Within the “Solar Jails” programme, two solar thermal plants have been installed yet. They are operating respectively into the Jail of Rebibbia (Rome) since 2002, and into the Jail of Terni (about 120 km north of Rome) since summer 2008.

In the framework of the first “Solar Jail” project, 96 flat — plate solar thermal collectors have been installed with a total useful area of 250 m2 (175 kWth) in order to contribute to the preparation of 18,000 l/day of DHW at 45 °C, for 400 prisoners. The plant, designed to perform a solar fraction of about 60% of the DHW annual demand, was installed with the support of 10 prisoners previously trained on solar thermal. Currently, prisoners are also involved in maintenance and in data acquisition.

Thanks to this first pilot experience, many of the problems faced during either the system operation or the implementation of the general procedures have been already solved, and several improvements carried out in the second phase of the programme.

Concerning the new plant in Terni, 60 flat — plate solar thermal collectors have been installed with a total useful area of 156 m2 (109 kWth).

The average daily consumption of 350 users is around 13,500 l/day, at 40 °C. The solar thermal system is expected to supply the 70% of the estimated total annual energy request, that is 208 MWh per year. Therefore, the annual solar output foreseen is about 146 MWh.

The plant is endowed of a monitoring system for gathering all the parameters needed to control the energy performances of the plant, the operating temperatures and the achievement of the solar results. Furthermore, in the next future, it might be possible to store the data collected (in different sites) in a central database.

A second plant is now under construction in Rebibbia Jail, where 180 m2 (126 kWth) flat — plate thermal collectors are expected to deliver 110 MWh per year to 396 prisoners. Five more systems are foreseen to be carried out within the 2009 in Florence, Turin, Laureana di Borrello (Reggio Calabria), Viterbo and Velletri (Rome).

3. Conclusions

Jails, not only in Italy, are usually located in buildings with large surfaces suitable for installation and without strict aesthetical requirements for the architectonic integration. Those characteristics, coupled with the very high and continuous annual DHW energy demand, show clearly the huge potential for the repeatability of this initiative.

The main outputs expected by the completion of this phase of the “Solar Jails” programme are:

• empowerment and new reemployment opportunities for about 250 prisoners trained as solar thermal

installers;

• 15 new large scale solar thermal plants, i. e. up to 3,750 m2 (2.6 MWth) of solar thermal collectors

installed;

• energy costs savings for jails to be reinvested in activities and infrastructures;

• staff of public technical departments skilled in solar thermal to secure the project durability and to act

as multiplier in other public buildings;

• improvement of knowledge on the behaviour of solar thermal plants.

References

[1] A. Corrado, R. Battisti, A. Micangeli, (2002), Large Scale Solar Thermal Plant For Domestic Hot Water In The Italian Rebibbia Jail, Proceedings of the EuroSun 2002 Conference, 23 — 26 June 2002, Bologna, Italy

The Riverhouse at Rockefeller Park is a USGBC LEED Gold building located at the combined sites of 16 and 17 in Battery Park City. This project would result in one of the fiercest trade battles in the fledgling New York City PV industry. Designed with the trade considerations known on other projects, the architects wanted the PV to work as louvers at the top of the building. The PV system was designed to be a louver system since zoning rules required that a very light and transparent look be adopted at the top of the building. These louvers evolved into glass/glass laminates and eventually into a tracking PV system on the east, south and west facades of the building’s tower, the first of its kind in the United States. The fact that the BIPV modules were considered louvers meant that the Sheet Metal Workers Union would get the job of installing the panels. Although the install got off to a good start and was proceeding quickly, the IBEW took issue with the installation midway through its construction. The electrical union claimed that since the PV panels were technically electrical fixtures, all installation of these panels should be completed by Electricians, including the hanging and setting of the louvers, a job typically performed by Sheet Metal Workers. The issue went all the way to a national arbitration hearing in Washington DC where the IBEW defeated all other trades to claim this particular installation. Since this was a one off decision however, it remains to be seen what trade union will get work of this type on the next project. The decision at the national arbitration set a further precedent. It was clear before the ruling that Electricians should install UL Listed PV products. However, after the ruling, even the non-UL-listed BIPV products could be legitimately claimed by Electricians leaving it unclear whether Electricians would try to claim BIPV panel installation on all future projects. Two smaller systems of glass/glass laminates echo the top of the tower on the west wing penthouse; these modules were eventually fixed and installed by a composite crew of Electricians and Ornamental Ironworkers.

J. Cipriano1*, C. Lodi2, D. Chemisana3, G. Houzeaux4, O. Perpinan5

1 CIMNE-BEEGroup, Building Energy and Environment Group. International Centre for Numerical Methods in

Engineering. Dr. Ulles n° 2. 3°. 08224. Terrassa. Spain.

2 University of Lleida (UdL). CIMNE-MACS Clarssroom. Pere de Cabrera s/n. CREA Building. Cappont

Campus. 25001. Lleida. Spain

3University of Lleida (UdL). Solar Energy and Building Physics Group. Pere de Cabrera s/n. CREA Building.

Cappont Campus. 25001. Lleida. Spain

^Barcelona Supercomputing Centre (BSC-CNC)- Department of Computer Applications in e-Science &
Engineering. Nexus II Building. Jordi Girona, 29. 08034 Barcelona. Spain.

5ISOFOTON — Montalban, 9. 28014 Madrid.

Jordi Cipriano, eipriano@,cimne. upc. edu

Abstract

This research aims at developing new standardized typologies of semitransparent double skin fa? ades formed by PV laminates in the outer skin. At present there are many buildings in Europe which incorporate such active fa? ades, but all have been designed as user defined projects and very few accurately evaluate the feasibility of using the heat produced within the air gap. There is actually a lack of effective methodology to allow non-specialist architects to design and evaluate such fa? ades. This research tries to address this situation: the Spanish PV manufacturer ISOFOTON, together with the partners of the PVTBUILDING project: CIMNE, the UdL, PICH — Aguilera, DOMUS and BSC have begun a collaboration to design industrialized modules constituted by an external semitransparent PV layer, a wide air gap and an internal glass layer. This paper describes the results of four stages of a more wide research: a detailed analysis of the existing double skin fa? ades in office buildings and the definition of a family of standard PV modules and ventilated fa? ades; an intensive evaluation of the existing heat transfer relations for asymmetrical heated vertical air channels; the programming of a dynamic transient solver based on TRNSYS and the validation of the codes with the set up of prototypes and the beginning of an experimental campaign.

Keywords: PV/Thermal, ventilated double skin fa? ades, heat recovering

1. Introduction

In recent years many authors have been working in the field of double skin ventilated fa? ades. Since the 1990’s the Joint Research Centre has been carrying out an intensive characterization of PV ventilated fa? ades, with and without ventilated air gaps. Some European funded projects have been actively supporting this work, PASSLINK, PV-HYBRIDPAS and IMPACT [18]. Between 1999 and 2000, the Centre for Applied Research at the University of Applied Sciences Of Stuttgart [7,11] undertook the theoretical analysis and monitoring of the Mataro’s public library building, which had the first PV ventilated fa? ade in Europe. More recently, the treatment of the induced flow and the heat transfer at the air gap and the surfaces of a natural ventilated double skin fa? ade has been progressively refined by Brinkworth [3,4]. Concerning to the mathematical model to define the energy performance
of such fa? ades, sophisticated models for double skin fa? ades were developed by Saelens [15]. Although these detailed studies have lead to an increase in the knowledge of the heat transfer processes, there are still many unclear fields such as: the convective heat transfer coefficients definition; the evaluation of the direct solar radiation absorbed by the solid parts; the evaluation of the mass flow rate in non-developing turbulent flows and, the coupling with the HVAC systems.

Concerning to the dissemination of the PV ventilated fa? ades, many recent newly constructed office buildings have included such devices in their designs; however, the spread of this technology has not occurred at the necessary scale. One of the reasons, we believe, has to do with the lack of standardised designs which forces the designers to select the glass transparent surfaces and the support structures separately from the PV laminates, leading to fitting problems and size incompatibilities.

The roof is intersected by the two beams that create a central axis, which rises towards the altar in a counter-movement to the sloping floor.

It emphasizes the vertical focus related to the purpose of the place and incorporates south-facing daylighting that accentuates the procession from the entrance to the altar.

The remaining two parts of the roof on either side of the central beams consist of a saw-tooth shed steel construction which further to permitting the use of daylight, functions as a structural element that frees the hall from vertical supports. The south-facing inclined surfaces of the sheds serve

both to reflect daylight towards the north-facing clerestory strip windows and to support 3,200m2 of photovoltaic panels.

A translucent membrane is hung below the shed in order to avoid that it be visible from below and in order to create an overall soft distribution of both day — and artificial lighting. The uniformity or accentuation of day — or artificial lighting in different areas of the interior space can be computer controlled by closing or opening light directing blinds that are fixed to the clerestory glazing and by turning on indirect artificial lighting when desirable.

Elaborate scientific simulations were undertaken for the optimisation of the bioclimatic design and daylighting features of the building resulting in considerable energy savings.

3. Materials

The interior space with its simple materials stresses the monolithic and contemplative character of the structure. Interior walls are white, clad with wood up to a certain height. The central beams are of white fair-faced concrete.

Concluding the development aims at providing a synthesis of the unique historic pilgrimage place of Fatima and the new Church with all its present-day requirements in a way that enhances the old, the new and the eternal.

4. Credits

The following were involved in the project:

Project architects: Alexandras N. Tombazis and Associates Architects, Athens, Greece Project architect: Alexandras N. Tombazis

Project team: Stavros Gyftopoulos, architect in charge, Sophia Paraskevopoulou, competition phase

Architectural design and coordination in Portugal: Paula Santos Arquitectos, Lda., Paula Santos, Joana Delgado

Structural design, security and hygiene planning: Eteclda — Escritorio Tecnico de Engenharia Civil, Lda.

Mechanical engineers: Edificios Saudaveis — Consultoria, Lda.

Sanitary and sewage engineers: Vitor Abrantes — Consultoria e Projectos de Engenharia, Lda.

Electrical engineers: OHM — E, Gabinete de Engenharia Electrotecrnca, Lda.

Landscape design: Proap — Lda. — Estudos e Projectos de Arquitectura Paisagistica, Lda.

Acoustics and electroacoustics design: Vitor Abrantes — Consultoria e Projectos de Engenharia / SOPSEC, Lda. / LPL, Lda.

Energy consultants: University of Athens, Department of Applied Physics, Prof. M. Santamouris, Athens, Greece

Natural and artificial lighting: Bartenbach Lichtlabor GmbH, Aldrans, Austria Acoustics consultants: C. S.T. B., Marne la Vallee, France.

In general, the recommendations for energy efficiency in this household were as follows [3]:

• Repair of the freezer & fridge-freezer that had faulty thermostats. Installation of a timer switch would also help remedy this fault, if the thermostat cannot be replaced. Estimated electricity savings would amount to 12%. The purchase of new, more energy efficient appliances is another option.

• Use of air-conditioning units for heating in winter rather than electric filament heaters.

• Water consumption — replace washing machine with Class A machine. Change habit of washing patios with free flowing water (Estimated water savings: 40%).

• Appliances in stand-by mode — Switch off appliances that are rarely used (Estimated electricity savings: 7%).

• Install more energy saving bulbs.

For the SWH system, the recommendations were the following:

• Due to the evidence of rusting of the solar tank and some water leakages, one would recommend the eventual replacement of this SWH with two units. The first would be dedicated to the bathrooms; the second would supply the washing machine and the kitchen, thus reducing the amount of water to be heated by the electric backup heater.

• An electrical timer should be installed on every back-up electric element of solar heaters. This would avoid unnecessary heating and was proven to save approximately 12% of the electricity bill over the measured period.

• Clothes should ideally be washed later on in the day; by which time the SWH would have absorbed sufficient solar energy.

• Good insulation on all hot water pipes was also recommended.

One of the salient overall conclusions that may be drawn from this exercise was that the installation of RE systems was, in itself insufficient to ensure energy savings and user satisfaction. A good understanding of the requirements and the lifestyle of consumers planning to install such systems is paramount, to ensure that systems are adequately sized to meet the demands on a case-by-case basis. On the other hand, people using such systems should be aware of the basic operational characteristics, in order to adapt their lifestyles in a way that will give them the full benefits of a renewable resource.

2. Acknowledgements

The authors wish to acknowledge the opportunity given by the homeowners to carry out a detailed energy audit for their home.

References

[1] Enemalta Corporation (2008), Private Communication with Enemalta Corporation, Marsa, Malta.

[2] National Statistics Office (2008), Energy Consumption in Malta 2000-2007, NSO News Release No. 91/2008, 22 May 2008, http://www. nso. gov. mt/statdoc/document file. aspx? id=2244, National Statistics Office, Library & Information Unit, Lascaris, Valletta VLT 2000, , Malta.

[3] M. Villameriel Tejedor (2008), Energy Study at a Residence in Malta, unpublished Final-Year Industrial Engineering Dissertation, Institute for Energy Technology, University of Malta, Malta, in collaboration with Valladolid University, Spain under the Erasmus student-exchange European Programme 2007/08.

[4] M. Krarti (2000), Energy Audit of Building Systems — An Engineering Approach, ISBN 0-8493-9587-9, CRC Press LLC, U. S.A.

[5] S. P. Borg, C. Yousif & R. N. Farrugia (2005), Investigation of Domestic Solar Water Heating Installations in Malta, “Renewable Energies in Malta and Beyond” Seminar, 19 September 2005, Salina, Malta, published by the Institute for Energy Technology, University of Malta, Malta.

[6] J. Gordon (Editor, 2001), Solar Energy: The State of the Art, ISES Position Papers, ISBN 1-902916-23-9, James & James Science Publishers Ltd.

The indoor climate requirements in the exhibition rooms are very high due to the conservation of the art objects. Temperature and relative humidity are only allowed to change in a very small

margin (20 — 22 C, 50 — 55 %). Therefore it is necessary to treat the supply air in summer (de­humidification) as well as in winter (humidification). This requires a large amount of energy which should be reduced within this project.

During winter a contact humidifier humidifies the incoming air. The energy demand for vaporization is extracted from the air itself. It is not provided by means of electric energy as in a steam humidifier. The air is heated to approximately 30° C so that it can be supplied to the rooms at about 22° C. A rotating air-to-air heat and humidity exchanger with a heat recovery coefficient of 80 % and a humidity recovery coefficient of 50 % is used for the heat and humidity recovery during winter time. In summer the air is de-humidified by cooling the air to the dew point (8 to 9° C) followed by re-heating to 16 to 18° C by waste heat from the cooling system.

To supply the required cold-water temperatures (6 to 8° C) a chiller is needed. The use of environmental cold extracted from the ground — like it is used for heat removal by ceiling-panel cooling — for the de-humidification process is not possible. In summer, a great part of the air (app. 70 %) is recirculated to reduce the de-humidification volume. The proportion of external air is controlled by CO2-sensors located in the exhibition rooms.

The main component to supply cooling and heating is an absorption chiller that is used as a heat pump in winter. It uses low level heat from the soil around 73 foundation piles, connected by a circulating water supply, in winter and is driven by heat from 47 CPC evacuated tube collectors with a total output of 100 kW in summer. If the output from the collector field is insufficient, a wood pellet combustion unit with four boilers and a total output of 128 kW drives the absorption chiller. For each unit of heat from the boilers the heat pump produces 1.7 units of usable heat. 40% of the heat in the heat pump operation mode comes from the soil.

In summer, medium temperature cold (15-18° C) is sourced directly from the foundation piles. A total of 65% of the overall cooling requirement can be gained from the ground. The absorption chiller provides the cold needed for the air conditioning. The solar collector field produces about 80 % of the required heat for the absorption chiller. For peak load and backup a common compression chiller is used.

3. Monitoring

The building is monitored intensely since October 2006 within the research program EnOB (see www. enob. info). A total of 500 data points is recorded continuously. The results are transmitted via ISDN to the Building Science Group at the University of Karlsruhe where the analysis, the calculation of characteristic values and the comparison with the planned performance is done. It is also possible to use information, gained from the evaluation of the data, for optimizing the building performance. The following values are quantified:

• energy flux (heat, cold, electricity)

• temperatures in the technical systems (HVAC)

• temperatures inside the rooms

• humidity inside the rooms

• flow rate of the ventilation

• position of valves

• runtime and speed of pumps

• switching status (on/off)

• consumption of pellets

• solar radiation

The data can be used for example to calculate the COP of the absorption chiller or the efficiency of the ventilation system. The compliance of temperature and humidity values with the requirements is also monitored. Global characteristics, like energy and primary energy consumption per square meter, serve as a base to classify the building.

Primary energy consumption was 77 kWh/(m2NFAa) (Rislerstrasse KfW60), 69 kWh/(m2NFAa) (Rislerstrasse KfW40), 51.8 kWh/(m2NFAa) (Freyastr) and 37 kWh/(m2NFAa) (Blaue Heimat) applying the credit method for CHP in the latter case. Thus the results are slightly above the target.

Energy consumption KfW40 2005/06 [kWfVrr^a]

80 70 60 50 40 30 20 10 0

Useful energy Site energy Primary energy

■ Heating DHW ■ Solar Auxiliary energy ■ Ventilation

Energy consumption KIW60 2005/06 [kWfv’nrVa]

The results allow the following conclusions to be drawn about the buildings and their energy

concepts:

• Energy: the targets projected during planning were reached in actual operation and even surpassed in some cases. The building standards studied can be considered state of the art even by today’s standards. Renovation can bring old buildings close to the passive house standard despite specific problems, such as ventilation, air tightness, and thermal bridges. The strict standard for the building itself means that parameters influenced by users (such as hot water consumption and ventilation) become more important, as do relatively minor energy flows (such as distribution and storage losses), which then have to be taken into greater consideration during planning. The main consumption parameters are hot water and electricity; for instance, the figures for Blaue Heimat were: heating: 18.9 kWh/(m2NFAa), hot water: 28.4 kWh/(m2NFAa), electricity: 24.3 kWh/(m2NFAa). Even though they were taken into consideration during planning, storage and distribution losses were almost half as high as the actual heating energy consumption (insulation of the distribution system in Blaue Heimat: 200 %, Rislerstrasse: installation in attic insulation)

• Supply Systems: thermal solar collectors make a significant contribution. If storage is properly dimensioned, a cogeneration unit can run at very high capacity utilization rates, thereby functioning as an efficient supply system after renovation and being an important part of a net zero energy strategy.

• Users: A comparison of heating energy consumption in the buildings in Rislerstrasse revealed only a slight difference between the two energy standards, which was not projected. The reasons may be the influence of user behaviour (comfort requirements and ventilation), a difference in the number of people in the buildings, or less efficient heat recovery in the ventilation system.

This assessment and analysis as part of IEA SHC TASK 37 received funding from the German

Ministry of Economics and Technology — BMWi (reference number: BMWi 0327271B).

References

[1] Salvesen, F. : Advanced Renovation with Solar and Conservation, Proc. of EUROSUN 2008, Lisbon

[2] Hastings, R. : Advanced Solar Renovation, Keynote at EUROSUN 2008, Lisbon, www. iea-task37.org

[3] Voss; K., Kramp, M.: Zero-Energy/Emission-Building: Terms, Definitions and Building Practice, CESB Conference, Prague, 24.-25. September 2007, proceedings vol. 2, p. 547ff

[4] Projektrager Julich: www. enob. info

[5] Deutsche Energieagentur dena: www. neh-im-bestand. de (in German)

[6] Reiss, J.; Erhorn, H.: Bauliche Konzeptentwicklung fur eine 3-Liter-Reihenhauszeile im Rahmen von ModernisierungsmaBnahmen in Mannheim-Gartenstadt. Bauphysik 26 (2004), Heft 6, p. 322-334

[7] Ufheil, M.; Sanierung Blaue Heimat, 9. Passivhaustagung Ludwigshafen (in German)

[8] Zaman, A.: Passivhaus im Bestand Hoheloogstr. 10. Passivhaustagung Hannover 2006 (in German)

[9] Kagerer, F.; Herkel, S.: Versorgungsstrategien in der Wohnbausanierung, OTTI Tagung Sanierung 14.2.2008 (in German)

[10] Schmidt, M.; Schmidt, S.; Treiber, M.; Arold, J.: Schlussbericht „Energetische Modernisierung kleiner Wohngebaude auf 3-Liter-Haus-Niveau in Mannheim“, Lehrstuhl Klimatechnik, Uni Stuttgart, 2007

The second experiment was carried out on three typical late-spring days in the beginning of May. In the case of late spring experiments all of the system actuators were active and the set-point temperatures were set in the rage from 15 °C to 25 °C, depending on the time of day. The experiment was designed to test the ability of the fuzzy controller to follow the temperature set-point profile and at the same time to prevent the test cell from overheating. Cooling of the test cell was achieved by combining the movable shading and the ventilation induced by the ventilator imbedded in the wall of the cell. The thermal control algorithm regulated the functioning of the roller blind, heater and ventilator with the aid of PID/V controllers. In the control system the roller blind positioning had a priority. If after a limited time the desired indoor temperature was not achieved, the heater or the ventilator were activated.

Weather conditions during the first two days were constant and almost identical. On the last day a change in weather pattern is evident as the levels of direct solar radiation as well as external air temperatures have dropped. During the first two days solar radiation reached peak levels of 800 W/m2 and the temperatures were in the range from 13 °C in the morning to 30 °C in the early afternoon. On the third day in the beginning of the afternoon the weather changed, which is signified by a drastic drop in solar radiation levels as well as in the external air temperatures. From this point on there was no more need for cooling of the cell, and heater had to be activated to reach the desired internal air temperatures. Thermal fuzzy controller was able to cool the test cell during the first two days as, maximum internal temperatures at any given time did not exceed 27 °C, which were 2 K above the set­point temperature and approximately 3 K below maximum external air temperatures. The experiment also showed that only shading would not be able to achieve satisfactory results, as the ventilator had to be turned on almost throughout the day and most of the night (Fig. 3.). We can speculate that if a ventilator with a lager volume capacity was installed, even beater results could be achieved with the application of natural ventilation during night-time.

3. Conclusion

Experimental test cell with the appropriate controller and measuring equipment was built with the aim to form a fuzzy logic control system for the regulation of internal thermal and optical environmental conditions. The final goal of the control system was the formulation of regulation rules, which would enable harmonious control of thermal and illumination processes in the built environment. The reaction of the test chamber to the illuminance and thermal conditions was regulated by positioning

the externally fixed roller blind and with additional heaters and ventilator. The objective of the system was the optimization of use of the available environmental conditions, especially focusing on the external air temperature and solar radiation. The controller’s algorithm was composed of two separate loops, one for the illuminance and the other for the thermal regulation. In experiments presented in this paper only the thermal loop was used, as the focus of the conducted tests was on the study of cooling load reduction with automated shading. The executed tests confirmed the initial assumption that during mid-seasons properly regulated shading devices can reduce or in some cases eliminate the need for

cooling of internal living and working environments. Because of human adaptation to thermal environments manual regulation can not provide the same precision and efficiency as the automated regulation.

The experiments showed that the fuzzy controller was able to consistently keep internal temperatures in the test cell lower in comparison to the external thermal conditions. Compared to the experiments when the cell was not automatically regulated (e. g. roller blind was left open) the fuzzy system was able to substantially reduce cooling loads in the cell. Additionally, the thermal fuzzy controller was also able to follow the internal set-point profile within the acceptable margin of error. Internal air temperatures in the cell were kept in the acceptable range around the set-point profile even in times of high external air temperatures and clear sunny weather with high solar radiation. Even better results for cooling load reduction during mid-seasons could be attained if the automated shading was used in combination with natural ventilation. Use of natural ventilation is especially effective during night­time when the interior environment can be passively cooled as external air temperatures are lower than internal.

References

[1] A. Kramer, Building Science and Environment-Conscious, Design Module 1: Design Principles, 7 Toward Smart Buildings, European Commission TEMPUS Joint European Project JEP-1802, 1993.

[2] R. Kladnik, A. Krainer, R Perdan, Light and thermal energy coordination in building, Proceedings, Vol. 1., PLEA 1997 KUSHIRO: the 14th International Conference on Passive and Law Energy Architecture, Tokyo, (1997) 59-64.

[3] M. Trobec-Lah, (2003): Harmonizacija toplotnih in svetlobnih tokov z uporabo mehke logike. Doctor thesis. Ljubljana: University of Ljubljana, Faculty of Civil and Geodetic Engineering.

[4] M. Trobec-Lah, B. Zupancic, A. Krainer, Fuzzy control of illumination and temperature comfort in a test chamber. Building and Environment, 40 (2005) 1626-1637.

[5] B. Furlan, A. Krainer, I. Skrjanc, B. Zupancic, Mathematical modelling of dynamical response of the building with variable geometry of openings, Proceedings, ISES-Europe Solar Congress, Portoroz, (1999) II.2.9-1- II.2.9-8.

[6] I. Skrjanc, B. Zupancic, B. Furlan, A. Krainer, Theoretical and experimental fuzzy modeling of building thermal dynamic response. Building and Environment, 36 (2001) 1023-1038.

[7] Z. Kristl, M. Kosir, M. Trobec-Lah, A. Krainer, Fuzzy control system for thermal and visual comfort in building. Renewable energy, 20 (2007) 1-12.

Type of external wall of the building and the extent of its ‘permeability’ for air is just one of the factors which decide about the model and effectiveness of natural ventilation. Its course depends also on the pattern of prevailing winds and their range of speed, number of days without wind, shape and spatial structure of the building, its surroundings and the amplitude of internal and external temperatures. One cannot study the impact of double facades on the ventilation of buildings without taking these factors into account. Every building with its specific shape, location and surroundings, is a unique (and variable over time) aerodynamic object and requires separate and detailed analysis.

The implementation of double facade is directly related, if not subordinated, to the general strategy for forcing air circulation within the building. The right choice of parameters should guarantee that this facade functions correctly for the whole building. Factors which have an essential bearing on the intensity with which air circulates in the building include [10]:

use of materials (type of glass, materials from which sun shades and other non-transparent elements of the facade are made),

• width of the void space created between two layers of the facade,

• area of the cross-section and location of the intake and exhaust air ducts in the external layer and the system which regulates the extent of their opening,

• existing vertical and horizontal barriers in the space between the facade walls,

• system of sunshades — horizontal or vertical,

• techniques for opening windows in the internal layer

• additional aerodynamic elements suspended over the roof and increasing the speed of air circulation inside the facade.

An analysis of the building stock [2] shows that the category ‘terrace dwellings’ built between 1945 and 1975 makes up a major part of the total building stock, both in respect to number of dwellings and energy consumption. In the next decade, these dwellings will be in need of renovation. For these reasons, this type of dwelling is selected as the object for the renovation concepts.

The annual energy consumption of such a dwelling consists of approx. 2.000 m3 of natural gas (for space heating, DHW and cooking) and approx. 3350 kWh of electricity. It is assumed that there is no need for cooling in these dwellings in their current state nor will there be after renovation. In terms of primary energy (denoted with the index p), the total energy consumption adds up to 260 kWhp/m2a, shown by the left bar in the graph in figure 1.

The target of the RIGOUREUS project is to reduce this figure by 75% down to 65 kWhp/m2a. To put this into perspective, in order to obtain the Passive House quality mark, the primary energy consumption of a Passive House must be less than 120 kWhp/m2a. The ambition of the RIGOUREUS project therefore is almost twice as high as the Passive House quality mark.

The middle bar in figure 1 shows the energy demand of a terrace dwelling after the energy demand for space heating has been reduced to 25 kWh/m2a by the application of the Passive House concept and the energy demand for DHW has been reduced by a factor of two by the use of a solar collector. As figure 1 shows, these measures do not suffice to reach the target. The remaining energy consumption is now dominated by the domestic electricity consumption. This too should be reduced by approx. a factor of 4 in order to reach the target of 65 kWhp/m2a, as shown by the right bar in figure 1. In fact, the issue of reducing the domestic electricity consumption is all the more important because in The Netherlands, as in the EU, electricity consumption shows an increasing trend of approx. 2% per year between 1990 and 2006 [3] and it is expected to further increase in the future.