In a first step we compared an interior Venetian blind measurement using a large integrating sphere [Platzer, 19XX] with the solar transmittance calculated with the two radiosity models. The measurement of the exterior blinds shown in Figure 1 was deemed to be to complicated as the port aperture of the sphere is close to one period of the shading device. For the interior blinds with smaller period several measurements with laterally displaced blinds were averaged.

Figure 4: Comparison of optical measurements for Venetian blinds (25mm white) for different tilt angles are compared to modeled data using WIS and the ISE model.

From the comparison of experiment with model data one can conclude that both methods reproduce quite well the optical transmittance in the main parts of the angular incidence intervall. As predicted WIS overestimates direct maximum transmittance to some extent — that would be even more extreme with dark slats (one has to take into account that due to the 10 degree calculation intervall the maximum value of 100% is not sampled in most cases).

The ISE extended view factor model gives a better approximation for the maximum transmittance, however, for large negative incidence angles (reflections from the ground) this model seems to underpredict the transmittance.

In order to see the effects for the more complex lamella shapes of Figure 1, we have to have a look at the calorimetric measurements.

Total solar energy transmittance through external blinds

Three variants of this blinds have been measured in combination with a glazing coated on position 2, namely white, white-perforated and brown lamellas. For this lamella geometry the differences between the two models are more pronounced. In the maximum transmittance region, but very similar in others (see Figure 5 and Figure 6). The differences are in line with the ones observed with the integrating sphere measurements, however modulated to some extent by the glazing behind the blinds.

For internal blinds the glazing should have an even more important influence on the angular function. This can be seen in the next paragraph.

Total solar energy transmittance through internal blinds

0.70

0.60

0.

Internal Venetian white blinds have been tested and modeled with two different solar control glazings. Both comparisons with experimental data show a very good correspondence of the results. The small differences between the models are due to different treatment of the glazing data. The angular dependence of a float glass pane was used for the the glazing g-value in the simplified ISE model. This is obviously not completely consistent with the measured data, especially for the glazing Ipasol 6634 in Figure 7. However, this has no big influence on the overall result.

Internal roller blinds

Table 1: Modeled and experimental g — and U-values for glazings with internal grey roller

shading	inc. angle	Ventilation [l/min*m]	g [-]	U2 g [W/(m2K)] [-]	U [W/(m2K)]
Ipasol	0	0	0.219	0.86
	0	60	0.229	1.37
	0	24	0.221	1.06 0.218	1.06
	60	24	0.19	1.06 0.184	1.06
Silverstar	0	0	0.284	0.94
	0	60	0.297	1.46
	0	30	0.291	1.20 0.305	1.21
	60	30	0.245	0.258	1.21

8The specific cost of the whole solar-field investment with allocation of the overhead expense would be 139 €/m2 at a size of 300 000 m2

[1] Including Biomass boiler

[2] Starting point were 150 €/m2 (solar field size 437’639 m2) for a »third« plant. Using the cost structure of the Solarmundo collector the specific investment resulted in 130 €/m2 due to systematic collector optimization (e. g. more mirrors for one absorber tube). The formula leads so reduced specific costs for large units.

[3] Currently the raising of this tariff is being discussed in Spain.

[4] In previous examinations it was found out that a more sophisticated power cycle does not lead to lower LEC due to 1.) higher specific costs, 2.) elevated heat losses in the solar field and 3.) higher suiting losses due to the fourth collector section for intermediate superheating.

[5] Other operating strategies are conceivable as well.

[6]The aperture width is defined as the net primary mirror-field Wap = N x B

[7]levelized electricity cost

[8]The sunshape is assumed to be a distribution with a circumsolar-ratio of CSR=7.5%

[9] If one considers not the local distribution but the effective distribution over a sufficient absorber length

[10]The effective relative radiance Xeff is referred to the incident beam radiation Ib

[11]It is calculated with the optimal configuration for an optical error of a — = 4.56 mrad

[12] Wagon moved above the appropriate cover, PEM deactivated and lowered, then acti­vated again to retrieve the cover by lifting it up;

[13] assessment of error at each intermediate stage of calibration and processing, a final error being deduced;

[14] profilo climatico dell’Italia, ENEA, 1999

[15] “Manual de Arquitectura Bioclimatica”, Guillermo Gonzalo, Tucuman 1998

[16] The solar system has been design together with Antonio Bee from Costruzioni Solari s. r.l.

[17] The air solar system Solarwall has been design together with Rolando Malaguti from Solarwall Italia

[18] Binz, A. (Projektleitung): MINERGIE und Passivhaus: Zwei Gebaudestandards im Vergleich, Schlussbericht. Ausgearbeitet durch Zentrum fur Energie und Nachhaltigkeit im Bauwesen, im Auftrag des Bundesamtes fur Energie (BFE), Marz 2002. (Vertrieb: EMPA ZEN, CH-8600 Dubendorf, www. empa. ch/ren )

[19] Kleiven, T. (2003) Natural Ventilation in Buildings. Architectural concepts, consequences and possibilities. PhD thesis at Department of Architectural Design, History and Technology, NTNU.

[20] Lapithis, P. Solar Architecture in Cyprus. PhD theses, University of Wales, UK, 2002

[21] Ibid

[22] Ibid

[23] Ibid

[24] Kolokotroni, M., The Thermal Performance of Housing in Greece: a Study of the Environmental response to Climate, MSc, Bartlett School of Architecture, UCL, 1985.

[25] Ibid

[26] Sergides, D. “Zero Energy for The Cyprus House", The Architectural Association, 1991

Solar Heating and Cooling Implementing Agreement

Energy Conservation in Building and Community Systems Implementing Agreement

12 P. Nitz et al, "Sonnenschutz und Lichtlenkung durch mikrostrukturierte Oberflachen",

Tagungsband 9. Sympos. Innovative Lichttechnik in Gebauden, Staffelstein, 23./24.1.2003, S. 103-108

[30] C. Buhler „Mikrostrukturen zur Steuerung von Tageslichtstrbmen“ PhD thesis, A.-L.-Universitat Freiburg, Germany (2003)

[31] V. Wittwer, A. Georg, W. Graf, J. Ell, Casochromic Windows, ISES Solar World Congress 2003, Gbteborg, Juni 2003

[32] T. J. Richardson, J. L. Slack, R. D. Armitage, R. Kostecki, B. Farangis, M. D. Rubin, Switchable mirrors based on Nickel-Magnesium Films, Applied Physics letters 78 no. 20 (2001) 3047-3049

[33] DDC „direct digital control”

[34] PCU: „processor controlled unit“

[35] PT100: Platinum resistor temperature sensor, 0°C, 100,000 i increases each above 1 °C approx.. 0,4 i

[36] up to now, there is no signal from this

[37] D/A-converter: converts analogue (electrical) in digital bits.

‘Data allocated by BASF. Shear-velocity from 50 to 450 і

10.5

20 30 40 50 60 70 80

Epitaxial Layer Thickness (mic.)

[40] V. Perraki, Thesis (Paris 1988).

Figure 4. Efficiency graph versus of base thickness (pm) for polycrystalline Si solar cell under AM 1.5 irradiance conditions, calculated for grain size 250 pm and variable

[42]gb.