General information Location: Solar Office Doxford International, United Kingdom Sunshine hours (yearly average): 230 hours Type of project: Educational Type of application: BIPV Time for design process: 6 months, overlapping with construction Time for construction: 12 months Realization: 1998 [ Top ] Description The Solar Office is a new office building designed for Akeler Developments Ltd on the 32ha Doxford International Business Park, located near Sunderland in the north east of England. It is occupied by a leading e-commerce company: www.domainnames.com. The brief for the building and its procurement follow the robust fast-track pattern that is now commonplace in speculative office development. The Solar Office is the first speculatively constructed office building to incorporate BIPV and the resulting solar façade is the largest so far constructed in Europe. It is one of the few BIPV projects to adopt a holistic energy strategy. The brief required the design of a speculative office building that fully meets the requirements of the commercial market. It also required the building to be designed to ‘best practice’ low energy, environmentally sound principles. The client supported initiatives taken by the architect to include a worthwhile PV installation, but would only agree to include it in the brief if it was wholly funded from outside sources and it did not extend the design and construction program. Accordingly the 4 600 m² three storey building was constructed to a ‘shell and core’ specification. It is fitted out to suit the specific requirements of the occupying tenant. The tenant was encouraged to operate the building in its low energy 'passive solar' mode, but chose to augment this strategy by utilising the provision made for comfort cooling due to high project incidental cooling loads. It can, if necessary, be divided into up to six separate tenancies. The whole building was designed and constructed over fifteen months on a design-and-build basis. This means that the contractor was required to construct it within a fixed cost, to a fixed delivery date with the consultants novated to the contractor on completion of an approved outline design. The overriding objective in terms of the environmental design was to find a synthesis between the low energy measures and those needed for an effective photovoltaic installation. [ Top ] System characteristics PV system power: 73 kW utility-interactive Type of building integration: building façade Type of cell technology: Mono-crystalline square cells Module dimensions: 70 Wp – 285 Wp (350) polycrystalline silicon, Manufacturer: Kyocera Inverters: Central inverters 35 kW (2) [ Top ] Project cost breakdown The cost of delivering the shell-and-core building was made up as follows: Building construction: GBP 3 514 000 (€ 5 658 600) Landscape and infrastructure: GBP 365 000 (€ 587 800) Professional fees and other charges: GBP 346 000 (€ 557 100) Total: GBP 4 225 000 (€ 6 803 500) The costs of the fit-out was as follows: Fit-out: GBP 600 000 (€ 966 200) Professional fees and other charges: GBP 54 000 (€ 87 000) Total: GBP 654 000 (€ 1 053 200) [€ 1 = GBP 0,621] [ Top ] Performance characteristics Over the first two years the PV array has generated some 113 000 kWh/year, which compares well to the design prediction. Most parameters - irradiation, ambient temperature, input and output power - were recorded as average values over 10 minutes. Data was downloaded from an on-site computer on a weekly basis and analyzed by Newcastle Photovoltaics Applications Centre. A total output of 94 790 kWh was recorded between March 1998 and May 2000. Some inverter problems experienced during the summer months masked the seasonal differences in performance that were expected, although there was a noticeable improvement in efficiency during the winter months. Efficiencies for the four PV subsystems have also been calculated. These consist of two large arrays connected to 3-phase inverters, and two small arrays connected to single-phase inverters. The smaller subsystems exhibited consistently lower performance than the larger systems. Half the difference was assigned to the fact that the smaller subsystem array has a higher proportion of lower efficiency modules due to higher cell spacing. The remainder was assigned to a lower efficiency of DC/AC conversion. It is usual to derate inverters for climates where there is a significant percentage of operation under low light conditions . In this way the loss of output under occasional high insolation conditions is more than offset by the increased efficiency at low insolation conditions. In the Solar Office, the large inverters are rated at 98% of the corresponding pv array capacity, while the small inverters are rated at 90% of their corresponding pv capacity. Assuming similar low level light, the small inverters should give slightly higher subsystem efficiencies. However, the single-phase inverters have exhibited slightly different performances. This is partly due to different solar input thresholds and partly due to transparency differences between the modules. While the major difference between the two inverter sizes is due to low light-level performance, this had had very little effect on total performance as the subsystems with the small inverters represent a small proportion (2,6%) of the array capacity. Electricity generated: 113 000 kWh from April 1998 to March 2000 System availability: 100 % for second year of operation Incidents or Outages: several shut-downs of one inverter from June 1998 to October 1998 [ Top ] Project team Client: Akeler Developments Ltd 7 Clifford Street, London W1S 2WE Tel.: +44 (0)20 7864 1800 Fax: +44 (0)20 7864 1801 Project architects: Studio E Architects Ltd Palace Wharf, Rainville Road, London W6 9HN Tel.: +44 (0)20 7385 7126 Fax.: +44 (0)20 7381 4995 PV Design: Studio E Architects + Rybka Battle Structural Engineers: Whitby and Bird Partnership Ltd Building services: Rybka Battle Contractor: Bowmer and Kirkland PV manufacture: Kyocera [ Top ]