Workshop: brainstorming ideas for a residential high-rise
Being in the business of design requires architects to have a highly developed spatial awareness, and this ability is particularly important when it comes to creating cost-effective residential high-rises. The objectives of this workshop are (i) to discuss requirements specific to cost-effective high-rise accommodation (such as optimised central services cores and economical floor plans for apartments), (ii) to design new and independent solutions, and (iii) to implement the municipal spatial planning programme sustainably and with a minimum of resources.
1 – Growing cities and the drive for greater urban density
Cities are attractive and appealing places and are set to remain so in the future – people are flooding into urban areas right across the world. Our society is simultaneously in flux, affecting family structures, employment opportunities, leisure and mobility habits and the way we work, share space, live and communicate, to name but a few examples; cities are growing faster than any other kind of locality and can thus react most effectively to these changes. While this growth is fundamentally positive, the process inevitably throws up considerable challenges “on the ground”.
Chief among these is the challenge of packing more people and structures into less space (inward rather than outward growth, as it were) – an issue with which almost every expanding city in Europe is wrestling. This kind of growth strategy makes sense not least for reasons of sustainability, as inner city areas generally enjoy good public transport connections. It is also critically important for any city that wishes to continue flourishing in the future to have a balanced social mix, and this encompasses the entire demographic spectrum – young and old, rich and poor, locals and foreigners alike; the mix in any area should ideally be a microcosm of the population as a whole. By the same token, our cities cannot continue to grow more concentrated and compact, i.e. accommodate a never-ending stream of new inhabitants, without providing additional open spaces and public infrastructure. The process of increasing urban density sustainably is one of architecture’s biggest challenges, but it is also a great opportunity for urban construction and architecture in particular – new urban development solutions and typologies are required.
2 – Building upwards
Building upwards is one effective way of increasing urban density, although it is no secret that constructing high-rise buildings is very costly: stricter fire prevention standards, an emergency services lift, emergency stairwells and wind bracing, not to mention earthquake protection, all have their price. This presents us with a dilemma: while high-rise buildings offer an effective solution to the urban density challenge, the economic realities associated with their construction seem to run counter to the goals of creating affordable living space and cultivating a healthy social mix.
3 – Affordable accommodation
Reasonably priced housing makes a significant contribution to the way a city works and to its quality of life. Vienna serves as a good example in this respect. It has topped the rankings as the world’s most liveable city for years. With approximately 65% of its stock classified as “social” – and thus affordable – housing, a diverse population can live and work in the city at a reasonable cost. At the other end of the spectrum sits London: as accommodation costs across the entire city are no longer affordable for lower – or indeed middle – incomes, the costs of day-to-day living and working in the city are also spiralling into the stratosphere. The most recent public opinion polls in Zurich, the city with the world’s second-highest quality of life, show that almost half of all citizens consider housing to be the most pressing political issue, with the focus squarely on the search for affordable accommodation.
4 – Living in high-rise accommodation
Over the last few years, high-rise accommodation has returned as both a subject for discussion and an option for the building industry. The construction costs for a high-rise residential building are typically at least 10-15% higher than for a conventional dwelling block, however, and this means that if high-rise residential accommodation is to play any part in affordable housing, new and innovative solutions centred on floor plans, construction and prefabrication must be sought. The trend towards smaller, more compact floor plans – as well as towards more single-occupant households in two- and three-room homes – highlights the complex challenges involved in plotting residential high-rises.
Every high-rise building has a significant presence in the cityscape and must thus offer clear added value for society. This value may reside in its location within the city, in public access to the ground or top floor, or indeed in the creation of publicly accessible open spaces. High-rise residential accommodation also features specific conditions that are a function of its type: for example, living on the ground floor and on the lower floors tends to be unpopular. The below-ground rooms with which we are familiar generally make little sense as this basement space has to be used for building services or parking. Careful consideration must also be given to the question of outside space for each accommodation unit because of potentially extreme wind conditions. The structural engineering should also be carefully checked to ensure that the residents on the top floors are not exposed to unpleasant building motion during high winds. And, as already mentioned, particular attention must be paid to fire prevention measures: each storey will require appropriate fire escapes that reflect its floor plan layout. Similarly, every high-rise building must also be equipped with emergency service lifts and the materials used must meet enhanced fire prevention standards.
5 – Optimised, space-saving floor plans
Inextricably linked with the drive for greater urban density is the question of economics – an issue of both current and future urgency that encompasses not only narrow, commercial considerations but also the wider meaning of the term. Given the increasing shortage – and thus cost – of land reserves in cities, our homes must be as space-saving as possible. Equally, housing is strongly influenced by the specific uses to which it is put – people cook in the kitchen, the bathroom is for hygiene, you sleep in the bedroom and spend leisure time in the living room (probably the only room in which we see some latitude in terms of usage options). In addition, residential construction investors tend to have conservative notions of housing use, favouring only what is familiar and firmly established. This is compounded by an ever more labyrinthine maze of regulations: noise emission limits, disabled-access stipulations and fire prevention regulations – to name but a few – shape and constrain the floor plans of our homes.
6 – Access and outside space
A key prerequisite for a holistically planned and economically conceived floor plan is a central services core in public use, with a pressure-ventilated emergency stairwell, an emergency services lift and a residents’ elevator. These three elements form a unit and are accessed via a public space, so an efficient and compact layout is essential. A central services core made from concrete will simultaneously serve to brace the building and the corridors leading to the accommodation unit entrances can be accessed via this core, which is protected by fire doors.
Outside space is a great asset to any accommodation, and a balcony creates a link between outdoors and the interior of a building, satisfying the residents’ need for fresh air, sun and exposure to the natural world. This outside space must be very carefully planned, however, particularly in a high-rise building, as nature can make itself felt in the form of high winds – and a sense of personal safety can also come into play above a certain height. Inset loggias (or “seasonal rooms”) may represent an interesting solution here and can enhance the appeal of a home.
C The task
Against this backdrop, it is clear that cost-effective, high-rise living can play a decisive role as a tried-and-tested method of dealing with current demographic growth in flourishing and attractive cities; it does so by addressing such expansion quantitatively, sustainably and economically.
The task to be addressed in this workshop: working in groups of two, design a high-rise residential block with a maximum height of 60 metres.
The priority here is to provide efficient access for six to ten apartments per floor. This building core will consist of a pressure-ventilated emergency stairwell, an emergency services lift and a residents’ elevator, and will also contribute the necessary bracing for the high-rise structure. The apartments are to be arranged around the core with a view to creating a simple building shape.
Affordable living space is in short supply in most of the world’s cities today. Residential high-rises will be able to support the social and political drive for affordable housing only if they can be built efficiently and cost-effectively; space-saving apartment floor plans are thus highly topical.
A diversified accommodation profile would involve small housing units, i.e. one-room studios and one-bedroom flats, complemented by two-bed and a few three-bed units.
The following conservative apartment sizes should be taken as guidelines:
1-room unit: 31m2
1½ -room unit: 39 m2
2-room unit: 46 m2
2½-room unit: 53 m2
3-room unit: 69 m2
4-room unit: 85 m2
The surface area of the individual floors should not exceed 600m2.
The floor plan layout of each apartment, how it relates to the outside space (balcony), and how the height affects the use of the apartments, will of course also be of interest.
We are looking for an economic high-rise residential block that can be built quickly using repetitive prefabrication. Care should be taken that both the structural elements and the requisite installation shafts can be run through the entire building easily, but – above all – in a straight line.
Particular attention should be paid to the ground floor and its use: a generously proportioned entrance zone should form the reception area and street focus of the building. No accommodation units are to be laid out on the ground floor as this space is reserved for communal areas or public use.