Why use plants in buildings?

Interior landscaping has become increasingly popular during the last 30 years. Most architects now include plants in their design specification for new shopping centres, office complexes and other public areas, and they are something we all expect to see when we walk through the door. But what is it about plants that makes them such an important building accessory?

The most obvious answer is that they look attractive – who can fail to be charmed by the graceful arch of palm leaves or the exotic beauty of orchids? However, recent research has shown that the value of plants goes far beyond the purely aesthetic. Plants are actually good for the building and its occupants in a number of subtle ways and are an important element in providing a pleasant, tranquil environment where people can work or relax.

The key uses and benefits of plants are summarised below. For more detailed information follow the links in the text and/or select a subject from the menu on the right-hand side of this page.

They help to reduce sickness absence.

Absence from work cost British business £11.8 billion in 2002. Job dissatisfaction and low morale can be prominent factors in short-term absence and could account for as much as 15% of all reported sickness absence. Employers can tackle this most easily by re-examining people management policies and the working environment, to see what can be done to improve staff productivity and well being. If companies with the worst absence rates could meet average levels, the UK economy would be £1.9 billion better off. (Ref: “In sickness and in health”, Business Voice, June 2003, p11.)

The humble plant may be part of the solution. There is now a wealth of evidence to show that putting plants in buildings can significantly reduce absence from work. It isn’t necessary to fill every available space with a plant to achieve this; just a few good-quality specimens located near to where people work and take their rest breaks seem to suffice. The reasons why this has a beneficial effect are probably a subtle but complex mixture of the physiological (improved humidity, reduced noise etc.) and psychological. Being around plants certainly seems to reduce stress and engender a feeling of well-being in most people, a benefit that is even more acute if correct lighting is in place. The fact that the employer has been prepared to spend money on something that has no obvious function other than to make the workplace more attractive may also be a contributing factor, by sending a signal to staff that management cares!

They help to increase retail spend. 

The following two extracts from papers written by an American researcher and a British shopping centre manager highlight the importance of plants in retail environments:

“Retailers have long understood the importance of store environment in enhancing the shopping experience. The outdoor landscape can be a seamless extension of shop interiors, providing indoor/outdoor continuity for a positive shopping experience. Urban forestry can play an important role in business districts. Interior plants and landscape may create store interiors more favourable for retail activity.” (Ref: “Retail and Urban Nature: Creating a Consumer Habitat”, K.L.Wolf, at the People/Plant Symposium, Amsterdam, 2002).

“The annual cost of maintaining the planting of the centre is just under £ 1/4 million, or 4.3% of the annual service charge. The fact that this massive sum of money has never been queried is of vital importance. It implies a complete acceptance of the existence of plants within and around the centre as a fundamental factor in the success of the centre. A subjective ingredient of the centre too important to touch.

"Through the medium of plants the centre successfully translates outside to inside, relaxes almost everybody, all ages and types of people relate to the atmosphere. The result for the public is a perfect environment for the purposes of shopping and leisure. The result for the tenant is the second highest net profit per square foot in Britain.” (Ref: “Am I Running a Greenhouse or a Shopping Centre?”, J Bryson, Centre Manager, Metrocentre, Gateshead, England at the BALI seminar, London, 1992).

Although much of the evidence is still subjective, it is clear that professional retailers firmly believe that plants are an integral part of the selling environment and are prepared to allocate the space and resources to accommodate them.

They make buildings look more attractive and welcoming.

Perhaps the most obvious reason for installing plants and one that is backed up by research. A postgraduate study carried out in a London hospital in 1995 provided clear evidence that people do react more favourably to a building when it contains plants than when it does not. Hospital visitors were asked to respond to a descriptive choice test using twenty pairs of bipolar adjectives (quiet v noisy, cheerful v gloomy etc.). The results showed that when plants were present in the reception area of the hospital, users perceived it to be:

17% more ornate 17% more interesting 17% more cheerful 16% more welcoming 15% more relaxing 11% less stressful 11% more expensive 11% tidier 8% quieter

There were no negative findings and all the results were independently verified as being statistically significant. (Ref: “Human Responses to Interior Planting”, J.V. Stiles, PhD, Oxford Brookes University, 1995).

They make a design statement. 

Interior landscaping is becoming a fashion-driven business, where as much effort is now put into the design of the containers, accessories and overall “look” as into plant selection. The current trend is for minimal, clean-looking containers and strongly shaped architectural plants.

Tall, tapered containers in galvanised steel or aluminium and the “stone” look are particularly popular. Simplicity is the key – underplanting and the jungle effect are definitely out!

(See also our article on plants making a design statement.)

They can be used for wayfinding.

In many buildings there is a need to channel pedestrian traffic towards significant landmarks, such as exits, check-in desks, escalators and common passageways. This is particularly important in premises with large, open areas such as those found in airports, shopping malls, hospitals and many large offices. Plants offer an attractive and practical solution, providing a living barrier that gently guides people to where you want them to go. (See also the article on wayfinding and signposting.)

Choosing the right plants and containers for this purpose is very important. Spiky plants or those with sharp-edged leaves would clearly be inappropriate in an area designed for heavy pedestrian traffic flow. Containers need to be robust, take up the minimum of floor space and in some situations be linkable to form an impenetrable wall.

They improve the indoor environment.

There is now general agreement within the scientific community that plants improve the indoor environment, and are useful weapons in the fight against the modern phenomenon known as sick building syndrome (SBS). No specific cause of SBS has been identified, but poor air quality, excessive background noise and inadequate temperature and light control are thought to be important factors. Because plants have a large surface area and exchange water and gases with their surroundings, they have a unique ability to tackle many environmental problems. In particular, plants can:

• Reduce levels of carbon dioxide, which can accumulate in buildings from the breathing of its occupants and the by-products of heating systems and electrical equipment.
• Increase relative humidity, which should be between 40% and 60% RH for maximum human comfort.
• Reduce levels of certain pollutant gases, such as formaldehyde, benzene and nitrogen dioxide.
• Reduce airborne dust levels.
• Reduce air temperatures.
• Reduce background noise levels.

In short, every plant is a miniature air-conditioning system!

They can be used to soften/hide less attractive features.

However well designed, most buildings have features that are best kept covered, such as service areas, storage facilities and harsh structural elements. Plants, with their wide range of size, shape, habit and leaf form provide an elegant solution that is both attractive and functional. Containers like the patented Rentokil 'Lynx' system were developed with this purpose very much in mind. The interlocking pots can be used to create plant “walls” and create a continuous area of greenery around pillars and other immovable obstructions.

They can be used to break up large open areas. 

The vast expanses of open space found in airports, stations, shopping malls and open plan offices look soul-less and intimidating unless “broken up” by familiar objects. Plants are the most common solution, providing natural divides and reference points that make the space look more friendly and inviting.

They are educational.

Bringing a little of nature indoors, especially in urban areas where people may not have had much exposure to plant life can be both stimulating and educational. Where else, other than the tropical plant houses of botanical gardens, will you see the variety of exotic and unusual plant species usually on display in shopping centres and large office atria? The increasing use by many establishments of plant labelling, with information on species, origins and history, is increasing this benefit even further and encouraging people to take more interest in their surroundings.

They can be used to reflect national or cultural aspects of a business.

In the multinational world of commerce, every country has businesses, whether banks, hotels, manufacturing facilities or airlines, from every corner of the globe. Many of them are proud of their origins and wish to reflect it in the style of building they occupy and the way it is furnished. This doesn’t always just apply to the decor, fittings and building design; companies are increasingly turning to interior landscaping to make a national or cultural statement. The stones, water and plants that form the basis of Japanese gardens in many Far Eastern organizations are an obvious example. So too are the native flora and accessories used in Rentokil Tropical Plants’ “Australiana” range and the New Zealand containers designed and manufactured by local artists.

New Zealand 'Uku' container	'Australiana' - Australian native plants in a large interior feature bed

In conclusion

Research clearly tells us that people do respond positively to the presence of plants in buildings. Healthy, well-maintained plants in well-designed displays enhance the character and appearance of a building and improve the psychological and physical well-being of its occupants. Above all, interior landscaping has been shown to be a sound investment by reducing sickness absence, improving mental agility, increasing use of communal facilities and positively changing a person’s perception of a building.

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