Sustainable homes

It’s easy to fall into the trap of designing a green home without considering the impact of your outdoor spaces. Here, Tim Pullen outlines how to create a perfectly green garden

Tim Pullen explains how to embrace the great outdoors

Sustainability does not begin or end at the front door, or even at the back door. It is about minimising our impact and the garden has a very significant role to play in that; sustainable landscaping is as much a part of a sustainable home as natural insulation. Landscaping is a significant element of any home. It can consume as much as 20% of a project’s total budget, be a resource, add interest, extend living space and encourage biodiversity. It can make or break the kerbside appeal. As such, it perhaps warrants as much consideration as the interior of the house does.

One of the principal, and increasing, problems with an interesting garden is its demand for water. Hosepipe bans are now commonplace in the UK, as are floods. Rainwater harvesting and grey water recycling come into their own here, providing, to put it simply, the luxury of being able to maintain a healthy garden legally and with a clear conscience.

Here, we explore some of the key ingredients of creating a ‘greener’ garden.

Permeable surface treatments

Our outdoors have to fill a number of functions. Not the least of these is somewhere to put the car (and charging point as we move towards electric cars), which in turn means hardstanding with a permeable surface treatment. Beyond the need to comply with the Regulations, the arguments for limiting surface water run

off using permeable treatments are not easy to grasp. It’s a bit like keeping chickens; they are lot of trouble with no obvious benefit — until all the shops run out of eggs. In recent years we have regularly experienced both floods and hosepipe bans.the effect of permeable hard surfaces is not immediate or obvious, but it is real.

Typically, gentle rain produces 90 litres of water per hour on an ‘average’ driveway, while a summer storm might produce 630 litres. The effect of permeable surface treatment is twofold: it significantly reduces the surface water leaving the property, thereby reducing the potential for flooding, and it retains water on the plot, reducing the need to irrigate with mains water.

For infrequently used areas, footpaths and the like, barks and pebbles are often the cheapest and most effective solutions, closely followed by crushed rocks and gravel. If you need something a little sturdier – to accommodate vehicle traffic, for instance – there are a range of options, including permeable concrete, asphalt, tarmac, self-binding gravels and grass pavers, as well as standard blocks and slabs laid on a permeable substrate with wide gaps between them. (Read our buyer’s guide to driveways next month.)

The lawn: haven or green desert?

Gardens create visual appeal, give a sense of space and perhaps even convey status, but perhaps one of their principal functions is as a leisure space and/or a play area. It is often a lawn that fulfils that function.there are many of us who take pleasure in a perfectly mown lawn, and so, when we are designing the garden, we lay most of it to grass. A good lawn will require watering around 5litres/m2/ week throughout the summer in order to maintain that wonderful, stripedgreen, ‘Pimms in the midday sun’ look. This means that even a 10m x 10m lawn requires around 14,000 litres of water in each summer month.

The grass is typically a single species and not allowed to flower or seed, so it is of limited interest to invertebrates and birds. Almost no organic matter is returned to the soil because the grass clippings are removed and autumn leaves swept up. As a result, lawns can require the annual application of fertilisers, weed killers and conditioners to maintain that super-green colour, keep the grass growing and to ensure that nothing but grass will grow.

You may note that this is not perfectly in keeping with the ideal of a sustainable home, so we have to ask ourselves what the lawn is for, and whether there are alternatives. If we are looking for a play area – soft for the kids, good for barbeques and sunbathing – then there are options, as shown in ‘Beyond Lawns’ (left). Combine

‘‘ The effect of permeable hard surfaces is not immediate or obvious, but it is real

these garden systems in one space and you’ll have ticked all the boxes, creating a garden that is ecologically sound, meets all the functional needs, has a minimal water demand and looks beautiful.

Green roofs

Green roofs can help and go a long way to reducing the footprint of the house. They are also one of the more visible signals that this is a sustainable build, and they have some significant benefits, absorbing both heat from the sun, CO2 and up to 70% of the water that falls on them. Most importantly, they help to replace the ecology that the building stands on. However, they are a fundamental design feature that is not to be taken on lightly; it needs careful planning. Even extensive roofs (see left for more information) will eventually get naturally seeded by birds and insects and need care and some maintenance.

A pond is perhaps the greatest ecological improvement we can make to our home. As well as being a significant visual feature, it provides food, water, shelter, and a breeding opportunity for wildlife like dragonflies, frogs, and birds. And, beyond a few plants in and around it, we don’t have to do much more: nature will take care of the rest.

Natural swimming pools

It may be that you want a pond big enough to swim in, and that too can be natural and self-maintaining. It’s probably not for everyone, but anyone who has experienced the luxurious sensuality of swimming in a lake will understand what natural swimming pools are all about. Swimming pools generally are becoming increasingly popular, but conventional pools are ecological deserts; they need a lot of energy and use fairly unpleasant chemicals.

Natural swimming pools use plants, natural filtration and micro-organisms in reed-bed ‘technology’ to clean their water and are consequently chemical free and use almost no energy. They are essentially a swimming pool and pond combined, with a physical barrier between the two to keep the swimming area separate from the pond area — known as the regeneration zone. If it is for you, check out www.clear-water-revival.com for all the fun of ‘wild swimming’ in your back garden, and read our in-depth guide to building a natural swimming pool next month.

Hopefully the features discussed here have given you your own thoughts about how to create your own sustainable outdoor space. May you enjoy every aspect of it to its full potential.