3.1. Occupant satisfaction assessment method

The objective of this study was not the development or the validation of a complex assessment method for occupant satisfaction in office buildings, but rather the identification of weak spots within the described ADS at the LESO-SEB and the discussion of possible ways to deal with these weak spots. We have therefore decided to first roughly check occupant satisfaction with different aspects of their office lighting using a simple questionnaire. As there were only 29 persons working within the building at the time of the study (May and June 2007), the questionnaire had to be easy to understand and quick to fill out in order to maximize the number of returned questionnaires. A simple and reliable questionnaire-based assessment method for occupant satisfaction with office lighting is the Office Lighting Survey (OLS) presented by Eklund and Boyce in 1996 [8]. Many questions within the OLS only allow an answer on a symmetrical, two — stage Yes/No scale. Akashi and Boyce as well as Ramasoot and Fotios have used slightly modified versions of the OLS in 2006 and 2007, respectively [9, 10]. We have adapted the OLS to our specific situation within the LESO solar experimental building and have set up a questionnaire with 12 general, 9 daylighting-specific and 7 artificial lighting-specific statements. Occupants were asked to rate their agreement with each statement on a symmetric answering scale (i. e. without neutral choice) in order to avoid interpretation problems associated with possible neutral choices.

In order to make the questionnaire more sensitive, we have used a four-stage answering scale rather than the two-stage answering scale used within the original OLS. This means that for each statement, occupants had the possibility to answer “yes”, “rather yes”, “rather no” or “no”. These four possible choices were assumed to correspond to 100%, 75%, 25% and 0% of agreement with the respective statement. This fact can be described by

Rx n є {0,0.25,0.75,1} (1)

where Rx, n stands for the respective answer to question x by occupant n.

Furthermore, we had to define an optimal answer Rx, opt for each statement. In some cases, this optimal answer would correspond to 100% of agreement (e. g. when the occupant has to rate his agreement with the statement “In general, the lighting in my office is comfortable.”). In other

cases, the optimal answer Rx, opt would correspond to 0% of agreement (e. g. when the occupant has to rate his agreement with the statement “My office often seems too bright.”). We can therefore write

Ko, є {0,1} (2) where the appropriate value for Rx, opt has to be chosen by the experimenter for each statement.

In our questionnaire, every single statement was associated with one common problem often experienced in office lighting environments (e. g. glare problems, “not enough light”-situations, missing windows, etc.). As previously mentioned, the objective of this study was to identify the weak spots of the ADS installed within the LESO-SEB. In other words, we wanted to find out which of the commonly experienced office lighting problems were the most annoying to LESO — SEB occupants. In order to quantify the specific annoyance of each of these problems within the building, we defined a mean annoyance value (MAV) for each of our statements. The MAV can be computed as follows:

n=1

where x stands for the number of the respective statement and N stands for the number of persons who have returned the questionnaire. The parameter MAV is used in the following for quantifying the extent to which a certain lighting related problem applies to the LESO-SEB. The lower the MAV, the less annoying is the corresponding problem. Another parameter used in the following is the number of occupants directly concerned by a certain problem nconcerned. A person is considered to be directly concerned when he or she has replied opposite to the optimal answer Rx, opt to a certain question (e. g. “yes” or “rather yes” when the optimal answer is “no”).

The evaluation of the questionnaires made it possible to identify the main lighting related problems that are annoying to the LESO-SEB occupants. In order to find out which weak spots within the ADS are causing these problems to them, specific complementary interviews have been conducted with some occupants.

We carried out suitability tests on microstructured plastic films for the integration into insulating glass units. As a result of our experiments UV-stabilized composite films are identified as best performing products for this application and chosen for prototyping a prismatic film with seasonal shading properties. Optical and thermal simulations conducted on a triple glazing incorporating the prototype film demonstrate the energy saving potential of this product, which provides a high solar energy gain in winter and efficiently prevents overheating in summer.

First large format glazing prototypes (ca. 850 mm x 700 mm) have already been manufactured and will now be exposed to both indoor and outdoor tests (Fig. 6). Laboratory tests will focus on the optical and thermal characterisation of the system as well as on the requisite durability of the film and the glass unit. Tests in real building aim at verifying both the theoretically predicted energy performances of the glazing and its practical reliability.

They play an important role particularly with regard to the application as transparent insulating material. Under operating conditions these components are exposed to extreme temperature and

irradiance regime, which are not Fig.6. Glazing prototypes installed on the facade of considered by standard long term test the ISFH experimental budding fOT °utdoor tests

procedures for insulating glass units.

Acknowledgment

The presented project is funded by the "Deutsche Bundesstiftung Umwelt (DBU)” with the reference number 24673. The authors gratefully acknowledge this support and carry the full responsibility for the content of this paper.

References

[1] Daniels, K., Bartenbach C. (1977), Tageslichtdurchflutung durch Sonnenschutz. Technik am Bau 3, 291-294.

[2] Critten D. L. (1988), Light enhancement using e-w aligned long prismatic arrays at high latitude. Solar Energy 41 (6), 583-591.

[3] Geuder, N., Klett, U., Fricke, F.(1998), Mikrostrukturierte Prismensysteme zur Solarenergienutzung. Tagungsbericht 11. Internationales Sonnenforum, Koln, Germany, 502-509.

[4] Hohfeld, W. et al. (2003), Application of microstructured surfaces in architectural glazings. Proceedings of Glass Processing Days, Tampere, Finland, 342-344.

[5] Christoffers, D. (1996), Seasonal shading of vertical south-facades with prismatic panes. Solar Energy 57 (5), 339-343.

[6] EN 410: 1998, Glass in building — Determination of solar and luminous characteristics of glazing.

[7] EN ISO 4892: 2001, Plastics — Methods of exposure to laboratory light sources — Part 1: General guidance.

[8] EN 1279-2: 2003, Insulating glass units — Part 2: Long term test method and requirements for moisture penetration.

[9] EN 1279-3: 2003, Insulating glass units — Part 3: Long term test method and requirements for gas leakage rate and for gas concentration tolerances.

[10] WINDOW 5.2, Lawrence Berkley National Laboratory (LBNL), San Francisco, http://windows. lbl. gov/software/window/window. html

[11] Christoffers, J., Deutschlander, T., Webs, M.(2004), Testreferenzjahre von Deutschland fur mittlere und extreme Witterungsverhaltnisse (TRY). Deutscher Wetter Dienst Verlag, Offenbach a. Main.

[12] Giovannetti F. (2006), Blendfreie saisonale Verschattung von Prismenverglasungen. 12. Symposium Innovative Lichttechnik in Gebauden, Kloster Banz, Germany, 60-65.

Claudia Vannoni[6]*, Serena Drigo1, Nicola Iannuzzo[7], Andrea Micangeli2

1 Department of Mechanics and Aeronautics — University of Rome “SAPIENZA”

Via Eudossiana, 18 — 00184 Roma (Italy)

2

CIRPS (Interuniversity Research Centre on Sustainable development) — University of Rome “SAPIENZA”

Via Tommaso Grossi 6 00184 Roma
* Corresponding Author, claudia. vannoni@uniroma1.it

Abstract

In 2001 the Italian Ministries of Environment and Justice signed an agreement addressed to the Italian jails for the installation of up to 5,000 m2 (3.5 MWth) of solar thermal collectors.

Goals of the “Solar Jails” program are the reduction of the energy consumption in jails, as buildings owned by public authorities with high and constant annual DHW demand, and the encouragement of the use of solar heat at large scale. However, besides the environmental and technical aspects addressed, the most challenging purpose of the initiative is the empowerment of the prisoners trained to install and to maintain the plant. In particular, the professional qualification gained on solar are expected afterwards to increase the reemployment opportunities.

The programme, after one pilot project in the Rebibbia jail of Rome, foresees the “solarization” of more 14 jails all over Italy by 2010. Currently two jails has been already solarized and six more are implementing the program procedures.

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.

Keywords: Public buildings, DHW plants, solar ordinances, capacity building.

For the achievement of these objectives, experts and researchers from CIRPS were called to contribute to the implementation of the educational and technical activities, in cooperation with the staff of the Italian Department of the Penitentiary Administration (DAP) and with prisoners. Personnel of the Renewable Energies Department of the Ministry of Environment and energy experts of two local cooperatives, TERRE coop. and Reseda Onlus, were also participating in the Working Group.

In 2002, a first pilot project was carried out into Rebibbia jail (Rome) where 250m2 (175 kWth) of flat plate collectors were installed with the support of 10 prisoners to produce DHW for 400 users. Started in 2006, the second phase of the program is organised in two steps. The first step foresees a second pilot initiative in Rebibbia jail aiming at developing and testing a “tool-box” for the implementation of solar projects in jails. Within the second implementation step, the action is going to be gradually extended to other 14 Italian jails located all over Italy.

The program defines the target size of 175 kWth per plant devoted to DHW production and 100% funded by both Ministries. However, jails are encouraged to contribute with additional funds for larger installations, whenever applicable.

J. Alcala1, A. Allbee[1] and A. Pereira[2]*

‘RELAB LLC, 417 Bloomfield Avenue, Montclair NJ 07042, USA

2 altPOWER, Inc, 125 Maiden Lane #308, New York City, New York 10038, USA

3 altPOWER, Inc, 125 Maiden Lane #308, New York City, New York 10038, USA

Corresponding Author, anthony@altpower. com

Abstract:

This paper will look at the vast experience altPOWER has gained over the past six years working on nine BIPV projects in Manhattan. Specifically, the division of work between the various labor unions involved in a typical BIPV project will be addressed. The BIPV mandate for Battery Park City, set in 2000 accelerated BIPV installations in NYC during the first decade of the new century. With trade unions playing an integral role in the NYC construction industry, the varying designs and cutting edge nature of BIPV has led to trade concerns and division of labor issues as projects have moved into the bidding and construction phases over the course of the last 6 years. This paper will disseminate the experiences and valuable lessons learned, adding to the knowledge base of the fledgling BIPV industry in the US and around the world.

1. Introduction

As the authors of this paper discovered during research for this document, there is little written and seemingly known with regard to the distribution of labor for BIPV systems as well as standard PV systems in mature organized labor construction markets. As Greentech media has stated, “this lack of awareness poses a hurdle for BIPV adoption especially since the vast majority of installations to date have been conventional, non-integrated systems. [1] ” Thus we found that altPOWER and RELab are in a unique position: we have designed and installed a dozen BIPV projects utilizing multiple design types (i. e. canopies, spandrel PV on cassette facades, curtain walls, louver systems and skylights) in an urban market with a complex and organized labor presence.

NYC is consistently in violation of federal air quality regulations and has one of the highest rates of infant mortality due to asthma in the world for a major city. Finally, Mayor Bloomberg’s PlaNYC focuses on sustainable infrastructure growth and has thrust the issue of clean energy generation to the forefront of policy concerns for New York City.

As a result, forward-thinking planners have embraced the use of clean technology for on-site power generation. Leading the way in this forum has been the incorporation of BIPV.

The focus of this paper is to discuss the various organized trades which will be involved with BIPV installations, how they work together and how designs and planning can make labor issues less of a concern and thus reduce barriers to the use of PV in general.

We will evaluate 5 prominent buildings in Manhattan: The Solaire, a 27 story residential tower, TriBeCa Green, a 25 story residential tower, the Helena, a 38 story residential tower located on Manhattan’s upper west side, The Verdesian, a 27 story residential tower, The Vissionaire, a 35 story residential condominium, The Millennium Tower Residences, a 35 story residential condominium, and The Riverhouse at Rockefeller Park, a 31 story 264 unit condominium tower.

Motivation for these projects comes from a greater understanding of the impact of greenhouse gas emissions (GHG) on our local and global environments as well as concerns over energy security.

Yet, perhaps the greatest encouragement has come from the political leadership in New York State which has realized that by investing in distributed generation, NYC can escape the economic and safety threats of interruptions in power supply and build on the proven reliability of its electric infrastructure. More importantly, renewable generation will help to clean NYC’s air. In particular, research has shown PV to be the most reliable power source for NYC [3]. For example, on the afternoon of July 6, 1999, the Washington Heights neighborhood of Manhattan experienced a feeder distribution circuit black out resulting in loss of life and massive economic losses. Table 1 shown below illustrates NYC’s peak demand on that day. The lower graph shows a high degree of correlation between NYC’s load and available sunshine for PV power generation on that day. Simply put, a distributed network of PV in this neighborhood may have prevented the blackout on this day.

In fact, a targeted network of PV generation may have prevented every blackout the northeast has faced in the last 5 years, including the massive August 14, 2003 blackout that placed most of the US Northeast and parts of Canada in the dark.

2.2 Incentives

Various incentives were used applied for on the above-mentioned projects. The incentives range from per watt buy-downs from grants administered by the New York State Energy Research and Development Authority (NYSERDA), to local tax credits like the NYS Green Building Tax Credit to federal incentives through the Investment Tax Credit (ITC). Perhaps most influential to these project

examples was the Battery Park City Authority’s BIPV mandate, requiring developers to install BIPV systems equal to 5% of the building’s base power load. These programs have been critical to the development of BIPV in NYC. altPOWER partnered with the development, design and construction teams at each of the host sites presented in this paper and served as the PV design and installation leader.

Jianbo. Ren1 , Yiping Wang1,2, Li. Zhu2*, Qunwu Huang

1 School of Chemical Engineering and Technology of Tianjin University, Tian Jin 300072, China
2 School of Architecture Tianjin University, Tian Jin 300072, China
Corresponding Author, zly13920679110@tiu. edu. cn

Abstract

A new radiation energy supply system for space heating and cooling was designed. Heat is conducted out from the metal tube loop buried underneath the corners through adjacent conductive glue layer to the wall and floor constructions, and then is dispersed inside mainly by radiation. The theoretical model of the system was established and the heat transfer process was simulated by the finite element analysis method. The analysis results show that the system has good cooling and heating performance. The space cooling and heating needs

in an energy-saving reconstructed building can be met with the 40°C heating medium in

winter and 10°C cooling medium in summer. This provides possibilities of more generous

requirements on the heating or cooling supply temperature. The heat flux from the floor and wall surfaces respectively contribute 60% and 40% to the total energy supplying in summer. The system performance is affected mainly by the tube diameter, fluid medium temperature. Keywords: Radiation energy supply; Heat transfer model; Thermal flux

1. Introduction

The building sector plays a significant role in the global energy consumption, especially in developed countries it accounts for 30%-50% of the whole energy consumption [1]. Use of radiant floor heat systems as an efficient way to achieve occupant thermal comfort in buildings with low — energy demands has increased.

There have been several studies dealing with floor heating systems in the literature. Weitzmann et al. [2] developed a two-dimensional dynamic model for simulating the floor heating systems. Lin et al.[3] conducted an experimental research on the thermal performance of under-floor electric heating system with latent heat thermal energy storage plate. They also prepared an analytical solution for this problem [4]. Laouadi [5] developed a model for analyzing radiant heating and cooling systems which can be used in building energy simulation software. Recently, Bozkir and Canbazoglu[6] studied unsteady thermal performance analysis of a room with serial and parallel duct radiant floor heating systems using hot airflow. Olesen [7] presented a comprehensive discussion on radiant floor heating systems and investigated on their underlying principles.

For the sake of reducing the investment, cooling supply is added into the floor radiation system to make it a dual-function energy supplier. Corina [8] said that radiant cooling system can be operated in any US climate with low risk of condensation, and can save on average 30% of the energy consumption and 27% of the peak demand compared to the traditional all-air system. Mumma [9][10] discussed the major concerns given about the radiant cooling system, such as condensation, cooling capacity and initial cost, and thus confirmed its relevant advantages.

In this paper, a new type radiation energy supply system for space heating and cooling was put forward. It was designed to meet the energy requirements by utilizing the heat conduction ability of both wall and floor by burying the metal tube in the corner. The paper constructed a two-

dimensional steady-state mathematical model of this system and studied this system by means of finite element method. Then influences of the diameter of embedded pipe, location of embedded pipe, water supply temperature on the temperature distribution and thermal flux on the floor and wall were investigated.

Figure 1 represents the DX-SAHP system studied in this work, which consists of the following components: thermodynamic solar collectors, a hermetic refrigeration compressor, a plate heat exchanger as condenser, an electronic expansion valve (EEV), a hot water storage tank with an auxiliary supplier of heat, heat exchangers inside the building and two water pumps.

A thermodynamic solar collector essentially consists of a flat aluminium plate without any glazing or back insulation and with a selective surface. It presents a centrally located tube running longitudinally where refrigerant gets evaporated thanks to heat absorbed not only from solar radiation, but also from the environment. The evaporated refrigerant is sucked in by the compressor, which drives it to the condenser in elevating its pressure and temperature. The energy rejected by the refrigerant in the condenser heats the water pumped to the storage tank. This tank

supplies hot water to heat exchangers in the building, which achieve and keep thermal comfort conditions in rooms.

The process undergone by the refrigerant can be represented by the vapour compression cycle illustrated in Figure 2. Here, 1-2 represents evaporation and superheating of the refrigerant at evaporating pressure. The isentropic compression process is represented by 2-3, however we are interested in the polytropic compression process 2-3’. After reaching condensation pressure, the refrigerant condenses until becoming subcooled liquid (point 4). Then, the refrigerant is pumped through the EEV and the throttling process takes place. At point 1, we have a two-phase fluid at evaporating temperature, which is lower than ambient air temperature.

Considering the building integrated Concentrating PV and PV/T systems, there are some operational and architectural aspects. A first notice is that in PV/T systems the cost of the thermal unit is the same either the PV module is crystalline-silicon (c-Si), poly-crystalline silicon (pc-Si) or amorphous-silicon (a-Si). Thus the ratio of the additional cost of the mounted thermal unit per PV

module area cost is different and is almost double in case of using a-Si compared to c-Si or pc-Si PV modules. The complete PV/T systems include the necessary additional components (Balance Of System, BOS, for the electricity and the BOS system for the heat) and therefore the final energy output is reduced by about 15% due to the electrical and thermal losses from one part to the other. Water hybrid PV/T systems can be used during the whole year for the pre-heating of water, since the temperature of water in the water supply network is no more than 20° C, even during summer months. Considering the installation of solar energy systems on building roof or facade, the combination of PV/T collectors with solar thermal systems have some aesthetic problems due to the different size and appearance. The problem can be overcome if there is a harmony in size and if solar thermal collectors have absorbers with same or similar color to the color of PV cells.

Based on the investigated CPV and CPVT systems some new architectural designs have been performed, giving a better idea about the aesthetic integration of them on building structure. In Fig. 7 the design of an industrial building with booster reflectors on the roof shows an example of an effective integration of them on building roof. Another design with collectors on building roof is that of Fig. 8, where CPC type solar collectors with PV/T absorber are used. The Fresnel lenses with linear absorbers are shown in the three designs of Fig. 9. The first design is the case of the sunspace (Fig. 9, left) and the other two designs demonstrate the case of atrium with the absorbers out of focus (Fig. 9, center) and on focus (Fig. 9, right), showing the effect of shading.

The design of Fig. 10 is referred to the integration of CPC reflectors on building structure. The building balconies can be used to put the reflectors, which can have the parabolic form and the reflected radiation to be focused on the back of the front building. In case of using stationary reflectors the focal line is moving up and down, depending on sun height, while in case of moving reflectors the focal line can be stable. In both cases, the sun faced building surface is lighted by the not reflected radiation and the reflected diffuse radiation illuminates the back of the front building.

3. Conclusions

Low concentration solar energy configurations have been investigated and studied regarding the effect of the concentrator type to the performance of CPV and CPVT systems. We have studied flat diffuse reflectors, which provide an almost uniform distribution of solar radiation on PV surface, linear Fresnel lenses, which achieve additionally solar control of interior spaces and CPC reflectors, which can effectively combine PV strips with flat solar thermal absorbers. The absorbing solar radiation increases cell temperature and reduces electrical efficiency, but several modes for efficient and cost effective heat extraction can be applied and the most appropriate, according to the application requirements, can be selected. These new concentrating collectors can be integrated on buildings being adapted with their architecture and contributing to the energy and the aesthetic requirements of it.

Acknowledgements

The contribution of the architect Maria Tripanagnostopoulou to the designs of the paper is warmly acknowledged

References

[1] Gordon J. M., J. F. Kreider and P. Reeves, Solar Energy, Vol. 47, 245-252, (1991)

[2] Klotz F. H., Noviello G. and Sarno 13th European PV Conf. 23 — 27 Oct., Nice, Paris, 372 — 375, (1995)

[3] Fraidenraich N. Progress in Photovoltaics: Research and Applications, Vol. 6,. 43 — 54 (1998)

[4] Poulek V., M. Libra, 16th European Photovoltaic Solar Energy Conference, 1-5 May, Glasgow, UK,

2453-2546, (2000)

[5] Goetzberger A., Proc. 20th IEEE Photovoltaic Specialists Conference, Las Vegas, 1333 — 1337 (1988)

[6] Zanesco I. and E. Lorenzo, Progress in Photovoltaics: Research and Applications, 10, 361 — 376, (2002)

[7] Mohedano R., P. Benitez and J. C. Minano, 2nd World Conference and Exhibition on Photovoltaic Solar

Energy Conversion 6-10 July, Vienna, Austria, 2241 — 2244, (1998)

[8] Garg H. P. and R. S. Adhikari, Int. J. Energy Res. 23, 1295-1304 (1999)

[9] Brogren M., M. Ronnelid, B. Karlsson, Proc. 16th Europ. PV Solar Energy Conf., 1-5 May, Glasgow,

U. K. Vol. III, 2121-2124 (2000)

[10] Nilsson J., R. Leutz and B. Karlsson, 19th European Photovoltaic Solar Energy Conference, 7-11 June,

Paris, France, 2094-2097, (2004)

[11] Edmonds I. R., I. R. Cowling and H. M. Chan, Solar Energy 39, 113 — 122 (1987)

[12] Yoshioka K., S. Goma, S. Hayakawa and T. Saitoh, Progress in Photovoltaics: Research and

Applications, Vol. 5, 139 — 145, (1997)

[13] Zacharopoulos A., P. C. Eames, D. McLarnon and B. Norton, Solar Energy, 68, 439 — 452, (2000)

[14] Nabelek B., Maly M. and Jirka VlRenewable Energy, 1, 403-408 (1991)

[15] Kaminar N., J. McEntee, P. Stark and D. Curchod. 22nd IEEE Photovoltaic Specialists Conference, Las

Vegas, 529 — 532, (1991)

[16] Jirka V., Kuceravy V., Maly M., Pokorny J. and Rehor E. WREC V Part III, 1595-1598. (1998)

[17] Wheldon A., R. Bentley, G. Whitfield, T. Tweddell and C. Weatherby, PV systems. 16th European

Photovoltaic Solar Energy Conference, 1-5 May, Glasgow, UK, 2622-2625, (2000)

[18] Whitfield G. R. and Bentley R. W. 2nd World Conf. On photovoltaic solar energy conversion, Vienna,

Austria, 2181-2184, (1998)

[19] Verlinden P. J. Terao A., Daroczi S., Crane R. A., Mulligan W. P., Cudzinovic M. J. and Swanson R. M.

Proc. 16th European PV Conference, Glasgow, U. K., 1-5 May, 2367-2370, (2000)

[20] Tripanagnostopoulos Y., Nousia Th., Souliotis M. and Yianoulis P. Solar Energy, 72, 217-234, (2002)

[21] Y. Tripanagnostopoulos, M. Souliotis, S. Tselepis, V. Dimitriou, Th. Makris. In CD Proc. 20th European

PV Solar Energy Conf. Barcelona 6-10 June (2005)

[22] Y. Tripanagnostopoulos, Ch. Siabekou and J. K. Tonui. Solar Energy, 81, 661-675 (2007)

[23] Y. Tripanagnostopoulos, M. Souliotis, R. Battisti and A. Corrado. Progress in Photovoltaics-Research

and Applications 13, 235-250 (2005)

[24] Y. Tripanagnostopoulos. Presented in 21st European PV Conf. Dresden, Germany 4-6 Sep (2006)

[25] Y. Tripanagnostopoulos and A. Iliopoulou. Int Conf. 22nd PVSEC, Milan, Italy, 3-7 Sep. (2007)

The passive house PH+ concept is applied to a series of typical office building geometries and possibilities for on-site renewable energy production to reach zero net energy buildings are explored with the following assumptions:

• PV installation on the roof and facades (with total efficiency of 11%)

• Solar thermal system installation on roof and/or south facing facade (total efficiency of 56%)

• Roof cover 90%, facade cover 40%

The results of the parametric study are summarized in Figure 4. Here, energy consumption figures are shown in MWh/a in order to be able to balance the energy with on-site generation. It can be seen that only four building geometries provide enough floor and facade area to produce enough energy to balance the energy demand of the design. It can further be seen that energy concept PH requires only a small amount of heating energy but a large amount of electrical energy. The energy concept with reduced internal gains (PH+) reduces overall energy consumption but increases the amount of heating energy demand. This is still beneficial for zero net energy buildings since PV and solar thermal systems can be applied to the building envelope. Depending on the building form there is enough roof and faqade area to generate renewable energy necessary fulfilling the ZNE definition. In Figure 4 building forms and energy concepts with ZNE (without red and white columns) are buildings with 2 floors (1a and 1b) and 3 floors (2a and 2b). All other building forms do not provide enough building envelope to fulfil ZNE definition. Here, other energy concepts might be applicable in order to reach ZNE.

3. Conclusion

Newly introduced building regulations aim to reduce energy consumption in buildings. In heating dominated climates like Norway this implies more stringent building envelope requirements to reduce heat losses. Insulation and air tightness of the building envelope ensures this but can as a result lead to overheating problems during the summer period. Consequently, especially in buildings with high internal loads like commercial buildings, cooling equipment may be needed that uses additional energy. This will have consequences for the design of energy efficient buildings in Norway in the near future. Bioclimatic design strategies which focus on avoiding active cooling might be applied more regularly. Especially architects and engineers have to be

aware of the consequences of design decisions in regard to building form and envelope. It is proposed that thermal comfort criteria should be developed and coupled to energy calculations. Especially thermal comfort in (a hotter) summer will be reduced and should be put in focus when designing buildings and energy concepts.

The results show that the air tightness of the building envelope and the efficiency of the heat recovery system are the most sensitive parameters (together with the outdoor climate). Therefore, the energy concepts focused on those two parameters. With appropriate energy concepts applied to different building geometries it could be shown that ZNE office buildings are possible. There are some difficulties in implementing the passive house standard to office buildings due to differences in internal heat loads and occupation hours, resulting in differences in heating and cooling demand. Consequently, internal heat loads were reduced (PH+) and this resulted in more building shapes that allow for ZNE.

Another challenge is that climate change predictions for Norway forecast an increase in mean temperature and precipitation [8]. This has the potential to increase the overheating problems in future summer periods and might even extend it to autumn and spring seasons. Especially in western parts of Norway this may also lead to hot and humid summer periods. Further work is needed in order to quantify the extent of energy related implications. Also cost implications have to be studied in order to be able to optimize the design options.

References

[1] I. Andresen, 0. Aschehoug, Bell, M. Thyholt, Energy-Efficient Intelligent Facades. A state-of-the-Art, in: SINTEF (Ed.), SINTEF Building and Infrastructure, Trondheim, 2005.

[2] K. A. Dokka, T. H. Dokka, User Guide SCIAQ version 2.0, SCIAQ Pro — Simulation of Climate and IndoorAir Quality, 2004.

[3] T. H. Dokka, I. Andresen, Passive Houses in cold Norwegian climate, 10th International passive house conference, 2006.

[4] T. H. Dokka, Hermstad, Energieffektive boliger for fremtiden — En handbok for planlegging av passivhus og lavenergiboliger, SINTEF Byggforsk, SINTEF Byggforsk, Trondheim, 2006.

[5] Enova, Bygningsnettverkets energistatistikk 2006, enovas bygningsnettverket, enova, Trondheim, 2007.

[6] M. Haase, I. Andresen, Energy-efficient office buildings in Norway — from low energy standard to passive house standard, Passivhus Norden, Trondheim, Norway, 2008.

[7] M. Haase, I. Andresen, Key issues in energy-efficient building envelopes of Norwegian office buildings, in: C. Rode (Ed.), 8th Nordic Symposium on Building Physics, Copenhagen, Denmark, 2008.

[8] K. R. Lise, A. G., S. Eriksen, K. H. Alfsen, Preparing for climate change impacts in Norway’s built environment, Building Research & Information 31 (3-4) (2003) 200-209.

[9] K. J. Lomas, H. Eppel, Sensitivity Analysis Techniques for Building Thermal Simulation Programs, Energy and Buildings 19 (1) (1992) 21 — 44.

[10] PHI, PHPP 2004: Passive House Planning Package 2004, in: T. P.H. Institute (Ed.), The Passive House Institute, Darmstadt, 2004.

[11] I. Sartori, A. G. Hestnes, Energy use in the life cycle of conventional and low-energy buildings: A review article, Energy and Buildings 39 (3) (2007) 249-257.

[12] TEK, Energi — Temaveiledning, in: StatensBygningstekniskeEtat (Ed.), Vol. TEK 2007, Norsk Byggtjenestes Forlag, 2007.

[13] P. Torcellini, S. Pless, M. Deru, D. Crawley, Zero Energy Buildings: A Critical Look at the Definition, National Renewable Energy Labratory, 2006.

[14] K. Voss, G. Loehnert, S. Herkel, A. Wagner, M. Wambsganss, Buerogebaeude mit Zukunft, Solarpraxis, Karlsruhe, 2006.

[15] T. Wigenstad, T. H. Dokka, T. Pettersen, l. Myhre, Energimerking av nsringsbygg, SINTEF Building and Infrastructure, Trondheim, 2005.

The Solar Building XXI has in the south fagade 96m2 of PV (Polycrystalline), which correspond to 12kWp, plus a 6kWp (Amorphous silicon) in the car parking in front of the building (see figure 12). These two systems are responsible for an overall PV annual production of 12 MWh (in the fagade) plus a 8MWh (in the car parking), which correspond to around 76% of the electricity consumption of the building.

2. Acknowledgement

To INETI and Program PRIME by the financial support to this Project. To Arch. Pedro Cabrito and Isabel Diniz authors of the Architecture Project and all colleagues which participate in the Project Alves Pereira; Manuel Nogueira, Antonio Joyce and also to all the workers which make it possible.

References

[1] Helder Gongalves, Pedro Cabrito, Passive and Low Architecture Conference Proceedings, Vol. 1 (2006) 821­825.

A simulation model was a detached house. The plan and elevation views are shown in Fig. 6, the building material specifications in Fig.7, and the schedules of various items in Fig.8. The areas for the analysis were Sapporo(43°4’N, 141°21’E), a cold weather region, Tokyo(35°39’N, 139°41’E) and Osaka(34°41’N, 135°30’E), mild weather regions, and Naha(26°12’N, 127°41’E), a hot weather region. The Standard year of expanded AMeDAS weather data 1981-2000 for each area were used.

Natural room temperature and thermal load when the roof is assumed to be autonomous perspiration (autonomous perspiration mode) were compared with those of non-perspiration mode in summer (Sapporo: from July to August, Tokyo and Osaka: June — September, Naha: May — October). The specific sense temperature of the autonomous perspiration mode was set to five kinds (20, 25, 30, 35 and 40 °С). The air-conditioning case (living & dining room, master room and children room are air — conditioned) shown in Fig.8 and un-air-conditioning case (all rooms un-air-conditioned, i. e., natural room temperature calculation case) were both investigated, and in the former case, the room set temperature and humidity were 27°C, 60% during the cooling period. The areal supply water temperature, changed monthly, was assumed to be equal to the monthly average outdoor air temperature in each area.