Without strong government incentives, BPIV is only viable in big projects with large budgets
This week Footprint attended the annual building integrated PV (BIPV) conference, held at the RIBA. Organised by the BRE and billed ‘an essential guide for designers’, the conference aimed to get architects and suppliers together to give designers a clearer understanding of how PVs can be integrated into buildings.
The speakers included Lee Polisano of PLP Architecture, Alastair Guthrie of Arup, Robert Studd from HOK, Pascal Mittermaier of Lend Lease, and Steve Pester from BRE. Their presentations were accompanied by talks from various manufacturers and suppliers of BIPV, including Sunways AG, Ertex Solar, Romag, and Polysolar.
BIPV has historically been expensive, but in the past two years the costs of silicon has fallen by 50 per cent, and this is being reflected in the costs of PV systems. The choice of whether to install BIPV often lies between the upfront investment costs and the operating costs.
BIPV is about using the PV as the building material, rather than as an add on. It involves substituting standard building materials, such as cladding or glazing, in order to allow the PV to form an integrated part of the building façade.
The factors that influence BIPV include:
- Site suitability
- Building use
- Client preferences
- Costs constraints
- The functionality required from the PV
In recent years many different types of BIPV have come onto the market, and developments are constantly being made.
The main types of BIPV include:
- In roof mountings with standard PV modules
- Tiles, slates and shingles
- Roofing membranes
- Glass – glass laminate transparent components
- Double glazed PV modules
- Laser etched transparent PV
- Opaque PV
Many of the speakers stressed the need for the use of PV to be integrated right from the start of any project. Kevin Webster of manufacturer Romag said: ‘there is more to BIPV than just putting a few panels together – the design of panels and building requirements need to be considered from the start’. Many of the manufacturers speaking at the event called for architects to involve them from the start of projects, in order to develop the most appropriate products together.
The conference kicked off with a talk from Lee Polisano of PLP Architecture. Lee spoke of the challenges in developing the Heron Tower, one of the first tall buildings to integrate PV into its façade in London.
The development was led by the belief that the building and operating of towers can consume a disproportionate amount of resources. The practice wanted to combat this preconception with the design of the tower and create a precedent for future development in the city.
Using PV on the roof of the tower would not have provided enough area, so they made the decision to look at the building’s façade. It is worth noting that the BIPV on the Heron Tower only provides 3.5 per cent of the buildings total energy consumption.
Lee said that the greatest obstacles to greater use of BIPV are government policies, observing that they ‘do not incentivise innovative technology’. He believes that for sustainable building technologies, like BIPV, to become more widely used, they need to be ‘made more widely useable in buildings even when the economics don’t necessarily stack up’.
Alastair Guthrie of Arup, called for BIPV to be used only when economically sensible, when it reduces lifetime carbon emissions and when it enhances the elegance of the building. He added that a hierarchical approach to efficiency should be adopted. Reducing the energy demand of buildings should be carefully considered before PV is even approached. Designers should only use PV once the building form, envelope and systems had been addressed.
With BIPV still in its infancy, the industry needs to consider the recyclability and reuse of their products when they reach the end of their usable life. Many of the manufacturers at the conference neglected to answer this question, waving it off with remarks such as ‘the PV will last for the lifetime of the building’.
Aimed at designers, it was interesting to see that only seven practices were represented on the conference’s delegate list of ninety - raising the question of whether the industry is really connecting with architectural practice. With BIPV still mainly being used on large projects with big budgets, such as HOK’s Frances Crick Institute, it remains unlikely that it will become a commonly specified building product in the near term.