Measurement serve the purpose of giving a qualitative understanding of how specific design features in an existing building respond to outdoor environment. Initially the precise measurement of the outdoor variables (Solar radiation, Wind Velocity and direction, Air temperature and R. H) and the resulting indoor conditions (Air temperature, M. R.T., Air Velocity and R. H.) are required over a period which should be two of three times the time taken by the building to respond to the external conditions.

Rather than attempting detailed measurements of one building, we thought it would be more fruitful to take limited measurement in all the different building types with the specific purpose of obtaining an overall view of the Indoor thermal environment in each case and to try to relate it to a standard outdoor environment (such as at meteorological observatory) instead of highly variable micro climate around the building Measurement of this type can;

i. Show the thermal behaviour of specific building elements.

ii. Provide a basis for comparing the Indoor thermal conditions existing in different areas of building.

iii. Provide a basis for comparing the overall performance of different buildings.

Experimental set up

For conducting the experiments two historical residential buildings were selected, one compactly planned and the other courtyard type, irrespective of their floor area but of same building form.

Experiments were conducted in the peak seasons in two buildings in the first week of January 1998 and last week of May 1998.

The experimental set-up was created by fixing up the Thermocouples on both the sides four walls of North, East, South, West oriented rooms in each building.

Parameters measured and the corresponding instruments used :

Climatic Parameters

Instruments used

SHAPE * MERGEFORMAT

Analysis Of The Data

The measured data was fed into the computer and the Graphs were plotted. The Graphs were then analysed on the basis of the following parameters:

* Air Temperatures

* Air Velocity

* Relative Humidity

* Time Lag

* Thermal Comfort Index (T. S.I.)

BUILDING II —( Jannat — Ki — Khirki — Fig, 3)

Conclusion

The fact is that in heritage buildings some very ingenious solutions can be seen, to the architectural problems of resisting the weather and of maintaining comfortable conditions indoors when the climate is harsh outside. By necessity these solutions have worked with simple materials and through the manipulation of geometry of building form, through the relationship of one building to another so as to provide shading, windbreaks, control of cooling breezes and so on as well as through the relationship of buildings to topography,
and by the use of trees and plants. The result is an infinitely more subtle, economical, humane mode of design, one that is often formally and aesthetically very rich as a consequence; by contrast with the brute force technological solutions of today which work inspite of climate, rather than working with the elements, and which rely on ‘imported’ energy and mechanical services, rather than using local natural forces, deflected or diverted to achieve the facts desired.

The results of the experiments show that:

1. The thermal performance of the Building — I is found to be the most comfortable out of both the case studies. In this type of building, the amplitude of indoor air temperature was no more than 5-60C while the outdoor temperature fluctuation was of the order of 180C. The maximum indoor temperature was 8 0 C lower in summer and 3 -4 0C higher in winter than outdoor maximum.

2. Ventilation apertures which were kept open throughout the day caused the building to warm up during the day but the air movement provided greater thermal comfort.

3. A time lag 6 — 8 hours was observed in the historical buildings. The greater time lag is also accompanied by a smaller decrement factor, which reduces the heat flux entering the building.

4. The courtyard system ensured ventilation through the building even during the periods when the outdoor conditions were calm, provided the building temperature at such times was higher than the outdoor temperature and ventilation was desirable.

5. The areas of the building directly exposed to the sun reached temperature which were at times 150C higher than the corresponding ambient air temperature. The control of solar radiation in this type of climate is therefore paramount.

6. Orientation and layout played and important role in reducing energy load on heating and cooling appliances and allow maximum use of sun light for lighting purposes and minimum use of artificial heating and cooling

7. The heat storage capacity of thick walls and roofs tends to narrow the internal range tending to bring it to a level fairly close to the average external temp.

8. Form of the enclosure should be with minimum surface area exposed to solar radiation. Here the buildings were square in shape which not only reduces heat gains in summer but at the same time minimises heat loss in winters.

9. Vegetation cover to a building acts as a beautiful natural self regulatory system and thus improves performance of a passive system.

10. Use of building elements such as shading devices, buffer spaces like Courts, verandah etc. wind catchers screens, recessed openings, water Body, vegetation at appropriate places helps considerably in tempering the stress of the climate.

References

Books

1. Aronium J. E, Climate and Architecture, Reinhold publishing Corp. New York.

2. Givoni B, Man, Climate and Architecture. Applied Science Publishers London, UK, 1976.

3. Jarmul Seymour, The Architecture Guide to Energy Conservation Mc Graw Hill Book Comp. New York 1980.

4. Koenigsberger and others, Manual of tropical housing and building (Part I) : ClimaticDesign, Longman Press India 1975.

5. Kukreja C. P. Tropical Architecture, Tata Mc Graw Hill Publishing Company Ltd. New Delhi 1978.

6. Martin Evans, Housing Climate and Comfort, Architectural Press LTD, UK, 1980.

8. Olgay Victor, Design with Climate, Princeton University press, USA 1973.

9. Wagner W. F. Energy Efficient Buildings, Mc Graw Hill publishing Comp. New York1980.

10. Watson Donald, Climatic Design Mc Graw Hill Company new York 1983.

Journals/papers

1. Bhatia Gautam, The Architecture of Laurie baker, Inside Outside Oct./Nov. 1989.

2. Gandhi Nandini, Power Hungry : Switch to renewable energy resources, Indian Architect and Builder, April 1991

3. Gupta Vinod, Energy Conservation Indian myths and realities, Architecture + Design Vol. IX, No. 3 May June 1992.

4. Krishan Arvind, Agnihotri M. R. Bio-Climatic Architecture a fundamental approach to design, Architecture + Design Vol IX No 3 May June 1992.

5. Prakash Sanjay, Energy Conscious Architecture : an endless quest Architecture + Design Vol. IX No 3 May June 1992.

Stephan Vidi, Martin Meier, Andreas Beck, Jochen Fricke

Bavarian Center for Applied Energy Research (ZAE Bayern)

Division Thermal Insulation and Heat Transfer Wurzburg, Germany

In this paper we present a daylighting system based on simple glass cylinders. The system separates the direct and diffuse radiation via its geometry, blocking out the former while being highly translucent to the latter.

This enables a room to be illuminated without glare problems and also reduces overheating.

Introduction

A visually appealing office has a positive influence on the well-being of the people working in it. One of the most important factors involved here is daylight. Daylighting elements should aim to reduce glare and have some degree of transparency.

This can be achieved by producing light-redirecting elements which shut out the direct sunlight while leaving the diffuse light unaffected. In this way, glare problems are largely avoided and the room has sufficient lighting.

Conventional light-redirecting elements are based on prismatic foils [1] or plates, special reflectors and profiles or graphic films. These systems are either difficult and expensive to build or are not suitable for being integrated into insulated glazings.

In this paper we present a daylighting system based on simple glass cylinders, which shuts out the direct sunlight while being highly transparent to diffuse sunlight.

Thermal comfort conditions are provided by a primary air (distributed by means of a displacement ventilation system) + radiant ceiling system. This combination minimises electricity consumption in pumps and fans. Light weight radiant ceilings allow for lower air temperature in winter and higher in summer, thus reducing energy consumption; moreover, the presence sensors, coupled with CO2 sensors, can modulate either the air flow and the ceiling temperature when few or no people are in the room, thus avoiding useless energy consumption. In summer night cooling takes place.

1.2.1 Tri-generation system

Gas engines are the core of the energy system of the building. They are connected to electric generators to produce most of the electricity required. The engines waste heat is used for heating in winter, for cooling — by means of absorption chillers — in summer and for hot water production all year round. Since in China presently is not allowed to sell electricity to the grid, the system is controlled in such a way that neither the electricity production exceeds the building’s demand nor the waste heat produced exceeds the heating or cooling demand. This means that sometimes, when thermal loads are low, electricity production is not sufficient and some power has to be taken from the grid. Some other times the cooling loads — that are higher than the heating ones — are so high that too much electricity would be produced; in this case, the excess electricity is diverted to compression chillers, slightly reducing, at the same time, the power of the engines. A sophisticated, "intelligent” control system manages the plant.

Because of the cleaner electricity produced, the amount of CO2 emissions per square meter of the SIEEB will be far lower than in present Chinese commercial building stock.

S. Gschwander, P. Schossig, H.-M. Henning Fraunhofer-Institut fOr Solare Energiesysteme Heidenhofstr.2, 79110 Freiburg Tel.: 0761 /4588 5291, Fax: 0761 /4588 9000 Email: stefan. gschwander@ise. fhg. de

Abstract

Phase-Change-Slurries (PCS) are mixtures of a Phase-Change-Material (PCM) and a carrier-fluid. Such PCS of microencapsulated paraffin as PCM and water as carrier — fluid are investigated at Fraunhofer ISE. The shell of the microcapsule prevents an interaction between the paraffin and the water.

At ISE a test-facility was built to study the stability of the capsules while pumped with conventional pumps through common used heating components like pipes, heat exchangers, volume-flow measurement instruments, pressure relief valves etc. To analyze the stability of the capsules SEM-pictures are taken after pumping them sev­eral weeks to control the optical state of the capsules. The specific heat of fusion is checked by DSC-Measurements.

Thermal measurements are carried out to investigate the thermal behavior of the Slurry while pumped through heat exchangers. The results show that the PC-Material can be melted and frozen while flowing through the heat exchangers. The presented results illustrate that microencapsulated PC-Slurries can enhance the heatcapacity of a heat-carrier-fluid and they are also stable enough to be used with common heating or cooling devices.

Introduction

Phase-Change-Materials (PCM) can store heat approximately isothermical in a very small temperature bend. A suspension of microencapsulated paraffin and water is a pumpable Phase-Change-Slurry (PCS). With these kind of slurries it is possible to charge a pCm at one place with heat and to discharge it again at an other place.

At Fraunhofer ISE this kind of PCS-Fluids are studied within a European project for two years now. The aim of this project is to develop PCS, which offer a high specific heat of fusion and also the capability to be used in common pipeworks. In Japan PC-Slurries, espe­cially Ice-Slurries, are already in use, particularly in the sector of building climatisation. With Ice-Slurries the phase transition from water to ice or reverse is used to store high quantities of heat. Ice-Slurries are suspensions of water and ice-particles, additives prevent the aggre­gation of ice in the slurry. With these kind of slurries high quantities of heat can be stored at 0°C. Temperatures below the point of freezing of water has to be reached to generate such an Ice-Slurry.

Comfortable temperatures for humans during summertime reaching from 22 to 24°C [4], so it is not very reasonable to cool down to temperatures below 0°C. Especially chillers are running with a bad efficiency at low evaporator temperatures. PCM with higher melting points could noticeable improve this situation.

These kinds of slurries could also be interesting for heating and storage applications if the melting-enthalpies are high enough. Heat exchangers would operate with smaller
temperature differences thus the heat exchange area could be minimized. Another bene­fit, compared to water in heating applications, would be the lower operating temperatures which will reduce heat losses. Lower mass-flow-rates would be possible because of the high storage density of PCS, that causes lower hydraulic performance and for that less electrical energy is necessary.

In this section the building, its analysed walls, the used measurement equipment and the test sequence are briefly presented. More details about the building and walls are included in (Porcar, 2004).

The building

The building analysed is being used as a workshop at the Plataforma Solar de Almeria (Tabernas, Almeria, Spain).

Its design includes some design strategies intending to save energy maintaining the desired comfort. The aim of these implemented features are the following:

• Overhangs size was calculated to allow solar gain into the room in winter, and to avoid it in summer.

• Windows have been diagonally placed to promote cross ventilation.

The building is being monitored to evaluate the effect of the implemented saving strategies, the degree of comfort achieved and also to validate simulation work.

This building is very useful as it allows applying sophisticated analysis tools and due to its simplicity and high degree of knowledge about its construction, it is possible to apply different approaches and to compare their results.

Analysed walls

The opaque walls of the building have been analysed. Figure 2 schematically presents these walls.

North, East and West walls are identical. South wall is also identical except that it has a wider air chamber and also a 2cm polystyrene (PS15) panel attached on the indoors surface.

Figure 2: Constructive schemes of the analysed walls.

Sensors

The following sensors have been installed:

• Four indoor and one outdoor air temperatures using PT100 four wire connected, protected from solar radiation and ventilated.

• Global horizontal and vertical solar radiation using thermoelectric pyranometers

• Heat flux density leaving the room through the ceiling, south, north and west wall using thermopile based transducers. All of them centred in each wall and embedded on its indoors surface.

• Relative humidity using capacitance transducers.

• Wind velocity sensors using optoelectronic transducers

• Wind direction using resistance based transducers

All these measurements have been read using a datalogger which A/D resolution is 16

bits.

Sensors where installed with the constraint that monitoring should not be intrusive and

taking into account that the building was being used as a workshop.

Meteorological sensors were installed near the building.

Test sequence

As it was intended to make compatible the normal use of the workshop with the measurements carried out, no tests strategy has been implemented in this case. However it is usual to use some kind of cooling or heating power to excite the system (Letherman et al, 1982).

In principle the normal use of heating and cooling devices could have been used for this purpose but due to the implemented saving strategies very low heating and cooling were required, so most of the time the building was in free evolution.

As weather conditions were the only external exciting signals available it was decided to use winter data for analysis, where these excitation signals were more powerful. So the following data were used:

Winter: Since the 20th of December 2003 to the 6th of January 2004. These data are graph in data in Figure 3 to Figure 6.

Data were read each second, and averaged and recorded each ten minutes.

Figure 6: Measured Heat Flux Density:
Ceiling and South Wall.

ir. A. B. Schaap, drs. M. J. de Bruijn, Ecofys, Kanaalweg 16-G 3526 KL Utrecht,

The Netherlands. A. Schaap@Ecofys. nl

The standard solar domestic hot water system (in the Netherlands around 3 m2 collector area and around 100 litre of storage capacity) is developing into a solar combi system with around 6 to 8 m2 of collector area and around 200 to 300 litre of storage volume. This combi system can deliver more than half of the hot water demand of an average single family house and a small part of the heating demand in winter. This system has a big surplus of energy in summer. This surplus can be used for air conditioning in combination with a sorption heat pump. In summer the solar system drives the sorption system to deliver cooling. In winter the sorption system is driven by the auxiliary burner as a heat pump to produce space heating. In this way a very high CO2 reduction can be accomplished, by using the sorption system as well as the solar system all year round. The feasibility of such a system was studied.

The natural gas boiler for space heating and hot water has reached its thermodynamic limit. The efficiency is near to 100 % of the higher heating value. The efficiency on domestic hot water is somewhat lower but this efficiency is rising rapidly.

The industry is searching for ways to overcome the 100 % barrier. There are several solutions for this challenge:

• An electrical compression heat pump.

• A combination of a natural gas boiler with a small electric heat pump.

• A natural gas (micro) combined heat and power system (internal combustion, Stirling or fuel cell)

• A natural gas driven sorption heat pump.

With these solutions the primary energy efficiency can be raised to 120 to 160 % of the higher heating value, by using the exergy of the combustion. All four solutions have their pros and cons and it is in this stage not clear which solution will dominate which part of the market. The general advantage of the sorption heat pump is that the operational costs are related to the costs of the heating fuel (natural gas, oil etc.) and hardly to the costs of electricity as the other three options are.

We are especially interested in a combination of the sorption heat pump with a solar thermal system. This can be accomplished in the following way. In summer the solar system drives the sorption system to deliver cooling (see figure 1). At the same time the solar system produces hot water with the gas boiler as auxiliary heater. The sorption system rejects heat to the ambient. In winter the sorption system is driven by the gas boiler as a heat pump to produce space heating. The sorption system extracts heat from the ambient. Hot water is produced by the solar system, by the sorption system and by the gas boiler. The solar system produces also a small part of the space heating demand. The cooling delivery system in summer can be the same system as the heating delivery system in winter. The heat rejection subsystem in summer can be the same system as the heat extraction subsystem in winter.

The aim of the study was to determine the feasibility of such a system. The market that we are aiming at is the cooling, heating and hot water demand of buildings. The buildings can be subdivided into single family houses and commercial and institutional buildings. We concentrated on the single family houses, because it is the largest market with the largest numbers of one single type of product.

The single family houses can be subdivided into existing and newly build houses and into:

• Detached houses (build apart from each other)

• Terraced houses (build in rows)

• Apartment buildings (in stacks of houses)

In the Netherlands there are about 6 million existing houses and every year about 70,000 houses are build. So with a replacement every 15 years on average, the replacement market is with approximately 400,000 units bigger than the market for newly build houses. Figures 2 and 3 give an overview of a solar sorption system in the summer and in the winter situation.

^ Y Ambient

We can see that a valve is needed to switch from summer operation (condenser delivers waste heat and evaporator delivers cooling) to the winter operation (condenser delivers heating and the evaporator extracts heat from the ambient). The heat delivery system can be the same system as the cold delivery system (for example floor/wall heating or air heating). The waste heat in summer and the source heat in winter can be delivered/extracted to/from the ambient air, or can be integrated with the ventilation system.

To be able to simulate the solar sorption system we need demand patterns of typical houses over a typical year. In The Netherlands newly build houses have to comply with an energy standard called the EPN (Energie Prestatie Normering). Of course it is allowed to build more energy efficient than the standard. In this way we came to two different typical newly build houses; a reference house build according to the energy standard and a minimum energy house in which the heating demand was reduced to the technical limits.

For the existing buildings we have also chosen two typical cases. The average house according to the Dutch national energy inquiry (BAK) and a big house with a double as high floor area, but the same construction. These four houses form a reasonable cross section of the Dutch single family housing market as a whole. The demand of existing apartment buildings will fit between the reference house and the average house. Newly build apartment buildings fit between the reference house and the minimum house.

With an Ecofys house simulation program we generated hourly values of the space heat demand for these four different single family houses.

Reference house: In 2003 newly built houses have to reach an EP (Energy Performance) value of 1.0 to obtain a building permit. The lower the EP the lower the heating demand (all other aspects equal). The NOVEm single family terraced reference house was chosen (1999 tuinkamer tussenwoning). The house is calculated with the EP calculation program and subsequently with an Ecofys house simulation program using the Test Reference Year for De Bilt to generate hourly values of the space heat demand. The house has a floor area of 111 m2 divided over two stories and an attic. It has a calculated heat demand for space heating of 10.8 GJ/year.

Minimum Energy house: This house has the same dimensions as the reference house. In this case however the heat loss of the house is reduced to the technical limits (thicker insulation and triple glazing). The calculated heat demand is only 5.8 GJ/year for space heating. In this calculation the internal heat production was lowered from 750 W (for the other three houses) to 400 W continuously, because we expect the people in such dwellings

to use energy efficient appliances. If not so the heating demand can even be as low as

1.5 GJ/year (comparable to a passive house).

Average house: This house is based on the heat demand for an average existing Dutch house (BAK 2001). The calculated space heat demand is 35 GJ/year.

Big house: This house has the same construction as the average house only the floor area is increased with a factor of two. This house was added because it can be expected that sorption systems will be first cost effective in houses with a high heat demand. The space heat demand is 64 GJ/year.

The second field of interest in the scanning sky simulator applications concerns the assessment of a specific daylighting system designed for buildings at the design stage.

The analysis is aimed at determining the most suitable solution in order to maximise the entrance of diffused skylight and meeting the daylight factor standard requirements, while screening at the same time direct component of solar light, so as to control overheating and glare phenomena. Forthis kind ofstudies, quantitative and qualitative data are collected for a larger number of conditions with the aim of reproducing to a greater extent daylight variations during the year, within an indoor environment. Consequently, the analysis protocol is based on the simulation of different sky condition (clear, overcast, intermediate), periods of the year (December, March and June) and hours of a single day (from sunrise to sunset), in order to appraise the environmental variations for a minimum and a maximum availability of external natural light, for different weather conditions and periods of the year.

These aims were at the basis of the study carried out for the daylighting design of the new Faculty of Maths, Natural Science and Physics library in Alessandria, which is presently at a design stage. The daylighting system conceived forthe library is a large south-oriented glazed surface equipped with a mobile micro-perforated aluminium louvershade. Quantitative and qualitative analysis were carried out for different louver tilt angles, in order to verify both the effectiveness of the screening effect and the internal availability of daylight during different periods of the year.

A similar procedure was used to assess the aluminium louvered shading system designed for the sky-light for of the new SACMI headquarter in Bologna. In this case, the screen was supposed to be fixed, so different louver tilt angles were tested so as to determine a suitable position representing a fair compromise forthe entire year between screening of direct sun-light and letting diffuse skylight in.

1. Conclusions

The paperdescribes the potential applications ofthe use ofscaled models and artificial scanning sky in the fields of daylighting design and research.

In particulartwo different categories ofapplications are highlighted: the comparison of environmental performances ofdifferent daylighting systems and the optimisation, during the design stage, of a specific daylighting system.

For the first category an exhaustive example, concerning the comparison of lighting environmental performances ofdifferent traditional shading devices, is presented. The systems, designed to ensure an equal energy performance (similar SF for both summer and winter period) were applied to the model of a sample classroom and tested under the artificial sky and sun. Results obtained through the simulations ofdifferent sky conditions and Sun paths showthe differences in the lighting performances, emphasising in particular best results for the horizontal fins and the external light shelf (considering daylight quantity, daylight penetration and uniformity over the cross section as evaluation criteria).

The quantitative and qualitative effect of different shading finishing was also assessed. Specularand semispecularfinishing used for internal light-shelves always produced higher illuminances and contributed to increase daylight penetration towards the rear part ofthe room. Nevertheless such finishing, and in particularthe specularone, created, when reached by direct sun light, high luminance areas on the ceiling, which can be a potential cause of discomfort glare.

For the optimisation of daylighting systems during the design stage, the use of a scanning sky simulatorallowed evaluation ofdesigned systems and comparison ofdifferent solutions: for instance the most effective tilt angle forfixed louvers of a shading device designed fora building skylight could be determined.

In conclusion, from the experiences carried out at the Daylighting Laboratory in Turin it comes out that the use ofscale models under artificial sky and sun is a useful tool for both daylighting design and daylighting research as it allows an accurate simulation ofdifferent daylight conditions (both standard or experimental), a quantitative and qualitative evaluation oflighting environmental performances and definition ofdaylighting systems’ geometric and photometric characteristics.

Gianni Scudo: Department Building & Environment Science & Technology (BEST), Politecnico di Milano Via Durando 10, 20158 Milano, ITALY Tel.:+39 02 23995729 Email: aianni. scudo@Dolimi. it

Alessandro Rogora: Department Building & Environment Science & Technology (BEST), Politecnico di Milano Via Durando 10, 20158 Milano, ITALY Tel.:+39 02 23995728 Email: alessandro. rogora@polimi. it

Claudia Losa: Department Building & Environment Science & Technology (BEST), Politecnico di Milano Via Durando 10, 20158 Milano, ITALY Email: c. losa@inwind. it

Aim of the research was develop guidelines for the refurbishment of public school buildings in Catania climatic area.

Main objectives of guidelines are to help the planner during his/her work in order to reduce energy heating, cooling lighting compsution improving of the same time the comfort condition inside the classroom.

The research has been promoted by the Catania’s council with the objective to define a program of refurbishment of existing schools. The refurbishment should have considered both the building structure, the energy and the environmental performances of the schools. Aim of the research was to define specific guidelines for the refurbishment of the buildings and the surrounding areas to get the maximum energy and environmental effect at the lowest cost. The problem of comfort inside the buildings, with special attention to summer conditions, has been considered of the maximum importance and has been analysed together with the energy consumption due to heating, cooling and lighting.

The retrofit interventions proposed are based on four elements (indicators of quality):

— current building standards and regulations;

— energy efficiency;

— thermal and lighting comfort (winter and summer conditions);

— building safety.

The research is structured in three phases:

— survey of the schools and use of a computer model to simulate the thermal conditions;

— analysis of energy simulations obtained from the computer model;

— definition of the strategies of interventions.

Evaporation flow rates

When plants are exposed to light they are able to take up carbon dioxide from the ambient air and produce carbohydrates under the use of light energy. The carbon dioxide uptake is accompanied by the loss of water, which is taken up by the root system. Water evaporation leads to a cooling of the leaf surface and produces a microclimate around the plants. The goal of the numerical model developed in the project is to determinate how this microclimate affects the energy balance of the builiding facade. To do so, the water flow rates evaporated by different species under different circumstances have been measured in order to use this

Figure 5: Evaporation flow rate. At the left, the same species grown in different conditions have different reactions to the same conditions. At the right, reaction of different species to the same conditions.

data for the numerical model. Illustrative results of the experiments are presented in Fig. 5.

The evaporation flow rates depend not only on the plant specie and on the ambient con­ditions, but also on the ambient where the plant has grown. Thus, it will be convenient to repeat some of these measures in actual facades.

Optical properties of the leaves

The optical properties of the plant leaves (transmissity and reflectivity) have been mea­sured in order to obtain data for the numerical model. Illustrative measures of Parthenocis­sus quenquifolia are presented in Fig. 6.

Solar-Institut Julich / Fachhochschule Aachen Heinrich-MuRmann-StraRe 5, 52428 Julich Tel.: 02461 / 99 -3532, Fax: 02461 / 99 -3570 www. sij. fh-aachen. de, info@sij. fh-aachen. de

K. Schwarzer, M. Werner, T. Hartz, L. Aliaga 1 Motivation

Experience with 20 different commercial simulation programs has been gathered at the Solar Institute in Julich. On the one hand, simulation programs with operator-friendly user interfaces for the design of standard systems are currently available. The advantages here are the short training period required and low price, but with the disadvantage of limited flexibility. On the other hand, there are programs available which offer flexibility in nearly all technical equipment concepts. The disadvantages here are the complicated operating in­structions which often lack clarity, and the long training period required.

Given this background, in 1996 the Solar Institute in Julich decided to develop computer models for solar thermal and conventional heating systems, using MATLAB-Simulink® /1/. At about the same time, and in the same Institute, the basics of a building model, which is the foundation of the toolbox "Lacasa” presented here, were established within the frame­work of both a dissertation and the project Solar-Campus Julich /2/.