Category Archives: EuroSun2008-4

Lighting index Cm according to the orientations of openings

Figure 4 presents the results of the lighting index for different d/h ratio and for two different opening azimuths. d represents the length of the overhang and h the height of the window. These values of Cm are also compared to the PERENE requirements.

One can notice that the objectives of PERENE are too difficult to meet. We have assumed that the glazing has a transmittance equal to 1 (the window is opened if it is used in natural ventilation). PERENE requires values of Cm of 0,3 and 0,25 for windows facing North and West respectively.

Values of Cm of 0,3 and 0,5 are respectively demanded for openings oriented East and South. Only a d/h ratio of 1.5 could allow to meet PERENE for an East-oriented window.

To meet acceptable values of Cm, it would be necessary to reduce the transmittance of the glazing, what is not possible if this one is used in natural ventilation. It would be necessary to reconsider the requirements of the PERENE standard, at least for this type of solar shading

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Figure 4: Values of lighting index Cm for different d/h ratio and for North and West oriented windows. d represents the length of the overhang and h the height of the window

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Figure 5: Values of lighting index Cm for different d/h ratio and for East and South oriented windows. d represents the length of the overhang and h the height of the window

Simplified integration of PV in sealed glazing windows. — development and demonstration of a complete system

XP. Haugaard, 2D. Aara, 3P. Poulsen, 3B. Bentzen, P., 4P. M. Nielsen and 4J. Andersen

1 Esbensen Consulting Engineers A/S, Gammel Koge Landevej 22, 2500 Valby, Denmark
2 Gaia Solar A/S, Hammerholmen 9-13, 2650 Hvidovre, Denmark
3 FAKTOR 3 ApS, Vesterbrogade 24b 2. sal, 1620 Kobenhavn V, Denmark
4 Idealcombi A/S, Norre Alle 51, 7760 Hump, Denmark
* Corresponding Author, p. haugaard@esbensen. dk

Abstract

The project group is developing a low-cost PV-window for building owners and architects to use in building designs for both new and retrofit buildings. With a U-value of 1.20 W/m2K the developed PV-window fulfills the requirements within the Danish Building Regulation and as a bonus it produces electricity to the building.

Architects have found the PV-window interesting to use in building designs hence it offer many different possibilities to regulate the thermal indoor climate, daylight penetrations, reflections and communications. Tests have shown, depending on the design and layout of the PV-pane, that the PV-window can supply sufficient daylight to buildings.

The PV-window addresses the field of making energy right buildings using the energy falling on the buildings to supply itself in a fully integrated an aesthetical way and not as an add-on to buildings. It helps reducing the need for primary energy and gives the building a clearly environmentally green profile.

The development of this product has not been completed and will continue.

Keywords: PV-window, Building Regulation, low cost, custom design

1. Introduction

1.1 Scope

From the proactive strategy of reducing prices on integrated PV-systems the project aims to develop a PV-window which is cheaper than and technical fully compatible with the existing relative expensive standard PV-panels. Hence it is also the aim to develop an elegant PV-window solution that integrates architecture, aesthetics and flexibility in its design thus becoming an elegant attractive solution for both new and retrofit buildings. The PV-window must apply to the current Building Regulations in Denmark which has been tightened in 2006.

1.2 Objective

It is the objective to reduce the price on the PV-window by up till 20 % or more compared to similar products, fulfill the Danish Building Regulation, integrate, demonstrate and test the PV- window in an actual building and learn how it influences on thermal indoor climate in spaces.

The project is a part of the Danish PSO-F&U scheme sponsored by Energinet. dk.

Winter Counter Effective Human Intervention in Fenestration Shading Strategy

2.1. Results of Winter Shading Simulation Profiles

The results from computer building simulations, of various shading profiles caused by unexpected occupant intervention with the solar aperture, other than the one specified for the “Zero Energy House”, are analysed and assessed having as basis the optimum fenestration shading strategy for winter as defined below.

a) Optimised Fenestration Shading Strategy for Winter

The optimized fenestration strategy for winter from the previous research study “Shading” [1] is outlined as having all glazed area unshaded during the day time to obtain maximum solar gains and achieve comfort indoor conditions in the range of 18.6 — 20.6 degrees Centigrade (Table 1, 1.0).

b) North Window Shutters Shaded

If North window shutters (Area=3.5m2) are left closed during the day in winter, the indoor temperature reduces by 0.1 to 0.2 degrees Centigrade (Table 1, 1.1) i. e. 1% to 1.5% departure from the temperature achieved in the optimized fenestration profile (Table 1, 1.0). However the indoor temperature is maintained within the comfort range for winter (18.6-22.6 deg. Celsius).

c) North and West Window Shutters Shaded

When in addition to North window shutters, the West ones are left closed during winter days, an insignificant temperature of further reduction of 0.1 degrees Centigrade occurs, and that only at certain hours of the day no obvious pattern (Table 1, 1.2). The small extent of temperature reduction is attributed to:

i) Orientation — West orientated windows have no direct solar gains in winter.

ii) Window Area — The west window area amounts only to 0.50m2. The indoor temperature is maintained within comfort levels.

d) North, West and Half South window Shutters Shaded

When in addition to North and West window shutters half South window area remains shaded during the day, an indoor temperature reduction of 4.0 to 5.0 degrees Centigrade incurs i. e. 23% to 30%. This temperature drop lowers the indoor temperature below comfort level by 2.0 to 5.2 degrees Centigrade (Table1, 1.3). The largest drop, of 5.2 degrees Centigrade, occurs between

09.0 to 22.00 hours. This span of time is that receiving the most of direct solar gain followed by six hours in the evening, as the result of time lag. The rapid reduction of indoor temperature is expected due to:

i) Orientation. South facing windows invite amounts of solar gains incident at small angles in winter. Thus interception of solar radiation on this orientation has direct effect on indoor temperature.

ii) Window Area. The south glazing area with solar aperture is limited by 17.5m2 which is a considerable amount of glazing reduction and consequently solar gains.

e) All Windows Shaded

When all windows remain shaded during winter days, indoor temperature decreases in the rate of

9.0 to 10.5 degrees Celsius (Table 1, 1.4). The additional shaded window area is of equal (17.50m2) as in the previous shading window profile above (Table 1, 1.3) however the indoor temperature reduction in current profile is 1.0 degree more. This is expected as all glazed area is shaded and there is no solar access at all. The indoor temperature drops further by 4.0 degrees to its lowest levels which at certain hours (09.00 to 18.00) is even lower than outdoor temperature (Table 1, 1.4).

Performance Ratio results

The performance results show that amorphous silicon modules installed in the park have an average performance ratio of 0.76 and the multicrystalline modules installed in the facade have a value of 0.84, due mainly to lower average irradiance values leading also to lower average working temperatures.

Table 7. Yearly performance ratio averages in the PV Facade and PV Park systems.

Year

PR

PR

PV Fagade

PV Park

2006

0.844

0.745

2007

0.832

0.771

Performance: energy and comfort

The annual heating energy demand of the Passivhaus proposed for Portugal has been estimated as 16.9 kWh/m2, of which 11 kWh/m2 are supplied by the solar system (in this analysis priority of the solar system is given to heating and the solar fraction for domestic hot water is 48%). The annual cooling energy demand is 3.7 kWh/m2. The sum of net heating and cooling demand is

9.6 kWh/m2/yr. According to the thermal regulation, the limits of heating and cooling for this house built in Lisbon are 73.5 and 32 kWh/m2/yr, respectively. See fig. 2.

Подпись: 73.5 Standard House (DL 80/2006) Portugal Rassivhaus Fig. 2. Predicted annual heating (red) and cooling (blue) demand for a Standard House and Passivhaus 80 70 60 50 40 30 20 10 0

The analysis of the thermal comfort is based on the resultant (or operative) temperature, which is the average between air and radiant temperature. The comfort criteria adopted during the summer analysis were based on the calculation of comfort indexes. [6]

This prototype, with an active cooling, has a Fanger Comfort Index of 811 (the house is penalized by the influence of the high glazed area on the radiant temperature). If no active cooling is present, the Adaptive Comfort Index (AI2) applies and is 16. The resultant temperature is kept below 25°C for 71% of the occupied time, and below 28 °C during 98% of the occupied time. To reduce overheating the size of the windows and the thermal insulation should be reduced (though this increases the heating demand). See fig. 3 for the simulated distribution of the indoor and outdoor temperatures in a hot summer week with the Lisbon’s weather file. In winter, the low-power heating system of 10 W/m2 is in use, resulting in only 8% of time with a resultant temperature below 19.5°C (the lower temperature achieved is 18°C). Indoor temperatures show a reduce variation especially in comparison to the outdoor temperature fluctuation.

External Dry Bulb Temperature Indoor Resultant Temperature

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Fig. 3. Indoor and outdoor temperatures during a very hot week, without active cooling, in Lisbon.

4. Acknowledgements

The two Portuguese partners would like to acknowledge the remaining partners and subcontractors of the project and the EC financial support for the work developed within the project Passive-On (‘Marketable Passive Homes for Winter and Summer Comfort’ EIE/04/091/S07.38644, 2004-‘07).

5. Conclusion

Clearly, there is a trend to move towards low energy buildings with comfortable indoor conditions and the Passivhaus standard may be an economically feasible solution to achieve those aims. A discussion is raised whether there is the necessity to create airtight buildings with heat recovery mechanical ventilation. In relatively mild climates of Europe where many people still routinely sleep with their windows open, the adoption of a mechanical enforced ventilation system may be compromised. Strategies that combine natural ventilation, solar control and high thermal inertia have been accepted as possible solutions to implement in places with climate conditions similar to those studied within this project. A set of preferred passive/hybrid systems which allow the energy limit and the quality requirement to be met cost-effectively were also defined. An effective solar control and a night ventilation strategy, which dissipates solar and internal gains, can reduce the power of the active cooling system or make its installation unnecessary.

Previous analysis shows how the strategies adopted for the design of a Passivhaus for the heating and cooling climate of Lisbon can be successful, both regarding the energy demand limits and the comfort levels requirements. Although the specific design may be very different from the simple layout presented, the applied strategies have proven effective in reducing energy consumption.

References

[1] Directive 2002/91/CE of the European Parliament and of the Council of December 16 2002 on the energy performance of buildings, Official Journal L 001 of 04/01/2003 p 0065-0071;

[2] Action Plan for Energy Efficiency: Realising the Potential, INI/2007/2106: 31/01/2008 — EP: non-legislative resolution;

[3] Code for Sustainable Homes: Technical Guide, Department for Communities and Local Government, April 2008;

[4] Nicol, F. and McCartney, K. (2001) Smart Controls and Thermal Comfort (SCATs), final report to the European Commission (Contract JOE3-CT97-0066) Oxford Brookes University.

[5] Humphreys, M. A. and Nicol, J. F. (1998) Understanding the Adaptive Approach to Thermal Comfort, ASHRAE Technical Data Bulletin Vol. 14 (1) Field studies of thermal comfort and adaptation (ed. Geschwiler M et al) American Society of Heating Refrigeration and Air­Conditioning Engineers, Atlanta, USA 1998

[6] The Passivhaus standard in European Warm Climates: Design Guidelines for Comfortable Low Energy Homes: Part 2. National proposals in detail: Passivhaus Portugal and Part 3. Comfort, climate and passive strategies, both Edited and compiled by: Brian Ford, Rosa Schiano-Phan and Duan Zhongcheng, School of the Built Environment, University of Nottingham. Download at: http://www. passive-on. org/en/cd. php (accessed Aug 2008).

Advanced Housing Renovation by Solar & Conservation Fritjof Salvesen

Operating Agent for IEA SHC Task 37
KanEnergi AS, Hoffsveien 13, 0275 Oslo, Norway

Abstract

This paper gives an overview presentation of the IEA SHC task 37 “Advanced Housing Renovation by Solar & Conservation”. The task is organized under the IEA Solar Heating and Cooling Programme (SHC) and includes more than 40 experts from 12 countries. The task started in 2006 and will end in December 2009.

The objective of this Task is to develop a solid knowledge base how to renovate housing to a very high energy standard while providing superior comfort and sustainability. The task will also develop strategies which support market penetration of such renovations explicitly directed towards market segments with high renovation and multipliable potentials. The technical R&D and the market implementation activities are equal priority areas.

Keywords: Housing renovation, IEA SHC, EuroSun2008

1. Introduction

Buildings are responsible for up to 35 percent of the total energy consumption in many IEA countries. And, housing is the largest energy consumer in the building sector. When houses are renovated to meet contemporary expectations and lifestyles or to repair existing construction, there is the opportunity to reduce the building’s energy use often at marginal extra costs.

Many exemplary renovation projects have been completed, but the experience gained has not been systematically analyzed and many projects are at best only locally known. Because most property owners are not even aware how far energy demand can be economically reduced, they too often set mediocre goals. This is a missed opportunity to prepare buildings for the future energy era.

image495To address this void, the IEA SHC Programme’s Task 37: “Advanced Housing Renovation with Solar & Conservation” is working to develop a solid knowledge base on how to renovate houses to a very high energy standard and to develop strategies that support the market penetration of these renovations. SHC Task 37 is analyzing and will publicize the results of many successful renovation projects. Based on this analysis, innovative concepts will be identified and further developed for the most important housing market segments. The global environmental impact of such solutions will also be examined.

The Task started in July 2006 and will be finished by the end of 2009.

1

image496The task has more than 40 experts from Austria, Belgium, Canada, Denmark, Finland, Germany, Italy, the Netherlands, Norway, New Zealand, Sweden and Switzerland.

The objective of the Task is to

• develop a solid knowledge base how to renovate housing to a very high energy standard while providing superior comfort and sustainability

• develop strategies which support market penetration of such renovations explicitly directed towards market segments with high renovation and multipliable potentials

The technical R&D and the market implementation activities are equal priority areas.

2. Status and results

The work is organized in four subtasks, and a short description and status is presented below

A. Marketing and Communication Strategies

This Subtask is analyzing the building stock in order to identify building segments with the greatest multiplication and energy saving potential. Examples of building segments are year of construction, type of buildings, type of envelope and components. Within these segments important topics for discussions are: — ownership and decision structures, inhabitants and their characteristics and actual groups of retrofit market players.

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Building stock analysis has been completed in several countries and these will be the basis for a cross country summary report. In parallel the experts are working on the content of the coming report “Business Opportunities in Advanced Renovation”.

Figure 1 Example from the building stock analyses in Norway

B. Advanced Projects Analysis

The analysis of successful renovation projects is underway and experts have agreed upon a set of criteria for selecting demonstration projects.

10th October, Lisbon — Portugal *

Occupancy

types:

All forms of housing including mix uses

Concept:

Something innovative enough for international publication.

Energy:

Max primary energy for space heating and associated technical installations (fans, pumps, etc.): 60 kWh/m2.

Opaque envelope insulation < 0,25 W/m2K (if possible, should not exclude special buildings, for example, historical buildings).

Economics:

Marketable solutions

Design:

Substantial improved living quality.

Table 1: Criteria for selecting demonstration projects

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Several exemplary renovation projects have be selected from most of the participating countries. A standard reporting format and units are used to allow cross comparisons. The objective is to characterize the renovation process, motivations, benefits and opportunities for improvement.

Figure 2 Example brochures of exemplary buildings

A number of brochures are available from the task 37 web-site www. iea-shc. org/task37

These brochures show a dramatic reduction in the demand for heat, up to 95%. Twelve task 37 demo-projects show energy reductions from 62 to 95%, with the average 75%.

C. Analysis and Concepts

Drawing on the market analyses for subtask A and the exemplary projects from subtask B, in this subtask concept packages will be identified and analysed to maximize their life cycle benefit/cost ration. The work will draw on simulations, monitoring of in-place applications and feedback from the industry. Details of solutions, design advice and examples of phased, compatible renovation measures will be reported.

The experts are working on different aspects, and among these are

• whole building concepts

• thermal bridge recommendations

• monitoring of built housing renovations

D. Environmental Impact Assessment

Подпись: The building sector is responsible; to a great extend, in the environmental impacts: • 45% of energy consumed • 40% of produced waste • 50% of tapped natural resources • 30% of greenhouse gas emissions; • 16% of drinkable water consumption In subtask D the environmental impacts of a sample of renovation projects will be assessed.

Factors such as: CO2, water, waste, materials flow, use of urban space and health as well as social consequences will be considered. Life cycle analyses will be carried out in the full range of scales from components to urban neighborhoods.

Subtask D will produce a booklet on Sustainable Renovation Basics. The draft report is expected to be ready by this autumn.

Solar Energy Influence on the Energy Balance of Attic Rooms

D. Chwieduk

Inst. of Fundamental Technological Research Polish Academy of Sciences, Swietokrzyska 21, Warsaw, Poland
Institute of Heating Engineering, Warsaw University of Technology, Nowowiejska 21/25, Warsaw, Poland

dchwied@ippt. gov. pl

Abstract

Nowadays, attic apartments with inclined external walls and windows (roof) surfaces have become quite “fashionable” in buildings erected in highly densely populated cities. The influence of solar energy and in consequence energy transfer through windows on the energy balance of such rooms is evident. Calculations of solar radiation incident on building surfaces, including attic envelope have been performed. To describe and solve problems of the dynamics of processes in the building envelope and surrounding, a mathematical model of energy transfer phenomena in opaque and transparent elements has been developed. The developed model enables to calculate energy transferred through windows into/out of the room at any time, and other energy balance elements, including heating/cooling energy needs. Selected results of simulation studies of attic rooms are presented. It turns out that overheating in summer due to high solar irradiation and energy transmitted and absorbed in glazing can be a real problem for rooms in attics.

Keywords: energy transfer through windows, energy balance of a room, rooms at attics

1. Introduction

Analysis of solar energy availability and its influence on the energy balance of attic rooms is the subject of this paper. Nowadays, when a building envelope is designed and constructed according to energy savings measures, with high quality of thermal insulation and other building materials, the heat transfer through the opaque external walls is a minor part in the total energy transport between the outdoor and indoor environment. Important elements of the energy balance of a building are the energy transfer through windows and energy needed for ventilation (supplied with or parallel to fresh air), even if recuperation of waste heat (from ventilation) is accomplished. Energy transfer through windows is especially important for rooms in attics.

Nowadays, attic apartments with inclined external walls and windows (roof) surfaces have become quite “fashionable” in buildings erected in highly densely populated cities. In many cities because of the high costs of land, especially in the city centres (downtowns), developers and construction companies construct buildings using every available square meter of land. If it is not possible to build high buildings because of existing spatial management plan of some regions of the city, then very often the last floor, at attics, is used as living space. However, it is against traditional way of the use of buildings. For many years in the past attics were used as stores and buffer zones, but not as apartment spaces. The living comfort at attics is not as good as at rooms located on floors below attics. The living standard can not be comfortable if no extra protection especially against too much solar radiation in summer is implemented. The problem of overheating of rooms at attics with special location (orientation), because of too much energy transfer through windows, is the main topic of this paper and problem to be presented.

Summer thermal behaviour

Подпись: Solar Time (hs) ♦ Meetings Room о Doctor's Offices 4 and 5 д Doctor's Offices 1 to 3 —n—North Corridor —Ж— Outdoor Подпись: Solar Time (hs) • Access д South corridor —о— Laboratory —ж— Outdoor

A similar analysis was performed for both building sectors in a typical summer day. In the simulations, the openings added in the Health sector were considered closed, and the air chamber added in the Development sector was ventilated to avoid overheating. The thermal behaviour of the Health sector in summer (Figure 8) shows that, during the sunshine hours, the indoor air temperatures are around 30 °С with an average outdoor temperature of 22.9 °С. Only during the night the building enters inside the comfort zone. In the Development sector the mean air temperature is around 26 °С (Figure 9) with a mean outdoor temperature of 22.9°C..

Подпись: (b)(a)

Fig. 8. Summer hourly temperature in the Health Sector: (a) North thermal zones, and (b) South thermal

zones.

In this sector, the indoor temperature, even without internal gains, is always greater than the outdoor temperature. In the afternoon, the west windows cause glare and dazzling, because the sunlight incides on the corridor floor from 14PM to 16PM and on the internal wall connecting the corridor with classrooms and services since 14PM to sundown

In both sectors of the building, natural ventilation and ceiling fans are suggested. Aeolian extractors in the ceilings are suggested to remove the warm air. In the Health sector, the crossed ventilation cannot be practiced because of the location of the offices in the center of the building. In summer, when the sun exposition of walls should be minimized, the East and West envelopes of the Development sector are highly exposed. In addition, solar radiation from West will cause overheating and glare in the afternoon, so shading devices are imperative for glazed areas.

4. Conclusions

The improvements to the original design of the CIC building showed to be effective to reduce the heating and cooling loads and to obtain important energy-saving. The strategies to be applied were selected after a careful analysis of the thermal behaviour of the original design, that evidenced an uncomfortable indoor conditions in the Development Sector both in winter and summer: in winter, when high levels of solar collection are needed, this Sector only collects direct solar radiation from East and partially from West, due to the shading of neighbouring buildings; in summer, when direct solar radiation must be avoided, the Sector is unshaded and collecting both from East and West. Furthermore, in the afternoon, the west windows cause glare and increase overheating. The winter thermal behaviour of the Health Sector is better due to the high solar collection in North surfaces.

Some strategies were tested to improve the thermal behaviour of the building. Thus, to heat the offices of the Health sector in winter, the use of openings (1% of the wall area) connecting the North corridor and the offices was added, in order to introduce the hot air into the offices by natural convection. The openings must be closed during the night to prevent inverse air flow. In the Development sector, the addition of a tight air chamber in the roof (with ventilation in summer) was recommended.

In both sectors of the building, natural ventilation and ceiling fans are suggested for the summer period. The installation of aeolian extractors in the ceilings is proposed in order to remove the

warm air. The extractors can remove the warm air during the night. In the Health sector, the crossed ventilation cannot be practiced because of the location of the offices in the center of the building. In summer, when the sun exposition of walls should be minimized, the East and West envelopes of the Development sector are highly exposed. In addition, solar radiation from West will cause overheating and glare in the afternoon, so shading devices are imperative for windows and glazed areas.

It is expected that this project will serve as a demonstrative project, in order to to spread the application of passive strategies and solar equipment in public buildings of social use, and to minimize the impacts on the climate and the environment caused by the consumption of conventional energy. Also the training of professionals and design technicians of the Social Development Ministry, and the training of the people belonging to the cooperative work societies of Villa Zagala CICs in subjects like management, operation and control of CICs buildings is expected.

Aknowledgements

This project was partially supported by PAE (ex PAV) 22559, CIUNSa 1699, PICTO UNSa 36646, and the special project “Mejoramiento de la Envolvente y Equipamiento Solar con Fines Demostrativos y de Capacitacion para un Centro Integrador Comunitario (CIC) del Ministerio de Desarrollo Social en Villa Zagala — Partido de Gral. San Martin, Provincia de Buenos Aires”. SECYT.

References

[1] Righini R., Grossi Gallegos H., Raichijk C., (2004). Trazado de nuevas cartas de irradiacion solar global para Argentina a partir de horas de brillo solar (heliofania). Energias Renovables y Medio Ambiente, 14, 23-32.

[2] Hernandez A., (2003), Geosol: Una Herramienta Computacional Para el Calculo de Coordenadas Solares y la Estimacion de Irradiacion Solar Horaria, Avances en Energias Renovables y Medio Ambiente 7, 19 — 24.

[3] Flores Larsen S., Lesino G. A new code for the hour-by-hour thermal behaviour simulation of buildings. In: Proceedings of VII International Building Simulation Congress 2001, Rio de Janeiro, Brazil, 75-82.

[4] Flores Larsen S., Lesino G. Programa de diseno y simulacion de edificios. In: Proceedings of XI

Congresso Iberico e VIIbero-Americano de Energia Solar, Vilamoura, Portugal, 2002.

[5] LuzSol 1.1. http://www. labeee. ufsc. br/software/luzDoSol. html. Last accessed: July 29, 2008.

Solar Blox

The assignment of this project was to design an autonomous PV system for beach cabins. The main criterion for the design was ease of use and ease of transport, since beach cabins are installed and de-installed once a year. The final design consists of different modules. Each module has a different function, ranging from battery, to charge regulator, to radio. A consumer can thus compose his/her own PV solar energy system. The connected Solar Blox form one console with a straightforward user interface in the cabin, instead of a collection of loose components. The use of modules facilitates transport of the system and installation of the system. And since the Solar Blox are specifically designed to be connected to each other, the consumer can be assured that the components are well matched together, thereby improving the reliability of the system.

Solar Blox are not limited for use in beach cabins. During the projects also in other markets (export) were considered for such a product. An order for a Solar Blox based PV system was already placed.

image465

Fig. 8. Solar Blox modules in different combinations.

Economy and Plant size

General statements regarding the economy of solar plants are very difficult to make as the reference cost of electricity varies by a factor of 5 worldwide and the efficiency of electrical cooling machines also varies. Solar radiation varies by a factor of approx. 2 between the various Locations we have measured, and additional use of the energy from the solar plant for heating and hot water purposes has to be individually assessed for each project. Grant assistance available for such projects also varies considerably.

However, it can be assumed that most of the projects will achieve a payback period of 5-15 years based on current energy prices. It is important to note that there is a minimum size for solar cooling

image506

plants to be economic. This depends on location and certain conditions, and varies between 1000m2 — 2000m2 of area to be cooled for now.

Diagram 8: Energy Cabin for cooling and heating with solar energy.