Category Archives: BACKGROUND

The Purpose and Function of Lacasa

It was the aim of the project to develop a practical planning and diagnostic tool focusing on the analysis and optimization of energy use, in the framework of renovation and retrofitting programs, in existing buildings, as well as new buildings starting from the design phase. In order to ensure the practicality of the tool, the engineering firm GERTEC GmbH, Essen, was integrated into the project as an commercial partner of the Solar Institute Julich. The following functions were encompassed:

Function Group

Program Function

Model

Thermal simulations of buildings Models of the ambient building ventilation Library of building cross sections

Heating, ventilation and air conditioning equipment (HVAC) Integration of solar units into heating and air conditioning equipment

Data Format

Materials databank according to DIN 4108 Building elements databank from the manufacturer

Use of various weather datasets (test reference year, meteorological conditions)

Interfaces

Interfaces from CAD to VDI 6021 (reading in building data into the models) Interface to include components of other programs (for example TRNSYS) Interface to read measurement data Graphic and text representation of the calculations

Process

Parallel simulation of buildings and active HVAC-facilities

Determination of the parameters needed to analyse the energy characteristics of

existing buildings

Design of the control and regulatory systems of the technical installations

Supporting docu­ments

Heat output according to DIN 4701

Calculation of the cooling load according to VDI 2078

Integrated proof of thermal insulation

Analysis of a Combined System of a. Earth-Heat-Exchanger and a Heat Pump

Jorn Herz, Andreas Doll, Klaus Brinkmann
Umwelt-Campus Birkenfeld, Germany

Address for Contact:

Prof. Dr. Klaus Brinkmann
Umwelt-Campus Birkenfeld
Automation and Energy System Technology
P. O. Box 1380, D-55761 Birkenfeld/ Germany
E-Mail: k. brinkmann@umwelt-campus. de

This paper presents an analysis of the system technology of an earth-heat — exchanger combined to a heat pump, which was (ca. 1995 — 2002) realised at the building of the Umwelt-Campus in Birkenfeld, which belongs to the University of Applied Sciences Trier in Germany. The heat pump works for a recovery of the stored heat in a massive absorber at the air-outlet, in order to minimise energy losses in the atmosphere. Examinations and comparisons to others up to now realised earth-heat-exchanger projects in Germany, done by Jorn Herz for reaching his diploma degree, show, that the special configuration at the Umwelt-Campus Birkenfeld seems to be the first of that kind. This presentation gives an overview of the system technology and working principle. Measurements and mathematical modelling were done, in order to evaluate the efficiency of this combined system and to identify to advantages and disadvantages of this realisation. Additional, practical experiences with stability and working conditions etc., made by Andreas Doll, the responsible technical engineer for the Campus Buildings, are integrated.

MAIN TRENDS OF SUPERINSULATION RESEARCH

Only a few works have been devoted to the matters of electro-adsorption interaction of SVHI screens with the residual gas [1-5]. At the same time, the F. F. Vol’kenshtein’s monograph [48] is devoted to electronic process on semiconductor surfaces where the results of the 40-year work of the author and his colleagues in the field of physics and chemistry of semiconductor surfaces are summarised. The semiconductor surface in the work cited above is considered from the positions of the interface between two phases. The interaction between gas molecules of the residual medium and free semiconductor electrons and holes occurs at this interface. As the majority of metals have an oxide film, then their surfaces in most cases are semiconductor surfaces. Among works devoted to the physics and chemistry of semiconductor surfaces, the most substantial are monographs by K. Haufe [49] and S. Morrison [50], F. F. Vol’kenshtein [48], A. V. Rzhanov [51]. It is necessary to note a great contribution of the V. S. Kohan’s school into the theory of interaction of active gases with metal films [52]. A very meaningful is the monograph of the Indian physicist K. L. Chopra [38]
devoted to the investigation of physical processes passing in thin films of metals, semiconductors and dielectrics.

By the present time, the main tendencies of further development of the superinsulation have been carried out in the following directions. First of all, studies devoted to the optimal installation of the superinsulation [53], the process of vacuuming of the cryogenic equipment superinsulation [54-57], investigations of gas permeability of the superinsulation [58, 59], the determination of diffusion coefficients of residual gases in the superinsulation [60], investigations of the kinetics of gas release of heat-insulating materials in vacuum [61], investigations on studying of the distribution law of residual gases in superinsulation layers [62], investigations on studying if the unsteady pressure field in the superinsulation [63], investigations of the properties of superinsulation materials [64, 65], investigations of heat and mass exchange in the superinsulation [66-68]. The work [69] has a high theoretical and practical value, Mikhalchenko with colleagues have detected therein a hundred-fold pressure ratio in the middle of the sample over its thickness and on the outer insulation layer with the temperature of 77K. In the work [70], it has been obtained that the pressure in the superinsulation grows proportionally to the squared insulation thickness. In addition, it has been detected that the pressure distribution over the insulation thickness in the steady mode has a parabolic nature.

In order to improve the conditions of superinsulation vacuuming, it has been proposed to perforate screens [71]. Barron [72] has come to a conclusion that if the perforated hole area equals to 10% of the screen area, then the rate of gas pumping-out from the insulation increases approximately by 1000 times. In the work [73], it has been shown that gas releases of screens can be absorbed inside the insulation, for example, by means of the use of glass — fibre paper with filaments from activated charcoal as a pad’s material. In the work [74], it has been determined that gas releases of screens can be absorbed inside the insulation, for example, by means of a low-temperature gas absorber.

Studies are known devoted to surface effects on a dimension-quantised screen — vacuum heat-insulation in the conditions of cryogenic temperatures and vacuum [75], influence of surface centres on the gas medium formation in HIC, selection of a metallised coating of the superinsulation, optimisation of the technology of manufacture of a metallised film with the account of electro-adsorption phenomena on the film surface: selection of the crystal size to be applied onto the polymer film substrate, values of the thickness of the metal spraying onto the film, management of the metallised film properties by the introduction of special alloying gases at the manufacture, etc.

Quite a few works have been devoted to operational methods and means of maintaining and monitoring of the optimal mode of the superinsulation functioning [76, 77].

The investigations devoted to surface effects on dimension-quantised films in the superinsulation, influence of the surface centres of superinsulation screens on the gas medium formation in HIC, selection of the metallised coating of superinsulation screens, optimisation of the technology of manufacture of a metallised film with the account of electro­adsorption phenomena on the film surface, selection of the crystal size to be applied onto the polymer film substrate, values of the thickness of the metal spraying onto the film, management of the metallised film properties by the introduction of special alloying gases at the manufacture, management of the value of the surface potential of superinsulation screens by means of connection of the superinsulation screen to an external potential, etc., are completely absent.

In addition, the matters of selection of the protective casing of the reservoir, introduction of an additional "dry" volume into the cryogenic reservoir design between the
casing and the additional moisture-insulating shell are completely missed. The shell can be made with an overflow moisture-impermeable valve. As to the matter of exclusion of a moisture film on the outer heat insulation surface, we are aware of only one work [78].

It is well-known that the film alloying by gas impurities can lead to the improvement of their properties [79]. The task of management of the film properties by their alloying with impurities was stated in a number of works [80].

A special attention will be paid to the management of properties of screens on the polymer basis by means of their modification by the ion implantation. By the present time, a sufficiently large volume of work on the investigation of kinetic phenomena in conducting organic films has been carried out [81-86].

The complexity and diversity of processes being observed in heat-insulating cavities cause a necessity of the conduction of additional emergent experiments with the use of newest measuring apparatus.

The urgency of investigations on the development of a fundamentally new superinsulation is in the present time dictated by the beginning of intensive works on the development of ecologically clean transport on hydrogen in all developed countries.

Energy, Economy and Ecology Analysis

All levels of society should be sensitive to the environmental issues. The ecological parameters must be taken into consideration as a part of the external costs. But these costs someone has to pay. The sustainable development has to balance power supply and demand respecting both economical and ecological criteria. However, it will be very difficult to secure energy at low cost, with high rates of economy growth and acceptable pollution levels. Having this in mind, renewable energy resources could play a dominant role in the 21st century alone and in combination with other ecologically acceptable fuels.

The price of fossil fuels (coal, oil, natural gas) does not represent their true cost to the society. Besides many factors the ecological impost also has to be included in cost of fossil fuel. The impost consists of:

— Repayment of environment contaminators according to the emission of CO2, SO2, NOx,

— Repayments according to the burden of the environment-communal or dangerous waste,

— Repayments for the environment contamination caused by traffic — motor vehicles.

The example of solar energy utilization project described here shows savings of

thermal energy in the system of space heating and domestic hot water preparation. A yearly value of solar contribution at level of 70 % is expected. The solar contribution in electricity supply of the house is around 50%. Also a temporary excess of electricity produced in PV generator can be delivered to the network. The reduction of the emission of the CO2 at the rate of 6500 kg per year is expected.

The house is also equipped with rain-water collection system, saving almost 55% of overall sanitary domestic water demands.

2. Conclusions

The pilot project "Solar roof Spansko-Zagreb" shown here presents production of both thermal energy and electricity in the family house. In this work the possibility of energy savings in the system of space heating and domestic hot water preparation is presented in the case when solar energy is used, and electricity production from solar energy is shown. On the other side, almost ideal supplementation of the city gas as an additional fuel with solar energy, especially in the reduction of harmful gases emission is shown. The significance of this pilot project is in the usage of renewable energy resources, which are capable to ensure large enough amounts of energy for both economic growth and sustainable development for the well of future generation.

Simulation of buildings insulated according to passive house criteria and reference user behaviour

It is possible to reach high accordance of the measured and simulated room air temperatures, when very detailed input data is available. Little differences i. e. in the user behaviour can alter the results significantly because the heat demand of the building is very small (ref. Table 1). An increase of the room set temperature from 20°C to 25°C increases, for example, the space heating energy demand by over 50% (with all other parameters fixed).

For detailed simulations and comparisons the user behaviour taken from standards is not sufficient. Even user profiles evaluated from questionnaires are sometimes not accurate enough (this is especially true for the ventilation by windows). Figure 2 shows the examples for the daily distribution of persons in the apartment and the electricity demand other than HVAC system chosen in this study.

Figure 2 Average daily distribution of persons in the apartment (left) and electricity
demand other than HVAC-system (right) (Streicher et al. 2004).

THE INFLUENCE OF PHOTOVOLTAIC MODULES’. USAGE ON THE INNER SPACE ENVIRONMENT AND ITS. ARCHITECTURAL CONSEQUENCES

Janusz Marchwinski msc., Katarzyna Zielonko-Jung dr,
prof, dr Zygmunt Szparkowski

Faculty of Architecture, Warsaw University of Technology,

Koszykowa 55, r. 218A, Warsaw, 00-659, Poland
Phone Nr +4822 660 55 24, Fax Nr +4822 628 32 36, e-mail:j. marchwinski@wp. pl

GENERAL INTRODUCTION

The analysis of the influence of photovoltaic (PV) modules’ usage is focused on thermal and lighting environment in the inner space of the building and visual contact with its surroundings. This problem is connected with thermal and visual comfort of the user.

Since the main role of PV modules relies on electricity generation in the building, the influence of their usage on the inner space environment seems to be less important. However, as the PV module becomes an integral architectural part of the building, this aspect must be taken into consideration.

All the solutions, which are commonly referred to as “building integrated photovoltaics” (BIPV), may affect the inner space environment in a different way. In consequence one can observe, that the architecture of the building is being affected.

The main scope of the paper is to evaluate the influence of PV modules’ usage on the inner space environment in terms of thermal and visual comfort of the user. The paper is also focused on indicating the architectural consequences that may happen as the result of this influence. We aim at showing certain pros and cons connected with PV modules’ usage as architectural components integrated within the elevation and the roof of the building.

To prove our point, four non-residential buildings with various PV modules implementation have been chosen as a groundwork for our analysis. These are: library building in Mataro (Spain), laboratory building in Petten (the Netherlands), office building ”Doxford Int.” in Sunderland (U. K.) and Mont-Cenis Academy building in Herne-Sodingen (Germany).

Heat Supply systems

Compared to a conventional house, a high performance house has a very small heating demand (ca. 15 kWh/m2a), a micro peak heating capacity (typically under 10 W/m2) and shortened heating period (i. e. November — March in the moderate EU climatic area). The limit temperature for heating demand achieves 12 °C. This defines a new set of requirements for domestic technical systems. The heat production plant can be small and inexpensive, as also the heat distribution system. The very slow rate of heat loss means that the timing of the heat supply can be very relaxed. However, the auxiliary heat supply must shut down very quickly, e. g. when the sun shines, to avoid overheating and comfort problems.

To produce the needed remaining heat, 31 % of the projects rely on a small heat pump,

10 % burn biomass — primarily wood pellets and 14 % are connected to district heating.

size of the solar area to the net heated floor area [m2/m*]

0.6 —————————

■ solar DHW systems □ solar combi systems

■ solar air systems ■ solar electricity

average solar DHW : 0.05 m2 solar collector area per

Figure 4 Use of solar energy systems in the analyzed projects — size of the systems in relation to the gross area of the solar system to the net heated floor area of the building

The remaining 37 % of the houses have a fossil heating system (fossil fuel fired). Some projects have a combined heat and power system, increasing the overall efficiency. Most of the heat supply systems are combined with a solar thermal system to produce domestic hot water. In total, 67 % of all buildings use active solar supply for hot water production and 22 % for combined space and domestic water heating. 35 % of all buildings have a photovoltaic system to produce electricity. Figure 4 illustrates the ratio of solar thermal collector gross area to the net heated floor area of the building. This ratio averages 0.05 m2 collector area per m2 net heated floor area. For the PV-Systems the mean value is about 0.13 m2 module area per m2 net heated floor area.

Ventilation loss must be decreased while assuring best indoor air quality. In 68 % of the investigated buildings a mechanical ventilation system with heat recovery is installed. In some buildings (about 28 %) the mechanical ventilation is combined with an earth-to-air

heat exchanger (eta-hx). An eta-hx in high performance housing is a part of the strategy to increase the degree of ambient or renewable energy use. Its benefits in order of importance are:

• prevent freezing in the air-to-air heat exchangers of heat recovery systems,

• increase the temperature of the supply air,

• improve indoor comfort in summer by cooling the supply air.

The relative importance of these three functions varies with the general building concept and the climate. In the demonstration buildings with an eta-hx, the mean value for the specific surface area of the eta-hx per volume of air flow was 0.14 m2/m3h.

The benefit supplying air tempered by the eta-hx does, however, reduce the efficiency of the heat recovery from the heat exchanger. In some passive-houses the supply air is further heated, up to 50 °С, eliminating the need for radiators in all but perhaps the bath room. The mechanical ventilation rate in the buildings is usually designed to supply between 0.4 and 0.5 room volumes per hour.

Another method to reduce ventilation heating demand is by using an exhaust ventilation system. Fresh air can be preheated by solar air collectors ( in 11 % of the projects) or by using a sunspace (13% of the projects).

heat losses transmission

гдо, т2К ♦detached A semi detached ■ row • apartment

heat losses ventilation [W/m2k]

Figure 5 Transmission and ventilation losses of the analyzed buildings (related to facade area)

With this new ventilation strategies the specific ventilation losses can be reduced in the average to 0.30 W/rnF K, which is lower than the transmission losses. Figure 5 shows the relation between transmission and ventilation losses for the projects.

Most of the apartment and row buildings have transmission losses less than 0.4 W/rnF K (facade area) and ventilation losses lower than 0.6 W/rnFK (net heated floor area). These buildings are very efficient (passive-houses) and have heat recovery systems with earth-to air heat exchangers. The higher transmission and ventilation losses of the semi-detached buildings with less efficient building designs and exhaust air systems are also evident if the graph.

Indoor Surfaces Reflectance

In order to analyse the impact of the surfaces reflectance, daylight factors were monitored from 10.00 to 17.00 under overcast sky in two different cases. The relative difference between daylight factors observed in the test module and in a first scale model (cf. Figure 1.a), showing larger differences of surfaces reflectance (cf. Table 1, Scale model 1), were used to assess this impact. A subsequent improvement of the scale model by the way of a closer match of the surfaces reflectance (cf. Table 1, Scale model 2) was used in an attempt to reduce the divergence between the two kinds of daylight factors. To avoid any bias due to the sky luminance distribution, all models were placed next to the test module (cf. Figure 1.b); measurements in the model and the test room were carried out simultaneously.

Scale Model Location

The scale model location was considered as one possible main source of error, through the impact of different sky view factors and external reflected components : it was carefully analyzed by placing scale models close to the test module, but at different distance from the later (cf. Figure1.b). Work plane illuminances were monitored from 14.00 to 16.00 under clear sky, enhancing the contribution of the external reflected component, their relative divergence being compared. The scale model was placed first in another module, located only a few meters away from the test module, the corresponding window plane
being fully coplanar; the model was moved next to the test module in order to make it benefit from identical sky view factor and external reflected component. Scale model 2 was used in this case, to avoid any bias due to the surface reflectance; measurements in the model and the test room were carried out simultaneously.

Samples description

A set of glasses with geometrical obstruction, not commercial at the moment, was characterized to evaluate the luminous performance and the influence on the visual comfort for users. Obstructions and decor have different geometries and colours and reduce both the light transmittance and the view through the glazing.

The demand of decorated glass increases and the market provides multiple choices as concerns both, the production technologies (silk screen printing, acid etching, etc.) and the type of decorations (geometrical patterns, colours, shapes and drawings, etc.).

The glazing components characterized in this work are laminated glass panes (safety products) 30 x 30 cm2 in size. The decors seen in figure 1 are sublimated on a plastic interlayer and laminated between two glass panes (3 mm float glass).

This innovative system preserves the decor from aging and scratching and allows to use this decorated glass in applications usually avoided in the case of single glass panes. This particular safety glass can be used to decorate the facades of buildings, partition elements in public rooms, or shop windows and doors; it can be also utilized in interior design such as shower boxes, stairs, parapets, shelves, and so on.

The decor design has really no limits, since the technology adopted allows to print on glass every type of pattern and picture (i. e. points, lines, rainbows, water effect, rock effect, photographs, etc.).

Figure 1. Details of samples 6, 12 and 13

Normal Hemispherical Transmittance

Figure 2. Normal hemispherical transmittance of the selected samples

The three samples analyzed in this work features only geometric patterns (with different shapes, colors and dimensions) due to the difficulty to determine the visual properties of the artistic decors. Sample number 12, figure 1 on the left, has rectangular black obstruction on clear glass. The dimensions of the rectangles vary with the same pitch on the x and y axis. Sample number 13, on the right, has rectangular white obstructions on clear glass, but the texture varies along the two axis. Sample number 6, across the other samples in the picture, is the only sample with color. Its decor looks like a random distribution of blue rain drops on the clear glass.

Development of a High Energy Density Sorption Storage System

Gunter Gartler, Dagmar Jahnig, Gottfried Purkarthofer, Waldemar Wagner
AEE-INTEC, A-8200 Gleisdorf, Feldgasse 19, Austria
Phone: +43/3112/5886/64, Fax: +43/3112/5886/18, Email: g. gartler@aee. at

Long-term heat storage enables a major technical break-through for an effective year round use of solar thermal energy. Thermo-chemical processes as used in sorption storage systems give a new chance to store the heat with a high energy density and for extended periods. The project MODESTORE (Modular High Energy Density Sorption Heat Storage) is being supported by the European Commission since April 2003. The major objectives of this project are the monitoring of a first generation system installed in the past and the development of a second generation prototype. The main improvement is the integration of key components (evaporator/condenser and the reactor) into one single container. A modular design enables to operate in a wide variety of applications in the near future. Test runs of the installed first generation system have been done under controlled conditions to gain operation experience and to assure a detailed characterisation of the complete system. A control program was written in order to operate the storage in a reliable and automatic way. Detailed experimental data of all tests were obtained, analysed and evaluated. Furthermore a simulation model was developed. The validation of the simulation model was done comparing simulated and measured charging and discharging cycles. The model represents well the basic performance of the adsorption heat store. The newly developed second generation prototype will be engineered and extensively tested, analysed and evaluated under practical conditions to allow the finalisation of the product development and identification of the most attractive market.