscillations are in the range of 1000 to 5000 lx or even more in short time periods. Therefore, it is more difficult to achieve efficient daylight regulation than thermal regulation. The two filters realized in filter blocks are included to damp the possible too fast and frequent oscillations of the roller blind movements caused when the external solar radiation is extremely changeable. Proper setting of the filter time constants means smoother roller blind movement. We want to exclude too frequent roller blind moving, since it is annoying to the occupants.

The first step in designing the fuzzy controller is to specify the control input and output variables and the domains for these variables. Fuzzy partitions including the corresponding linguistic terms have to be specified for these domains. This means that the unit intervals are completed with membership functions (fuzzy subsets), i. e. membership degrees are assigned to numerical values. The number and the shape of the membership functions for each variable must be defined. For the purpose of the control engineering the triangular membership functions are used. In our case the Sugeno type (IDR BLOCK

Fuzzy Logic Controller Designing Tool, 1999) of the controller is used, where fuzzy partition is done only for the input domains. These fuzzy partitions and the linguistic terms associated with the fuzzy sets and subsets represent the database of our knowledge base. The next step is to define the control rules using the linguistic terms associated with the fuzzy sets as they appear in the fuzzy partitions of the domains. On the basis of the preliminary experiments and observations of the optical process in the test chamber, the set of linguistic rules is designed for the control of the roller blind positioning to maintain the desired inside illumination. Methods to design the fuzzy controller are crisp; the obtained control function is always crisp.

The first approximation of the fuzzy controller does not result in an optimal control behavior. To improve the control behavior, tuning of the fuzzy controller through iterative procedure of experiments is necessary. The changes are considered depending on how well the fuzzy controller is able to handle the process. The possible modifications are: Redefining the domains of the variables. The adjustment of fuzzy sets offers several possibilities: changing the fuzzy partitions of the domains, adding and deleting membership functions, reshaping and rearranging membership functions. For each fuzzy variable up to seven memberships functions can be included.

• Alternating the rules in the set.

• Exchanging the logic operations in some rules, i. e. choosing other logic operators.

• Adjusting the consequences of the individual rules.

The redesign is necessary, when the controlled variable (in our case inside illumination) deviates too much from the set point values. With a trial-and-error optimization of the designed fuzzy controller the control performance is improved.

Detailed energy monitoring and data analysis allow precise values for the energy balance of the building and hence gives a more realistic picture of the resulting primary energy consumption.

On average annual 25 kWh/m2 net heated floor area are used for space heating, but in one extreme case a value Qheat =2 kWh/m2 net heated floor area was measured. Ambient heat and heat recovery cover 19 kWh/mP net heated floor area of the annual space heating. 17 kWh/mP net heated floor area are need to cover the hot water demand. Thermal losses of pipes and storage in the building average 11 kWh/mF. Figure 6 shows the heat consumption of all monitored projects. Not all projects have heat recovery or preheated fresh air for heating the air supply.

Figure 6 Total heat consumption and heat losses in the evaluated projects (related to net heated floor area)

The primary energy consumption is calculate as the sum for the total heating consumption (space heating, hot water and heat recovery)including heat losses and electricity for pumps, fans and controls. In the demonstration projects the average of the annual primary energy (PE) demand reaches a value of 53 kWh/mF net heated floor area, in some projects a minimum PE = 13.7 kWh/mFa. The primary energy consumption for other household appliances, e. g. lighting, cooking and other have a mean value of about 70 kWh/mFa. Figure 7 reviews the primary energy for the heating and ventilation systems as well as for household appliances. Only 40 % of the primary energy in the houses is used to cover the heating and ventilation demand and 60 % the other household appliances.

The best results were obtained in the semi-detached house in Monte Carasso, CH. This house has a very low space heating demand and less heating losses. Heat is supplied by wood pellet combustion and solar thermal collectors to support the hot water production. An exhaust air ventilation system is installed in the building. Fresh air intake is preheated via an earth-to-air heat exchanger.

Important for a high efficient building is the energy ratio ep which consider the sum of space heating, heat recovery (Qheat) and hot water (Qdhw) relative to the primary energy consumption (PE).

ep = (Qheat+QDHW)/PE

primary energy

[kWh/m2a] detached Bsemidetached Arow ^apartment

140

The factor ep, the amount of net space heating and hot water consumption related primary energy demand, will be less than one, if renewable energy replace some of the needed auxiliary energy. The primary energy factor for renewable energies is assumed as zero for thermal solar energy and very low for biomass and pv. Figure 8 shows the relation between primary energy demand and the net energy consumption for heating and DHW in the analyzed buildings.

Most of the buildings which use solar energy or biomass as well as having ground heat exchangers and ventilation heat recovery have a factor of energy expenditure lower than one and are very efficient. These are the buildings for the future.