Back to the future: A re-examination of high-rise
Published 24 March 2015
How can we achieve sustainable design practices for high-rise residential to ensure contemporary schemes don’t succumb to the same fate as the developments of the 60s and 70s?
High-rise residential developments built during the 60s and 70s in the post-war period have had an enduring negative legacy on the perception of high-density and high-rise residential living. Whilst these developments were laudable for their social aspirations in their central aim to create socially sustainable and aspirational living spaces, the legacy that has endured is largely a negative one.
In order to ensure that contemporary and future high-rise residential developments do not succumb to similar fates, intelligent approaches to their development and life cycle are vital. In the UK there isn’t a strong legacy, or tradition of high-rise residential living. The development of UK specific standards that learn from the world's best examples, that understand the failures of the past and that are mindful of the unique nature of UK society, would lay firmer foundations for sustainable future high-rise developments in this country.
Outside of the building itself the unique character of UK cities requires a sensitive approach to the ways that high-rise residential is incorporated into the built fabric. The podium developments of the 60s and 70s are largely incongruous with the historic urban fabric of UK cities, and their development often further fragmented the urban fabric. Avoiding the isolated podium towers of the 60s and 70s is paramount to creating a more human interaction with the buildings. The notion of human scale should also be extended to the design of the street frontages of the buildings.
A key failure of the 60s and 70s was the imagined society that would inhabit these futuristic and utopian architectures did not necessarily reflect the realities of society. Their isolationist and brutal forms did not suit the people who were to live there. Overcoming the often socially isolating structure of high-rise residential developments requires an understanding of the spatial arrangement of the components of the building, from the living spaces, through to the spaces that connect them together and social spaces that are incorporated into the building. Understanding how these function together and can be designed so they do so harmoniously and adaptably will require significant effort, but has the potential to ensure that they are sustainable as social spaces as well as living spaces. The integration of multiple uses, such as commercial and retail, that are not simply tacked on but planned in conjunction with the residential spaces, could create important social dynamics that sustain the buildings’ vitality in important ways.
The adaptability of buildings is also of paramount concern when thinking about life cycles and enduring relevance. Aiming to design buildings with potential for the uses and spaces to be adapted over time as the local human, economic and wider social demands of the built environment change, can contribute to the fundamental sustainability of high-rise residential into the future.
What innovations can we apply to achieve quality buildings, living spaces and public realms?
Re-appraising what quality actually means may be necessary to achieve affordable builds that deliver desired levels of space and facilities. In order to minimise costs more functional approaches to aesthetics may be required. This could permit larger residential units or enhanced facilities in the buildings for the residents. In other words: amenity.
At alinea, we were involved in a study in 2013 for Lipton Rogers that looked at how the nirvana of a highly efficient, cost-effective yet liveable housing product might be achieved. Among other things it used an industrial approach to the design and construction of the shell: maximising pre-fabrication techniques, simplifying details to de-risk the whole process and provide the basis for a potential roll-out of thousands of units. It is putting into use on a live project, where different architects for respective plots are working to a brief of a common chassis, but are able to add their touches by exploring particular facades or introducing refinements that respond to site-specific issues.
The interaction between the building and the public space surrounding it is one area of quality that receives relatively little attention. However the interfaces between building and their surroundings inform the experience of the building for both the inhabitants and the public, which will inform opinions about high-rise residential developments.
Amenity space can be conceived as running through the building at multiple scales, from balconies, to hallways, to communal spaces and outside into the space around the building. Acknowledging the relationships between these spaces and how they can work together as a whole continuum will allow the quality of the amenity spaces to be enhanced by thinking of them collectively and planning them in a joined up way. In the shared amenity spaces a sense of ownership and participation are useful in fostering a sense of ownership of the spaces. This can be brought about through residents being in charge of certain aspects of the amenity space management and maintenance, and allowing flexibility in their uses so residents can define the kind of amenity that they are looking for. Through creating the sense of ownership and collective participation in the building more active engagement with other residents could be brought about. This in itself will contribute to an important aspect of quality that if is often neglected in residential building development, namely social amenity and participation.
What are the different types of tenure models (and how applicable are they to tall buildings)?
To understand whether certain tenure types are suited to high-rise living, we must first look at the differences in design metrics as well as the variations in cost and value of each.
There are four types that fall under the same set of rules: market sale, private rental sector (PRS), shared ownership and Affordable. Space standards are not governed by policy but are considered during the planning decisions as a way of upholding suitable living standards. Within Greater London the London Housing Design Guide (LHDG) incorporates Lifetime Home standards as well as minimum space requirements to improve upon new housing developments in the capital. Whilst these are not statutory requirements, these standards have been adopted by all London boroughs and included in planning policies and (barring exceptional circumstances) are adhered to. We are also seeing these standards being used outside of London.
Houses of Multiple Occupancy (HMOs) have space standards which are set out by the Housing Executive and the size of the bedrooms is driven by the number of occupants in the dwelling. Not only are they tighter in terms of required space when compared to other tenure types, the composition of the space is more akin to student accommodation and hotel layouts with shares amenities commonplace.
Therefore, when the space requirements of all tenure types are considered, there appear to be no barriers to high-rise construction.
When we look at the implications that each tenure type has on the cost of construction, and the shell in particular, it is important to understand what drives the need to build high. The cost of high-rise is generally higher than the low/midrise equivalent and the reasons for such a build are:
- High cost of land: By maximising density of the site, one can offset the cost of site acquisition;
- Available site footprint: Constrained sites are common in urban areas so high-rise development could be the only option to deliver the required numbers;
- Maximise views: To help drive desirability and increase sales values;
- Prestige and presence: As above but also to make an architectural statement.
To deliver high-rise residential development that is commercially viable, developers require a much stricter set of design parameters than the equivalent low rise scheme. A strong appreciation of how metrics such as net:gross, wall:floor, floor plate geometry and vertical transportation affect construction cost is required to deliver a viable residential product to the market.
The private or market sale tenure is therefore most suited to high-rise development as its viability appraisals tend to have suitable allowances to accommodate the design deliverable of high-rise residential. Whereas with social housing (including affordable and shared ownership), developers returns are diminished when compared to market sale, so it is rare to see high-rise developments.
When planning stipulates that a percentage of a high-rise development must be given over to social housing, the developer has the following options:
- Incorporate into the design, generally looking to place social units in the lower levels of the tower where sales values are lower for the market units;
- Provide for the delivery of social housing elsewhere in the borough.
The application of high-rise to HMOs is very much dependent upon the specific category of housing. Bedsits, shared houses and lodgings tend to be management of existing housing stock due to the low rental return and type of fit-out. They would therefore not be considered when high-rise development is required.
The high-rise typology has been used for hotels and student accommodation developments in Greater London with success. Small room sizes (approximately 6.5sqm to 20sqm) allied to high rental values achievable in the London market with a high overseas student population fulfils the commercial appraisal. Although, to make the appraisal truly viable, the design must be lean in respect of façade are and palette of materials.
In a similar vein, PRS has also started to be incorporated into high-rise developments in London. Investors who have traditionally looked at the commercial office rental market and the yields that this achieves are beginning to look at PRS as it has a similar return profile. PRS developments to date have tended to be located in areas where market sale residential would be classified as ‘sub-prime’, ranging from £500-£800psf sales. The reason being that land values in these areas are low enough to support the viability appraisal.
At this level, the cost of a PRS development is generally higher than its market sale equivalent due to the provision of amenity areas and durability of internal specification items (kitchen worktops for example). Given the timescales for gross profit return on rental properties, it is important to minimise the input construction costs in order to minimise lending or finance required. Therefore, to make PRS work in high-rise projects, serious consideration must be given to façades, net:gross and the potential for prefabrication/standardisation.
- Market Sale tenure can readily accommodate delivery of high-rise living in the vast majority of Greater London boroughs. This will also apply in most regional urban areas where sales values can support the tall building economics.
- Social Housing (RSL and Intermediate) tenure models in most cases do not work in high-rise residential appraisals. Even when developments require a % of social housing, where tall buildings are concerned, authorities would rather have the commuted sum and deliver a greater number of cheaper low rise units elsewhere in their borough.
- HMO and in particular student and hotel tenures can be made to work within tall building envelopes. They can achieve this through having a strong pipeline of repetitive work enabling prefabrication, standardisation of fit out items (bathroom pods etc) and simplifying floor plates and façade materials. This is generally confined to London where the availability and cost of land require tall building massing to gain required units and rental values are high enough to support viability.
- The PRS model can and has been used within residential high-rise development. Taking aside the issue of gaining institutional investment the key challenge for the PRS market in delivering high-rise development is standardisation akin to the student/hotel tenure model. Prefabrication and simplification of the external envelope will help the PRS high-rise model become a viable option in areas of sub prime residential areas. Its inclusion outside of London in all but major urban areas is considered impractical as the construction costs will be too high to justify when land and sales values are diminished.
What technologies could be utilised to enhance high-rise living?
Technological advancements are often the catalyst of great industrial change, the invention of the I-Beam for example was integral to the creation of the first modern high rise buildings in New York and Chicago. Current challenges to high-rise living such as construction cost, design standards, personal expectations and future operational issues will inevitably be solved by further advancement. But what are these solutions? And what enablers need to be in place for them to proliferate?
The cost of construction is often cited as one of the primary reasons for high-rise living being limited to the top-end of the property ladder. In the UK the residential towers are predominantly focused on London and its metropolitan boroughs. With typical sales values of between £600/sq.ft and £3,000/sq.ft+, even at the lower end of the scale a typical one bed, could at least £300,000, which for most is too much. With land aside, construction has become one of the biggest components to this cost. With time, risk and often non-standard construction details being cited as the main drivers alternatives that could be explored are:
- Modular frame construction: The use of standard sized pods or units would enable faster and greater economies of scale;
- Standardised cladding systems: The total wall area to cover can mean that the total cost of construction is heightened within tower developments. Using a base chassis system across a range of projects would again drive house builder economics and reduce costs.
All of these require developer, builder and most importantly government buy-in to really move forward. The last recession led to the loss of a number of big players in the modular supply chain. Further investments and incentives for SME’s is required to bring around the next set of modular suppliers.
A futurist view is one where, within certain design limits, whole floors or apartments could be modularised and connected to existing building frames.
Within the initial investment, there is also the considerations given to the adaptability of spaces; especially when the space is limited. Apartment joinery and wall construction is picking up on the lessons of the Bauhaus movement of the 1950s where modular and wardrobes can be manipulated so that the space changes. One example if this the Heron development in central London where the typical apartment sizes are smaller than the usual market, but are termed as City Crash pads where the key joinery rotates, fold and flips to turn wardrobes into beds and open plan into bedroom and living room. This might require a paradigm shift in living expectations but examples from Hong Kong and Singapore have shown that over time this might become a more common trend.
Max-packing and dense development places a great strain on existing infrastructure. Self-sustaining habitats will be crucial to future success. Some towers have hitherto attempted to draw this in to their design but to arguably limited effect. The following are some examples of possible systems:
- District heating & Centralised Energy Centres: Centralised boilers and heating systems that can generate enough hot water and heating for more than one development. This has started to become more prolific within London development but requires up front investment that may take years to realise its full potential.
- Renewable energies on site: The wind energy generated by eddying on wind over towers, integrating solar panels into facades and recycling water. Unfortunately these need to be placed in a way that maximises their potential for energy generation without blighting living standards and design.
- Use of Smart systems: In response to the new creation of new utility infrastructure are also the progression of technologies that can reduce user demand. Currently the majority of installations in new developments provide the user with readers that can tell the user how much energy they are using. Further development will likely be equipped with integrated systems that respond to user requirements and behaviours, automatically switching off during down patches and seeking system efficiencies when demand is greater.
Beyond these generally available technologies, there will some future development that is a game-changer for the way housing (and tall buildings) is designed, delivered and occupied. The step change may emanate from 3D printing or from material advances (perhaps even nano technology), or some other innovation. Its arrival may help to solve the housing crisis that is with us in London and brewing elsewhere, but certain principles will not change: the need to create sufficient quantities of decent quality homes at affordable prices and in a way that uses land and infrastructure efficiently.
Steve Watts, alinea consulting LLP/CTBUH Trustee and UK Country Lead
Ashley Dhanani, University College London
Alex Hyams, alinea consulting LLP
Mike Coplowe, alinea consulting LLP
Rachel Coleman, alinea consulting LLP
Robert White, CTBUH