The results of ParaSol and Rayfront simulations will be described in this section. Figure 1 shows the annual heating demand as an average value for all four directions for each glazing type and climate. For the Stockholm climate the energy demand decreases from 78.2 kWh/m2,yr to 68.4 kWh/m2,yr for the low-e DG and 67.6 kWh/m2,yr for the AR low-e DG window. The low-e AR DG decrease the energy demand with 2.1% compared to the low-e DG. For all climates, replacing one of the panes in a double-glazed window from a clear to a low-e coated pane reduces the heating demand by 12-14%. Applying an AR-coated low-e pane reduces the heating demand somewhat further, approximately with 1-2%. The total energy saving for this room is about 160-240 kWh/year.

Summertime, the indoor temperature is not extremely high. The most common way to reduce overheating in multi-family houses in Nordic climates is to use cross ventilation by opening windows. The highest temperature without this extra ventilation is 340C for the standard glazing, however just for a couple of hours per year. For the

Applying an AR-coating on a low-e window increases the light transmittance by 13% and the transmissivity by 14%. The calculated solar and light transmittance and the transmissivity Tr for the three glazing combinations are displayed in Table 4.

low-e windows there are almost 1000h with temperatures over 30oC. Figure 2 describes this as a duration diagram i. e. for Stockholm in the south direction. The Copenhagen and Helsinki climates (not shown here) have very similar results. Figure 3 shows Tsol (average values of all four directions for May) for each window and climate. The difference of the low-e and the AR low-e DG is about 3%. The g-values are shown in figure 4 (average monthly values for May in all four directions) for each window and climate. The difference between g — values of the low-e DG and AR low-e DG is approximately the same as for the

A building during its existence affects the local and global environments via a series of interconnected human activities and natural processes. At the early stage, site development and construction influence indigenous ecological characteristics. Though temporary, the influx of construction equipment and personnel onto a building site and process of construction itself disrupt the local ecology. The procurement and manufacturing of materials impact on the global environment. Once built, building operation inflicts long-lasting impact on the environment. Once built, building operation inflicts long-lasting impact on the environment. For instance, the energy and water used by its inhabitants produce toxic gases and sewage; the process of extracting, refining, and transporting all the resources used in building operation and maintenance also have numerous effect on the environment.[4]. Therefore, the goal of a sustainable design is to find architectural solutions that guarantee the well being of the global ecosystem, constituted of inorganic elements, living organisms and humans.

Considering the sustainable design goals defined before, this project attempted to minimize the combined impact of architecture through the use of the following sustainable design strategies:

1) Low energy design and thermal comfort

2) Solar energy use through grid-connected PV system and solar water heating system

3) water conservation: rainwater coolection system and waste water treatment

4) materials conservation: recycled materials and low embodied energy materials.

Anna Werner, Arne Roos, The Angstrom Laboratory, Department of Engineering Science, Uppsala, Sweden

Introduction

Solar radiation reaches the windowpane from many angles simultaneously. Most of the radiation, however, is direct radiation, coming from the direction of the sun. The incidence angle of this radiation varies from one moment to the other. Radiation coming from different directions are affected differently by the windowpane. The absorptance for instance, is typically lower at an incidence angle close to 90° than at an incidence angle close to 0°. This angle dependence is useful in some applications (angular selective windows), but it might also pose a geometrical problem. To calculate the instantaneous overall absorptance (integrated over all incidence angles), one needs to know how much radiation comes from each angle at each moment [3]. In this study, we have focused on the maximum power absorbed in a windowpane from different angles. The reason for this limited analysis, is that we want an empirical model for the angular variation of the solar absorptance that gives as accurate estimations as possible for these extreme values that are crucial when evaluating thermal stress on a windowpane and surface temperatures [1].

If there were no (refraction in the) atmosphere, 1367 W/m2 would reach a pane perpendicular to the sun at our distance1. In the atmosphere, radiation is scattered and absorbed so that less power actually reaches the Earth. We have focused on Stockholm data. Approximately, 1000 kWh a year reaches a horizontal surface of one square meter in Sweden. If, instead, the surface is tilted 45° with respect to the horizontal, 1150 kWh will be captured, and if the pane follows the sun, 1450 KWh can be collected. These are experimental values. Climate files exist with the direct and diffuse irradiation on a horizontal surface for different locations and years. The calculations of the irradiation on a vertical surface were based on these data. We used data from 1982. Figure 1 shows the maximum solar power in our test year (W/m2) for each angle of incidence for a north facing window, an east facing window, a south facing window and a west facing window.

The solar constant, as used by the World Radiaion Center and in [3] with an error estimate of ±1%

Figure 1 Maximum directly irradiated power versus angle of incidence for four differently oriented windows in Stockholm in 1982.

Table 1 shows that a window facing the north never is hit by radiation from an incidence angle lower than about 40°. It also shows that for windows facing one of the other three major orientations, the highest (hourly) power is attained at incidence angles around 20°. Table 1 shows when each of these maximas occurs (month of the year, day of the month, hour of the day). In five cells no figures are shown, since according to our simulations a north facing window in Stockholm never receives direct sunradiation from an angle below 40°.

Some of the irradiated power will be absorbed by the window. It is possible with Fresnel calculations to find out exactly how much solar power is absorbed in each pane.

Different windows have different properties at different angles of incident. We studied 27 different windows, with 62 panes altogether. Not only the level of solar absorptance is different for each pane, but also the angular variation of this solar absorptance. It would be impossible to show all the angular properties of all panes here. Instead, we show only one example in Figure 2. It shows how much solar power is absorbed in the outer pane in a double pane window where the inner glass is a 4 mm clear float glass and the outer is a 4 mm grey float glass. By comparing figure 2 with figure 1, it is realized that radiation coming with one angle of incidence is not affected in the same way by the pane as radiation coming from another angle.

•North……………. East -8— South -*-West |

Figure 2 Maximum power absorbed versus angle of incidence for one of 62 studied panes; the outer pane in a double pane window where the outer pane is a grey 4 mm float glass and the inner pane is a clear 4 mm float glass, no coatings applied. The climatic data used for producing the diagram are the ones shown in Figure 1 and multi-Fresnel formalism was used to calculate the pane optical data.

The new commercial buildings programme includes the following support activities:

Energy advice and auditing service

Energy advice given at the moment when investment decisions are made is one of the most important tools for the promotion of energy efficiency and renewable energy sources. Therefore, the O. O. Energiesparverband offers a broad energy advice service programme for households, companies and public bodies. Energy advice is also part of the sustainable buildings programme implemented by O. O. Energiesparverband.

For companies and industry the service has been extended recently, offering 2 days energy advice for businesses, 75% of the costs are covered by the regional government.

In order to promote RES applications in companies, together with energy experts, energy strategies for four industry sectors (metal, wood, hotels, real estate) were developed.

Based on these guidelines, individual energy advice sessions for the companies were held, leading to concrete RES installations.

Information & awareness raising activities

A number of information and awareness raising activities are carried out including publications and events. Recently as part of the international conference World Sustainable Energy Days for example the conference "Tomorrow’s Buildings" was held which offered insights into forward-thinking innovations in energy and buildings technologies.

One main part of the information activities is the promotion of large scale solar thermal installations. In order to overcome the barrier of lack of know-how, a planning manual ("solar guide") was developed and training courses for the planning and installation of large solar thermal systems were organised.

U. D.J. Gieseler, F. D. Heidta

University of Siegen, Division of Building Physics and Solar Energy Walter-Flex-Str. 3, D-57068 Siegen, Germany http://nesa1.uni-siegen. de, e-mail: heidt@physik. uni-siegen. de

Abstract

For low-energy buildings, passive solar gains can contribute significantly to the heat bal­ance. For the calculation and optimisation of the energy performance of low-energy build­ings, the precise quantification of solar gains is therefore quite important. The total solar gains can be calculated from the available solar radiation and the geometry of the building. However, the relevant part of the solar gains, which is really usable to substitute heating energy, is more difficult to obtain. This part depends on the actual temperature inside the buildings, which, in turn, is influenced by the amount of solar and internal gains, heat ca­pacity, as well as the building services. In this paper, a method is presented, to calculate the utilization of solar gains with a thermal building simulation software on a monthly basis. The results show, that for small to medium sized "passive houses" in standard German weather conditions, the utilized solar gains for the whole year is roughly (10 ± 2) kWh/(m2 a), and does not depend significantly on the details of the building construction.

Introduction

Solar radiation influences the heat flux through the transparent and opaque envelope of a building. Whereas solar radiation on the opaque envelope can reduce the transmission losses, the energy flux through the glazing of windows is denoted as "passive solar gains". In low-energy buildings, passive solar gains contribute significantly to the total heat bal­ance, consisting of heating energy, solar gains, internal gains, transmission losses and ventilation losses. Due to their time dependent and irregular availability, only a fraction of solar gains is really usable. The other part of solar gains obviously increases the indoor temperature above the desired level, i. e. it produces overheating. Purpose of this study is the accurate determination of the amount of usable solar gains, which may depend on the type of construction of the building, i. e. window type and their distribution on different ori­entations, effective heat capacity and heat loss coefficient or demand of heat energy, re­spectively. Thermal simulation methods allow to calculate both, the solar gains and the temperature distribution inside the building, by taking into account all relevant influences. The utilization of solar gains and the overheating hours are therefore calculated with TRNSYS (Klein et al., 1976). After the description of the calibrated building models, the calculation method for solar gain utilization is introduced, which is based on these models. Finally the results are presented, which are focussed on the utilized part of the solar gains for these buildings or buildings types, respectively.

The high demands for level of lighting on the bookshelves and the architects wishes for the artificial lighting system, causes the heating load from artificial light to be much higher than the heating load from people and equipment. The overall internal heating load is high and will give high indoor temperatures outside the heating season. A effective way to overcome this problem is to control the artificial lighting system, especially that on the bookshelves in such a way that they are shut off or subdued most of the time outside heating season.

Daylight simulations showed that it is possible to shut off most the artificial light about 65% of the opening hours if controlled by the level of daylight at minimum 200 lux. In the BSim2002 model of Albertslund Library the artificial light at the bookshelves is subdued and shut off most of the time during summer as found in the daylight simulations.

4.3 Indoor Thermal Climate From the simulations made with BSim2002 the following indoor tempera" tures in different parts of the library has been found during opening hours. Figure 13 shows the mean indoor operative temperature during opening hours for the different sections of the library during a warm and sunny week.

Figure 13 shows that the indoor temperatures are at a satisfying level in the summer. Table 1 shows the annual number of hours the mean indoor operative temperature exceeds 26 °C and 27 °C, respectively for all sections in the library.

3.5. Conclusion

According to Danish guidelines indoor thermal climate in offices, DS474, the annual number of hours during the opening

hours for a whole year should not exceed 100 of hours above 26 °C and 25 hours above 27 °C and the maximal indoor temperature should not exceed 30 °C. Table 1 and figure 13, shows that these guidelines are held for Albertslund Library. Furthermore, table 1 shows that the amount of hours with overtemperatures are low. The east section of the library has a high internal heating load per m2 and only one skylight for exit, thus getting higher indoor temperatures then the rest of the library. Overall it can be concluded that the indoor thermal climatic conditions for Albertslund Library is satisfying.

2. Conclusions

Based on the detailed simulation work that has been carried out during the design phase the following overall conclusion can be made.

Akos Nemcsics, College of Engineering Budapest, Tavaszmezo str. 17, H-1084 Budapest, e-mail: nemcsics. akos@kvk. bmf. hu

In this work presents two earth houses which are planned in a natural hill. The houses are supplied with equipments for solar energy. The house is entirely sunk in to the earth where only one facade is free from the earth.

Energy Balance of Earth House

The property of energy storage and heat balance of earth is a well known and often used concept in the ecological and solar architecture [1]. The humid earth has a large specific heat, so this medium as building material has a very large thermal inertness. Though this medium has approximately constant temperature, the feeling which it causes is different, depending on the enviromental temperature. We have the feeling that the earth radiates warm and cold in winter and in summer, respectively. This work presents two earth houses which are planned by the author in a natural hill in Hungary. Both houses are provided with equipment for solar energy utilization such as solar cells and solar collectors [2]. The houses are entirely suk in the earth where only one or two facades are free from the eath. The natural illumination of this house is solved from the facade side and from above with the help of flues. One of this houses is in highlands and another is in structured lowland. Both houses are under construction.

Earth House in Highlands

This house is being built in a mountainous district of Hungary, called the Pilis. The house is entirely sunk in the earth where only one facade is free from the earth. The house has one level, which contains three rooms, a kitchen with dining room and a living room, two baths and a study [3]. The living room, the dining room and the study receive the light from the windows on the facade. The serving rooms receive their light from the lighting flues. The house provided with natural ventillation. The walls and ceiling are from monolite steel concrete shell. The isolation against moisture is made from special recycling plastic foil [4] which perfectly operated in some similar estabilishments. We have to reckon on radon diffusion. The above mentioned foil serves for the isolation against the radon gas leak, too. Great part of the energy need is met by sunshine with active and passive utilization. The frame over the terrace is covered by solar cells [5]. The height of the retaining wall on the facade changes. The arched edge of the retaining wall follows the silhouette of the surrounding hills. According to the author the ecological building suits the enviromental not only energetically but also easthetically. The waste management is solved with root zone method. The ground-plane and the facade are shown on the figures 1 and 2, respectively.

After optimising the products with the wall sample tests we equipped several office rooms with PCM plaster. But when measuring real office rooms with PCM, the different user be­haviour made comparisons very difficult. To avoid these problems and to quantify the PCM — effect without user-influence, the Fraunhofer ISE built up two new real size testrooms at the facade-testing-facility with a light weight construction and equipped them with a PCM and a reference plaster. Both rooms were provided with detailed measurement equipment and identically controlled. Figure 6 shows the exactly to the south arranged testrooms from outside. The two testrooms on top of each other at the left side were used for the measure­ments. The testrooms were built up in a typical light weight construction consisting of gyp­sum plasterboard mounted on wooden slats with insulation. This setup is mounted on the 14 cm thick PU-wall of the cabin. Both testrooms can be controlled ventilated and were equipped with outside shading. During the measurements both testrooms were run with the same conditions.

Within the project we tested two different PCM-products for a one year period each. In 2002 we tested a dispersion based plaster with 40% weight PCM and 6 mm thickness and in 2003 a gypsum plaster with 20% weight PCM and 15 mm thickness. In Figure 7, the measured wall — and air-temperatures of three days with night ventilation (ac/h=4) can be seen for the 6 mm PCM plaster. In the area of melting temperatures of the PCM (24-27°C) the temperatures of the PCM-testroom rise slower than the temperatures of the reference — testroom. After achieving 27°C the temperature in both testrooms rises parallel, so that a temperature difference of 4K in the maximum was achieved. Additionally, the temperature — maximum was reached one hour later in the PCM-room. During night the temperatures in the PCM-testroom are higher than in the reference testroom. But still the storage is over­loaded without shading at the big south window (Fig. 7, last day). Therefore we have in­stalled an outside shading, which is going to be activated automatically on hot days. Fig­ure 8 shows the resulting temperatures curves. The temperature in the PCM-testroom lies at the maximum about 2K under the reference temperature. The accumulated amount of hours at a certain temperature during three weeks with shading are shown in figure 9.

In the reference room the temperature lies more than 50 hours beyond 28°C whereas the PCM testroom is only in about 5 hours warmer than 28°C.

SHAPE * MERGEFORMAT

time

Figure 8: Wall-temperatures with night ventilation and shading

remperature [° C]

Figure 9: cummulative frequency function of room temperature

Reference Wall—————- PCM Wall ————-

Figure 10: measured temperature profile during experiment with the gypsum PCM-plaster

Fig. 10 and fig. 11 shows the same measurements for the 15 mm gypsum plaster in 2003. Again it was possible to lower the temperatures in the PCM equipped room for up to 4 K and the reduce the hours above 28°C significantly.

One of the main limitations of that system is the heat sink at night. On order to function properly, the passive systems need a higher airchange at night. Since this might still limit the systems, active cooled systems (e. g. with a cooling tower and capillary tubes in the plaster) are under development.

Results and discussion

Microencapsulation gives us the possibility to implement PCM into conventional building materials. The microencapsulation has the advantages of easy application, good heat transfer and no need for protection against destruction. The measures data shows the potential for PCM products to reduce the cooling demand and increase the comfort in lightweight buildings. It is important that PCM areas are dimensioned according to the ex­pected loads and existing shading devices. It is also necessary to ensure that the storage can be discharged during night with an adequate ventilation. The ventilation can be real­ized by mechanical ventilation or through constructional designs for example with associ­ated atrium. Products are on the market and first office buildings have been realised. Active, water cooled systems are under development, which may overcome the limits of night cooling for the passive systems.

Acknowledgements

The authors are grateful to German ministry of science and work (grant no. 0329840 a-d) for funding this work and to their industrial partners BASF, caparol, maxit and sto.

Literatur

[1] Neeper DA. Thermal dynamics of wallboard with latent heat storage. Solar Energy 2000;68:393 403.

[2] Khudhair A, Farid M, Ozkan N, Chen J. Thermal performance and me­chanical testing of gypsum wallboards with latent heat storage. In: Pro­ceedings of Annex 17, advanced thermal energy storage through phase change materials and chemical reactions feasibility studies and demon­stration projects (www. fskab. com/annex17), Indore, India, 2003.

[3] Farid MM, Kong WJ. Under floor heating with latent heat storage. Proc Instn Mech Engrs 2001;215:601 9.

[4] PSchossig, H.-M. Henning, T. Haussmann, A. Raicu Phase change ma­terials in constructions;Phase Change Material Slurry Scientific Confer­ence and Business Forum 23-26.April 2003 Yverdon-les-bains Switzer — land, Proceedings Page 33-43

The Italian rules, such as, for example, the Commission International de I’Eclairage (CIE) recommendations, provide reference values for the parameters being able to defining the overall quality of a lighted room, e. g. the illuminance level, the daylight mean factor and the illuminance ratio.

The illuminance level should be sufficient to distinguish the details of what is wished to be observed as regards the visual task to be performed and to the required precision. The illuminance level recommended by the rules has been evolving, in the course of time, to more and more high values. Think, for instance, that the illuminance level currently considered optimal for workplaces varies from five to ten times more than the one fixed 50 years ago (e. g. General rules on the hygiene of work, Italy — 1956).

The rule UNI 10380 [8] provides, for various type of rooms, the recommended values of the mean horizontal illuminance on the work plane (taken as reference values in this paper). For libraries the maintained mean illuminance value Em equals 500 lux in the reading areas (in which the visual task coincides with the reading, study and consultation of documentary material), while it equals 200 lux in the areas provided with shelves (in which the visual task coincides with the reading of the back of the books contained in the shelves). However, the advised values should be considered to refer to artificial light and not to the natural one (with which this project is concerned). Moreover, it should be remembered that a given illuminance is considered to be comfortable not only according to the recommended values, but also depending on other factors, e. g. the colour rendition and the direction of the emitted light.

As regards daylighting, both in the Italian and foreign rules recommendations can be found, which are, in this case, provided in terms of daylight mean factor; the rule UNI 10840 [9] advises a value equalling the 3% (such value is taken as reference in this paper).

Finally, among the parameters most often used to verify the natural or artificial lighting quality inside a room there is the illuminance ratio, defined as the ratio between the minimum and mean horizontal illuminance values at the work plane. For this ratio the rule UNI 10380 [8] provide for a minimum value equalling 0.8 (such value is taken as reference in this paper).

Building (SIEEB)

R. S. Adhikari, N. Aste* U. Beneventano, F. Butera, P. Caputo, S. Ferrari and P. Oliaro
Dept. Building & Environment Science & Technology (BEST)

Politecnico di Milano, Via Bonardi 3, 20133 Milan, ITALY

Dipartimento di Energetica, Politecnico di Milano
Piazza Leonardo da Vinci 32, 20133 Milan, ITALY

1. Introduction

The energy structure of China is coal-based, with coal consumption amounting to 60% of total energy consumption (Chang et al.,2003), thus resulting in emission of large quantities of pollutants and greenhouse gases (GHGs). Building industry is one of the key energy­consuming industries in China, and it is strategically important to introduce advanced environmental and energy technologies into this field and to promote the construction of green energy-saving building.

China is experiencing an extraordinary expansion of its building stock. From year 1991 to 2000 residential buildings were built for nearly 5 billion square meters. In only four years (1996-1999) energy consumption of the building sector jumped from 24.59% to 27.81% of the total energy consumption. It is expected that the building stock, residential and commercial, will double by year 2015 (Chen, 2004).

The Sino-Italy Environment & Energy Building (SIEEB) is an intelligent, ecological and energy-efficient building: a model for a new generation of sustainable buildings. It is a 20.000 m2 building, 40 m high, located in the campus of Tsinghua University in Beijing, and it will host a Sino-Italy education, training and research centre for environment protection and energy conservation. The SIEEB, mainly financed by Italian Ministry for the Environment and Territory, in the framework of the Sino Italian Cooperation Program for Environmental Protection and co-financed by Tsinghua University, is also regarded as a platform to develop the bilateral long-term cooperation in the environment and energy fields, and a model case for showing the CO2 emission reduction potential in the building sector in China.

The building design is being carried out by the Department of Building and Environment Science and Technology (BEST) of the Politecnico di Milano, in cooperation with Tsinghua University, MCA Mario Cucinella Architects and China Architecture Design & Research Group, in a collaborative experience among consultants, researchers and architects. This integrated design process is a most distinctive part of the project and a key issue for green buildings.

In the preliminary design process, a number of appropriate shapes were considered and a feasibility analysis was carried out to check how the building was able to cope with all the requirements in terms of available area, specific building volume and space distribution. The resulting shapes were then analyzed in terms of their solar performance. Using the shape analysis, best shape was developed with the aim of maximizing solar gains in winter and minimizing them in summer. Further, the designing of SIEEB building is carried out on
the basis of various advanced technological solutions and control strategies which include sun shading, radiant heating and cooling, displacement ventilation, efficient artificial and natural lighting etc.

This paper presents the results on the energy performance of the SIEEB building design based on the best shape and advanced technological solutions and control strategies.