Description
For the environment, only the overall ecology or energy balance is relevant. Accordingly, every planning task must aim to minimise its overall environmental impact. Although a variety of highly sophisticated instruments are available for assessing the environmental impact of a building, these can only be applied once the building has been planned in its entirety. During the design process itself and the conceptual development of complex buildings, such as housing or homes for the elderly, one must instead follow basic principles, which, once the design has been drawn up, can be evaluated and optimised using simulation programmes.
The following section examines how fundamental principles and hierarchical criteria can be employed for the design of residential buildings for the elderly. Special attention is given to “energy consumption” as a key indicator of environmental impact. To determine an ecologically relevant energy balance, the architecture must be considered in its totality: over the entire life cycle of planning and construction, the building’s use and operation, and recycling.
A | Planning and construction
The basis of every ecological measure is the planning of the building itself. It is at this stage that environmental pollution and energy consumption can be reduced most at comparatively low cost. This applies to an even greater degree to regional and urban planning. Large-scale regional and urban planning measures, which for example are responsible for regulating transport and the routing of utilities, have a fundamentally greater effect than individual measures at the level of a building. For the elderly, this means that they should be able to live nearby so that they are able to take part in public life. This not only helps prevent the isolation of older, less mobile people but also reduces traffic (and the associated environmental pollution). In this respect, the integration of old people in their traditional environment and their close proximity to friends and relatives can be regarded as an “ecological measure” in itself.
For the building itself, increasingly effective energy-saving measures in the construction of a building (“embodied energy”) have resulted in a proportional increase in the relevance of the energy expended for the day-to-day running of buildings. Careful planning offers great potential for implementing effective ecological measures without great expense. A key factor for the ecological balance of the construction is the quality and environmental friendliness of the building materials used as well as their performance in relation to their environmental impact (a particular level of performance, such as structural stability, fire protection or thermal insulation is assessed in relation to its environmental impact and the embodied energy of the respective material). Different models are available for evaluating the ecological quality of materials.
In addition to selecting appropriate building materials, it is also necessary to consider transport and the organisation of the construction. Here too, this should not solely be considered and decided from a technical point of view but be regarded as an aspect of the planning process and design. For example, soil that does not necessarily need to be excavated will not require transportation or result in environmental pollution; lighter materials with more manageable dimensions are easier to transport to the site. As roughly 90% of construction transport requirements result from excavated mass and the building carcass, this is where optimisation will be most effective. Similarly, as almost all environmental pollution resulting from the transportation of building materials is caused by heavy goods vehicles, rail-bound means of transport (trains and trams) represent an attractive alternative that should be considered wherever feasible.
Well-organised building site practices can – when exploited – improve the overall architectural quality, for example when the finished building serves as a “testimony” to its construction and reminds one of its own history. For the construction, building materials should be easy to detach and separate from each other, i.e. through mechanical rather than adhesive fixture. Building elements should be easy to reach and replace where necessary – the “longevity” of a building contributes significantly to its ecological balance – and where possible should consist of recycled or “replenishable” materials (building materials made with renewable resources). Many replenishable building materials are also healthy from a building biology perspective and therefore well-suited for old people.
B | The use and operation of a building
Heating energy consumption is the first area where energy-saving measures should be applied as here the largest and most cost-effective savings are to be made. The energy reforms in recent years have therefore rightly focussed on reducing heating energy requirement. For the elderly, this is all the more relevant as older people generally feel comfortable at higher room temperatures during the heating season. In addition, older and less mobile people spend more time at home than younger people.
In a traditionally insulated house, a temperature rise of 1˚C corresponds to a 6% increase in heating energy consumption. Housing for the elderly should therefore be better insulated than standard housing. Note that although in absolute terms, energy consumption in highly-insulated houses increases more slowly with indoor temperature than in poorly-insulated houses, its proportion as a percentage of overall energy consumption rises more quickly.
One can improve the indoor climate of a building by adding energy from outside and/or through its structure and construction. The more sustainable solution is through construction measures aimed at minimising heat loss through the external skin of the building and/or recovering heat loss with the help of technical installations.
Retaining warmth
Building measures aimed at retaining warmth include:
Reducing the external surfaces through which heat is lost, by improving the surface area to volume ratio (less surface area, or a greater volume for the same surface area, equates to less heat loss per heated cubic metre), improving the building’s geometry and reducing the external temperature through the addition of buffer spaces (unheated extensions) or by partially burying the building (in winter the ground is warmer than the air).
Improved thermal insulation:
• Opaque building elements (walls and ceilings): A layer of thermal insulation of at least 20 cm (for example cork) for external walls and 30 cm for roofs represents an economically viable level of insulation. From an ecological perspective, even thicker layers would be advantageous but significantly reduce the amount of useable floor space where the building itself cannot be made larger. Vacuum insulation materials are more effective, offering a similar level of insulation at around a tenth of the material thickness compared to conventional insulation materials. At present these materials are, however, very expensive and are not easy to correctly install in practice.
• Layers of insulation are generally placed on the external surface of the construction (improved indoor climate, upkeep of the construction). Highly-efficient insulation reduces the level of energy consumption and also provides a more comfortable indoor climate as our subjective sense of well-being indoors is dictated largely by the temperature difference between the surface temperature of walls and the air temperature. Where room temperatures are higher, such as where old people live, this temperature difference becomes particularly important.
• Transparent building elements (windows): Today many improved products are available, such as triple-glazing with dense gas fillings or reflective coatings as well as associated products such as laminated glass inserts and thermally-efficient frames. Because transparent elements generally insulate less well and highly-insulated glass is expensive, it is important to take into account their colder surface temperature, particularly where old people are concerned. A sufficient level of indoor comfort – where the temperature difference between window and air is as low as possible and circulating air does not cool excessively on the inner surface of windows – can be achieved by selecting windows with a “passive house” specification (Uw < 0.85 W/m² K).
• Construction details: As the thermal efficiency of the aforementioned opaque and transparent materials improves, heat loss through poorly executed details becomes proportionally greater. Likewise, poor detailing can more rapidly lead to building defects.
• Airtight building envelope: The loss of (warm) air from the building is closely related to the construction details. The greater the indoor to outdoor temperature difference, the stronger the pressure of air movement from indoors to outdoors. Should warm air penetrate the construction and condense, it can lead to serious building defects. Housing for the elderly should therefore fulfil the airtightness requirements of passive energy standards (measured using a blower door test which creates a 50-pascal pressure difference between indoors and outdoors; the air change rate under these conditions should not exceed 0.6 per hour).
• Minimisation of ventilation heat loss: As inhabitants require constant fresh air (approx. 30 m² per person per hour) there is a limit to the amount of heat loss one can prevent via the building’s envelope. However, warmth contained in ventilation and flue gases can, to a large extent, be recovered before it leaves the building by passing it through a heat exchanger. Although older people are less active and may therefore require less fresh air, homes for the elderly are often more densely populated. As a result, the need to recover the warmth in the air is more important than it is for general housing. A mechanically-controlled ventilation system fed through a heat exchanger also ensures optimal fresh air quality, which is important for people more susceptible to illnesses; it also efficiently removes odours.
Building measures aimed at retaining warmth (“passive energy house standards”) can be an economically viable means of reducing the energy demand to a level of 40 to 50 kWh/m² per annum in regions with a Central European climate. Internal heat sources can provide around a third of the energy demand; the remainder must be covered through other means.
Heat gain
Typically, the largest directly available source of renewable energy is the sun. The sun can be used in architecture in a variety of ways:
Passive solar gain:
The sun has a stimulating, healing and enlivening effect on people and is correspondingly important for old people as well as the frail. Passive solar gain, which admits as much solar energy into a building as possible, is therefore a doubly valuable way of providing warmth in housing for the elderly. In winter, however, the sun shines only part of the time and irregularly, making it difficult to predict the effect of passive solar gain. Because it is influenced by a large number of different factors (level of insulation, room temperature prior to solar irradiation, level of comfort as temperature changes, regulation mechanisms for parallel heating systems, heat flow in the building, user behaviour, thermal absorption capacity of the building construction, furnishings and so on) it is highly complex to calculate and requires computer simulation tools. As a result, planners have often adopted other systems that are easier to manage and predict, and the benefits of sunlight for the residents of low energy buildings have been exploited only rarely. The low popularity of this form of solar gain represents a missed opportunity for elderly residents in regions of Europe that are not particularly sunny.
Home for the Elderly, St. Pölten; conservatories as sun verandas
Home for the Elderly, St. Pölten; a glazed roof allows sunlight to flood the atrium
Home for the Elderly, St. Pölten; a conservatory or winter garden provides an ideal way of enjoying the winter sun
A simpler alternative to direct passive solar gain (heat retention directly in the living space) is an “isolated” form of passive solar gain using a winter garden or conservatory. Here greater temperature fluctuations can be tolerated, making it possible to increase the amount of glazing and – despite its comparatively low efficiency in absolute terms – to absorb considerable passive solar energy. The heat gained must first, however, be transferred to the rest of the building, which is most simply achieved by incorporating the winter garden directly in the building’s automatic ventilation system. Conservatories also provide an ideal means for elderly people as well as the infirm to enjoy direct sunlight. Here they can experience the healing power of the sun; an old man who was hard of hearing once told me enthusiastically that he could hear better after a few hours in the sun in the conservatory.
The principle of passive solar gain
Computer simulations have shown that conservatories which are attached to the building’s ventilation system provide a heating contribution of around 20 %.
Further variants of exploiting passive solar energy include translucent thermal insulation or similar absorptive thermal insulation systems. These kinds of insulation allow sunlight to penetrate into the structure of the insulation, warming either air that is trapped in miniature cavities so that it cannot circulate causing it to act as an insulator, or the material itself. A further kind of solar collectors are windows containing adjustable metal lamella in the cavities between the panes that absorb solar energy and warm the air between the panes to a relatively high degree so that it can be transferred to a thermal mass.
Passive solar energy can be used to cover a further third or half of the heat demand of a building. This leaves only a small remaining amount of heat demand – that cannot economically be reduced any further by ecological means – which can also be covered using energy from the sun (approx. 5-15 kWh/m²a).
Active solar heating:
The term active solar heating was initially used to denote all systems that required some form of technical installation. Today many “passive” solar strategies also employ automatic control and ventilation systems (hybrid systems) and the term active solar heating now refers predominantly to solar water heaters. In addition, there are also solar air heaters, though these are comparatively uncommon.
Active solar water heaters are elements that although technically independent should generally be integrated into the building for better performance. The collectors are mounted on the south-facing surfaces of the building, which means that elderly residents cannot benefit from direct sunlight in these areas. Their advantage is that the water in the collectors has good thermal retention properties and is able to store the heat of the sun and provide warmth when the sun does not shine (passive solar gain is by contrast only usable for the duration of each day). The heat generated by the solar water heaters can be used effectively in low-temperature heating systems. Such heating systems require large heat-emitting surfaces and provide primarily radiant heat. This form of heating is known to be physiologically beneficial for older people.
The principle of active solar heating
Given the low altitude of the sun in winter, its weaker strength and lower abundance, relatively large collector surfaces and large thermal reservoirs are required to be able to cover the heating requirement (simulations are necessary to calculate its efficiency) and the collectors should be arranged at a steeper incline rather than a low angle (in winter vertically-arranged solar water heaters offer similar performance to 45˚ inclined collectors, while avoiding overheating in summer). Future technology will further improve the efficiency of these collectors, for example by making better use of lower temperatures using heat exchangers or through the generation of electricity from excess heat using a Stirling engine.
Indirect use of solar gain:
This refers to the use of warmth from the sun stored in the ground or in water: air inlet pipes in the ground or water tubing laid underneath a building serve as earth-air or earth-water heat exchangers. Heat pumps are also effective means of recovering energy from the heat stored in ground water or in deeper underground strata (geothermal energy).
External energy sources:
These should only be used to cover any “residual heat demand”. Here too, ecologically-friendly alternatives that make use of renewable energy sources (such as biomass) are preferable to methods that negatively impact the environment (for example large hydroelectric power stations). Non-renewable energy sources should not be used for heating purposes.
Hot water
If measures for retaining heat, as described above, have been implemented and a building fulfils a low-energy or passive-energy standard (heat demand per m² floor area is not more than 15 kWh per annum), the domestic hot water demand will be equally large or even exceed the heating demand. As elderly people generally require more water for washing clothes and dishes, from an ecological and economical point of view it makes more sense to reduce hot water consumption, for example through savings and the use of more efficient fittings, than to further optimise heating energy demand. The remaining heating energy demand can, for the most part, be covered by solar energy using one of the aforementioned active solar heating systems. These are also well-suited for hot water heating, more so in fact than as an energy source for heating (only larger installations are able to provide more energy than required for hot water provision in the winter months).
As a rule of thumb, 1 m² collector surface area is required per inhabitant for hot water heating, with three to four times as much for additional room heating provision. The necessary heat reservoir should be dimensioned for the respective needs. The location of such reservoirs, which can sometimes be more than a storey high, should be considered in the initial planning phases. Heat pumps can be used to utilise ground water or geothermal energy for hot water heating. Thermal collectors are now available in technologically advanced forms and, given the steadily increasing energy prices, represent an economically viable means of covering around 60% of the hot water demand of elderly people.
Electricity
In traditional housing, electricity consumption represents the smallest part of the overall energy consumption. Following the examples above, ecological measures can here too be economically implemented. A kilowatt-hour of electricity cannot, however, be compared directly with a kilowatt-hour of heating. This higher level of energy requires more primary energy expenditure for its production and compared with thermal energy should be multiplied by a factor of three in order to be comparable from an ecological point of view.
In the past older people traditionally consumed less electricity than younger people as they made less use of technical equipment such as computers. More recently older people have begun to make increasing use of today’s modern electronic technology and in future they will use these increasingly to compensate for physical deficiencies. As they require more light as their eyesight deteriorates, it will become increasingly important when building for the elderly to provide ecologically-friendly electricity at a constant and affordable price. Electricity – as a higher order form of energy than heat – will become a particularly sensitive form of energy required for household use.
The principle of photovoltaic solar use
Here too the locally available energy source is once again the sun, which can be converted directly into electricity using photovoltaic collectors. This form of energy extraction is comparatively expensive. In practice only around 10% of the solar irradiation can be converted into electrical energy. By comparison, thermal collectors have a conversion rate of around 50-60%, passive solar gain around 90%. One option is to use photovoltaic solar collectors to serve multiple functions (greater economic feasibility), for example as shading elements for passive solar glazing. Photovoltaic collectors (PV) should be arranged at a shallow angle as the summer sun from above is much stronger than the lower winter sun. They should also be well ventilated as most PV technology becomes less effective at producing electricity as their temperature increases. Photovoltaic should therefore not be integrated into the building but be installed as an additive measure.
Electricity can also be generated using combined heat and power systems (generators which in addition to generating power provide heat as a by-product). One should prevent energy generation methods in the thermal energy sector from incurring energy requirements in the more ecologically-sensitive electricity sector, for example as a result of the need to power pumps and control systems for the aforementioned thermal collector systems. Here the additional electricity demand should as far as possible be covered on site. If there is no possibility or insufficient possibility of generating electricity onsite, one should attempt to derive the remaining power using electricity from alternative power sources such as wind, biomass, small power plants or similar.
Air conditioning in summer
Although old people generally find higher temperatures more comfortable than younger people, the prevention of overheating in summer is just as important for one’s quality of life as heating in winter.
In most cases, protection against overheating in summer for all generations in Central European climates can be achieved using appropriate building constructions alone. The most important criteria is sufficient insulation (as it is for warmth in winter), a high thermal mass and the reduction of passive solar gain in summer. A high thermal mass allows the cool night-time temperatures to counteract the heat of the day and avoid temperature extremes (the absorption of warmth reduces temperature fluctuations). All translucent building elements (such as windows) must be well shaded, in particular east and west-facing windows which can lead to overheating. Internal sources of warmth (for example, lighting and technical equipment) should likewise be minimised through the use of low-energy lamps and equipment. Finally, night-time ventilation should be ensured (including adequate protection against rain, burglary and insects) to allow the entire mass of the building to cool down overnight.
In addition to these passive measures, ground water or geothermal cooling can be used to keep building elements cool (water cooling pipes are laid inside massive parts of the building construction) or via an earth-air heat exchanger to pre-cool fresh air as it enters the building. If incoming air is passed over water surfaces, this too can have a cooling effect. Only in special circumstances – and when all other methods have been exhausted – should additional active measures be taken, which will consume energy. In such cases, existing installations should be utilised wherever possible, for example solar water heaters, which in conjunction with new technology can be used at relatively low temperatures (such as those provided by flat panel collectors: under 100˚C) for cooling purposes. Similarly, PV collectors can be used to power conventional air conditioning equipment.
Automatic vents at the highest point of the building for night-time ventilation
The role of the residents
The final most important factor for the efficacy of all the measures described above is the people for whom we undertake such measures: the residents. Passive measures in particular are largely dependent on the behaviour of the inhabitants. Residents should understand, value and experience the benefit of the ecological measures undertaken. The most valuable medium for communicating this is the architecture of the building itself. Its experiential and communicative qualities play a decisive part in creating a sense of well-being for the residents.
Solar architecture in particular offers an opportunity to communicate technology and to turn technical advantages into beneficial qualities for living environments. Old people often suffer from orientation problems or are unable to see as well as they used to. Sunlight (see passive solar utilisation) can be used to guide orientation. Daylight is always better suited to people’s needs than artificial light, and people who are bedridden benefit greatly from a view out into the countryside. Lastly, natural building materials are advantageous not only from an ecological point of view but also because they are non-toxic, thereby improving conditions for old people who are generally less resistant to toxic substances than younger people.
Maintenance and modernisation
From an ecological as well as energy balance perspective, maintenance and ongoing modernisation is an equally important factor as the construction and running of housing for the elderly. Flexibility and adaptability are key contributors to sustainability. Buildings for old people should therefore be easily adaptable to changing uses and requirements (which we may not yet be aware of) and easy to repair, for example by separating structure, infrastructure (water, electricity etc.) and furnishings so that these can be repaired or renewed separately according to their different lifetimes. The relevance of maintenance and modernisation is underlined by the fact that over an 80-year period, almost one and a half times as much as the original building costs are expended on the upkeep of a building.
C | Demolition of the building
The demolition of a building can only be undertaken without environmental reservations if a building has been built according to the principles of building biology from the outset. Building biology is a prerequisite for ensuring that the demolition and disposal of a building can be undertaken with minimal energy expenditure – a process that already begins on the construction site (disposal of waste material from the building site). In the planning and realisation of buildings the following hierarchy of priorities applies: avoidance of waste, recycling and utilisation of waste, followed lastly by the ecologically appropriate disposal of waste. Measures include limiting the variety of different materials used, the coordination of the lifetime and usage periods of building elements, the use of recyclable building materials, the avoidance of composite building materials, clear product declarations and so on.
Only when the entire life cycle of a building has (next to) no environmental impact have we managed to successfully balance energy usage, protect the climate and environment and, not least, build sustainably for the elderly.
J. Fechner (ed.), Altbau-Modernisierung – der praktische Leit-faden, Berlin, Heidelberg, New York: Springer Verlag, 2002.
M. Hegger, M. Fuchs, T. Stark, M. Zeumer, Energy Manual: Sustainable Architecture (Construction Manuals), Basel, Boston, Berlin: Birkhäuser, 2008.
G.W. Reinberg, M. Boeckl (eds.), Reinberg – Ecological Architecture – Design – Planning – Realization, Berlin, Heidelberg, New York: Springer Verlag, 2008.
G.W. Reinberg, Offenes Wohnen im Alter – Pensionisten- und Pflegeheim St. Pölten, Vienna: Österreichischer Wirtschaftsverlag, 2001.
Originally published in: Eckhard Feddersen, Insa Lüdtke, Living for the Elderly: A Design Manual, Birkhäuser, 2011.