Tower blocks, the bête noire of the 1980s, are now going through something of a renaissance in London notably, at least those offering commanding views of the cityscape, not all of it socially uncontroversial, as demanding city clients push for high spec upgrades. At the same time, many local authority and private residential blocks now require refurbishment.
As the upper end high rise and other flats have come onto the market, for example in Kensington and Chelsea, the rest of the high rise real estate, much of it still in local authority ownership, is experiencing rather more problems in financing maintenance, let alone upgrade.
Upgrading sustainability and particularly energy performance of flats and maisonettes* is a key challenge nationally, as they dominate many city centres. In March 2006, they accounted for 16% of total UK accommodation, according to DCLG figures for 2006/7**, of which 12% were purpose-built and 4% conversions. There are over 3,000 high rise residential blocks alone in the UK, with disproportionate levels of economic hardship.
However, the national figure is heavily skewed by London, with well above the national average proportion of flat accommodation, at 44%, with 31% purpose-built and 13% conversions.
As a consequence, high rise refurbishment has been an important priority for the Mayor of London, in several cases combined with wider regeneration and district heating projects which lend themselves relatively well to high density developments.
Towering achievement?
One of the largest and best-known projects has been the £10m, 22-storey Glastonbury House refurbishment in Pimlico, London, completed in April 2007. The project, which features as a key case study in the DTI-funded Sustainable Tower Blocks Initiative, was carried out on behalf of Westminster City Council/CityWest Homes, with Cole Thompson Anders as architects, and main contractor Wates Construction.
In January 2001, Westminster City Council commissioned action research network INTEGER, of which CTA is a founder member, “to investigate options for the intelligent and green refurbishment of housing in general, and specifically residential tower blocks”.
A key aspect of the refurbishment was that, unlike in other schemes, the elderly and vulnerable residents as sitting tenants were not obliged to evacuate before work could begin, each flat being vacated in turn for less than a month.
In addition to wider social priorities, including open space, common areas and security measures, the environmental remit focused on sustainability, low energy, water and waste.
On energy, the brief was to “target 50% savings and a 50% reduction in carbon emissions through more efficient heating and lighting systems, improved building insulation and use of renewable energies such as solar water heaters, photovoltaics and wind turbines”. Cavity wall insulation was fitted throughout, and a 4m high, 6kW wind turbine is intended to provide energy for residents, together with 17.92m2 of building-integrated Louvres-type 2.24kWp Sharp 80w panel solar PV system provided by Solar Century, the latter expected to generate 1,600kWh per year, saving some 908Kg CO2 per year.
Water management measures aimed to save 40% “through efficiency measures including rainwater harvesting, use of spray taps and grey water recycling”, together with flow restrictors on toilets. A sedum roof has also been integrated. Construction waste reduction was tackled by “closer management and off-site fabrication”, with pre-contract specifications for re-cycling, and considering use of waste separation, compaction and other technologies.
Architecturally the most impressive feature is the conversion of the old boiler room into a sky lounge, with spectacular views across central London. The project has generated considerable expertise in reduced cost refurbishment of tower blocks, working rapidly around tenants, on the outside of the building as far as possible, use of building-integrated renewables. Other challenges included asbestos removal, costly rewiring with avoidance of damage to walls, and integration into local district heating.
Consequently, the building has achieved a “Very Good” EcoHomes rating, challenging for a large block of this sort, though unfortunately lack of baseline and detailed subsequent energy performance data backing this up are not available. Another major refurbishment scheme in Sandwell, West Midlands involved two 9-storey 1962 tower blocks housing elderly tenants, again as part of a wider regeneration scheme. The blocks were both popular, with good community cohesion, but lacking renovation for almost 40 years, with poor maintenance, and anti-social behaviour, making them difficult to let. Key problems included poor thermal insulation of external walls, metal-framed single glazed windows, underperforming underfloor electrical heating, encouraging high energy use, condensation and draft.
Some 950 units have been demolished on the estate, replaced by 650 new-build, with 200 of these homes as social housing. There were questions over limited participation of residents in refurbishment decisions by owners Sandwell Metropolitan Borough Council, including in demolitions, but the results are nevertheless impressive.
The tower work involved costly refurbishment to a high specification not easily justified on cost grounds alone, but as a flagship project for the town, and to demonstrate best practice to neighbouring private developments. A comparable 8/9 storey block in the area cost £1.2m for mainly basic bathroom and kitchen upgrades to reach Decent Home Standards, while greater ambitions for Bowater House raised this to £1.8m. Fortunately Sandwell’s location in a Regeneration Area released Single Regeneration Budget funding for renovation works, with additional funding from MBC Capital, Advantage West Midlands, CEC (European funding), DTI, and the Energy Savings Trust, overseen by a well-organised Council team. However, costs were raised by temporary re-housing need and liquidation of the developer.
Key sustainability features added included photovoltaic panels for Bowater House and solar hot water panels for Braybrook House, recycling of grey water, improved daylighting through increased window sizes, with aluminium overcladding of buildings and low-e glazed windows raising external wall u-value to above 0.45W/m2. Acoustic insulation was added, with low energy lighting on timer and illuminer switches in the common spaces and corridors. Trickle vents and mechanical ventilation with heat exchangers were also fitted in every flat.
Gas boilers replaced the under floor heating system, heating and hot water supplemented in Braybrook by solar collectors. Heat exchangers cost around £1,000 per flat. The result has been a 60% cut in residents` energy bills with greater comfort reported.
Problems include some noise issues from ventilation systems, occasional discomfort from summer heat, solid waste chutes without a separation or recycling strategy, and smell issues affecting grey water recycling to showers and baths in a third of the flats leading to its discontinuation. Also, rents can not realistically be increased, and the cost of the photovoltaic cells rule out a viable payback period.
Mixed scheme
In a recently approved £80m refurbishment project involving the run-down 1970s Crossways Estate in Bow, London Borough of Tower Hamlets, PRP Architect’s, acting for SWAN Housing Association, proposed a masterplan with “new housing for rent and sale and the full refurbishment of the existing towers”. The original concept, with three 25-storey towers and high-level walkways, deteriorated physically and socially, due to neglect and vulnerability to crime. As with the Glastonbury House project, it was considered that the only effective approach would be to consider sustainable refurbishment and upgrade, in this case including a range of new build elements including timber frame, within a wider sustainable communities approach to regeneration, reducing crime and raising overall environmental quality.
The phased project will be completed by 2011, and “includes new housing for rent and sale, substantial new infrastructure and the full refurbishment of the existing towers”, says PRP. It points out that the existing towers “will be fully re-clad and re-fitted internally to provide high quality, low energy homes”, and that “the refurbishment is planned to create an important local landmark and symbol of regeneration, with rooftop lighting effects visible throughout the Borough”.
High performance windows and new insulation will raise thermal performance of all flats.
Lessons learned
Key challenges for sustainable refurbishment of high rise buildings and other blocks of flats, such as unfavourable VAT rating, restrictions on energy efficiency grants, failure to apply stamp duty relief to flats, and technical risks including presence of asbestos were explored in SB13, pp.14-16.
The case studies here reveal other more practical challenges, such as the need for viable community participation, better funding of maintenance and monitoring, the need for strong project management to deal with multiple funding sources and careful phasing of works, complex patterns of ownership, particularly in private blocks, discouraging innovation.
Consequently, sustainable refurbishment of high rise buildings tends to be less attractive to developers than new build, being seen as a larger risk, except where gentrification is likely, while all too often freeholders, head lessees and their agents have little incentive to upgrade sustainability performance.
Where refurbishment of tower blocks by more forward-looking local authorities occurs it is often seen as part of a wider regeneration process in the area, with new build typically a major feature.
At the same time, tighter Building Regulations relating to refurbishment in Part L, and to new build, which will have long term implications for refurbishment, requirements of the Energy Performance in Building Directive, including Energy Performance Certificates, Display Energy Certificates, HIPs, BREEAM EcohomesXB, and growing consumer pressure all point to gradual market transformation in both public and private complexes of flats.
Refurbishment within large-scale clusters of regeneration projects also provide major opportunities for development of CHP and district heating schemes.
A useful overview with case studies and indicative costs, including further detail on some covered here, is available online as The Design Guide, created by consultants Price Myers, Battle McCarthy, Franklin Andrews, Architype architects, and STBI, with DTI support, at: www.sustainingtowers.org.
*eg, Energy Efficiency Best Practice in Housing. Energy efficient refurbishment of existing housing – case studies: Good Practice Case Study 418, EST; **2006/07 Survey of English Housing, Defra
u www.communities.gov.uk/documents/housing/xls/table-117; u www.integerproject.co.uk/westminster.html, u www.colethompson.co.uk; u www.architype.co.uk; u www.prparchitects.co.uk; u www.pricemyers.com/sustainability