|5 Hanover Square|
As part of Green Sky Thinking Week I attended a seminar and building tour at the recently completed 5 Hanover Square in central London. Designed by Squire and Partners, the site is located within Mayfair's conservation area with listed buildings surrounding it. This in itself was a restriction. To add to that the client (Mitsui Fudosan) drove the sustainability agenda for this building demanding 10% renewables.
Completed in 2012, the £26m mixed use development achieved BREEAM excellent for the office building and Code for Sustainable Homes Level 4 for the adjoining apartments. It looks like any other office building except it throws in as much sustainability into a building as it can given the site constraints:
- photovoltaics on the roof - these are angled at the optimum 30 degrees and are cleverly located to conceal the roof plant. They are also installed on the mansard roof.
- living wall - this is installed on the north-east (back) facade of the building and is fed by rainwater that is harvested and filtered
- post tensioned concrete slabs - these reduced the amount of concrete used since the slabs could be thinner and required less reinforcement
- 40% of the cement content of the concrete was replaced by GGBS (ground granulated blast-furnace slag), a by-product of the iron ore industry
- 25% of the aggregate content for the concrete was replaced with stent, which is a by-product of the China Clay industry
- 97% of waste was reused or recycled
- LEDs used throughout the building
|mansard photovoltaic roof|
|photovoltaics on the roof|
From the above list it's clear to see that there has been a lot of thought put into the reduction of energy use for maintenance of the building but also the embodied energy of the materials used. Simply looking at the concrete content alone we can see the significant carbon reduction by the use of waste products. This makes me think that concrete could be less of an evil than first imagined, if the correct 'ingredients' are used.
Apart from the material carbon savings, there are perhaps more renewables that could have been employed on site. However, the location of the building is very restrictive. Wind turbines were considered as an early solution but testing on site proved to be less successful and therefore photovoltaics were chosen. The site's proximity to the Crossrail tunnels also prevented any technologies such as ground source heat pumps which could have otherwise been incorporated.
This building is one of the few sustainable office buildings I have visited and in appearance it looks much like any other office building. This could be a good or a bad thing, depending on your personal opinions. I have the view that if a building can look like a 'normal' building yet out-perform and in a more intelligent way, then all the better. But then I also believe that the building should portray its 'green-ness'. It's a shame that the living wall is on the back facade hidden from sight. I would have preferred for it to be a prominent feature of the building and it's disappointing that it's not. Perhaps this was a restriction of the conservation area...
The office floors are bright allowing good views out to the city and also letting in plenty of natural light. The flats latched onto the end of each floor are somewhat disappointing as spaces. Although thought has been put into the specification, the stair treads are already chipping and the spaces are small and dark. I don't think it would be my choice of a place in the city.
Despite my minor criticisms above, this project should be judged on its merits. It's a building that is working hard to be sustainable and so far it seems to be doing well. I guess the real test will come once the building is fully occupied and operational and whether it still performs as it's designed to.