Innovative BIPV rooftops: development, realization, and monitoring of 2 BIPV field tests in the Netherlands

Building Integrated PV (BIPV) is seen as strategy to realize the EU target of Nearly Zero Energy Buildings (NZEB’s), while at the same time creating an aesthetically acceptable built environment. This in contrast with Building Added PV (BAPV) of which the result is often seen as aesthetically unwelcome additions to new and existing building. BIPV might have some negative aspects considering lifespan and PV output besides the aesthetical positive effect. In this research project two field tests are realized to investigate the negative aspects of different BIPV solutions, focusing on the effect of back-string cooling of PV modules on PV electricity output, relative humidity and lifespan. These aspects are seen as possible bottlenecks for large-scale acceptance of BIPV in society and the design, realization and monitoring of these field tests can contribute to an increased implementation of BIPV through improved BIPV solutions

Comparative performance assessment of four BIPV roof solutions in the Netherlands

A significant amount of global energy consumption takes place in the built environment, with as collateral effect CO2-related climate change. One of the strategies to realize a significant CO2 reduction is by integrating photovoltaic modules in the building envelope (BIPV). Disadvantages of BIPV include a possibly lower energy output and a possibly decreased life span due to the lack of optimal cooling of the PV modules. Currently, cooling of PV modules is usually realized by passive back-string ventilation, which is under strain when integration PV modules in the building envelope. In this study, a comparative field study of BIPV is conducted in the field lab ‘The District of Tomorrow’ to generate insight into BIPV efficiency as a function of back-string ventilation. This paper presents a selection of the monitoring results of the realized system, consisting of 24 PV modules in 4 segments with a total of 6000 Wp output with different amounts of back-string ventilation. The measurements indicate that in a moderate climate BIPV solutions without back-string ventilation result in increased operating temperatures, lower electricity output and condensation between PV modules and rooftop surface. To decrease relative humidity levels and operating temperatures to acceptable values, back-string ventilation is seen as an effective cooling medium in the presented field case

Sol-gel coatings on large area glass sheets for electrochromic devices

The preparation of vanadium and tungsten oxide coatings is described using vanadium oxide tri-2-propoxide/2-propanol and tungsten penta-ethoxide/2-propanol solutions. These solutions are dip coated onto K-glass substrates and cured. For vanadium oxide coatings it is shown that sol-gel/dip coat processing is a feasible production technology for very homogeneous vanadium oxide coatings on large area sheets with good electrochromic properties. Homogeneous vanadium/titanium oxide coatings with a titanium contents up to 40% and charge capacities up to 45 mC/cm2 are obtained. Homogeneous tungsten oxide coatings with reasonable electrochromic properties (coloration efficiency up to 34 cm2/C and transmission changes up to 5:1) are prepared

Preparation and characterization of thin zeolite MFI membranes on porous supports

Thin (2–7 μm) polycrystalline randomly-oriented zeolite MFI membranes were prepared on an -Al2O3 support by one or more subsequent hydrothermal treatments. Different particle sizes (275–700 nm) in the layer were achieved by changing the synthesis temperature (371–459 K). Zeolite membranes, prepared by two subsequent hydrothermal treatments have an optimum quality. Membranes prepared by a single hydrothermal treatment have defects and zeolite membranes obtained by three or more hydrothermal treatments become too thick and crack during the removal of the template. The zeolite MFI membranes were characterised by permeation measurements using single gases and mixtures of n-butane (n-C4H10) and iso-butane (i-C4H10). Permselectivities, F, and separation factors, , for n-C4H10/i-C4H10 decrease strongly with an increasing number of defects and hence provide a good indication of membrane quality. The separation, on the other hand, of a CH4/n-C4H10 mixture at high occupation of n-C4H10 is not much affected by small defects. This is ascribed to blocking of those defects by capillary condensation of the butane. Flux values decrease linearly with increasing zeolite crystallite size in the top layer indicating that the effective membrane thickness is only one particle thick. During hydrothermal treatment zeolite particles also grow at the other side of the support but do not decrease significantly the flux through the supported zeolite membrane

Exergetic building envelope

In this research project the interaction between embodied, consumption and generation of energy, embodied land and exergy in the building envelope will be investigated. The objective is to create an interactive model that gives insight in the impact of different functions and their interaction, which will be tested in a demonstrator

Making the assessment right, or making the right assessment?

While its design has significant impact on the sustainability of a building, assessment methods to measure sustainability in design phases are not widely used. If assessment methods are applied, it is debateable whether they can generate the insight that is needed to realize a truly sustainable built environment. In this paper the assessment of two important aspects in relation to building sustainability, energy and materials, is investigated. The paper consists of a comparison of these aspects with regard to different assessment strategies. Finally, an alternative indicator offering another perspective on assessing sustainability in relation to architecture is introduced