Sustainability

We live in changing times that bring with them many challenges. Climate change, together with pressure on living space via urban expansion, means that the role the landscape plays in our lives becomes more and more crucial. The desire for green space within the built environment is intensified and urban greening becomes a way of keying into our spiritual lives via an emotional connection with the land.

So what does this mean for the future of garden design? Carbon neutrality has become the holy grail with even carbon neutral skiing holidays now being offered. If anything the garden designer’s career is safer than it was before but there are new sets of criteria becoming ever more important that he needs to consider in the design of outside space.

When I design a garden, I need to think about the primary carbon footprint left from the usage of the final product. So for example, I might be talking to a client about conversion of a traditional swimming pool to a natural swimming pool and pointing out the reduced energy requirements in maintenance and benefits to biodiversity. I also need to think about the secondary carbon footprint which is more likely to be an issue during the construction phase. Concrete is known to be a CO2 intensive building material so I might want to limit its use; the CO2 cost of soil excavation and removal to landfill is high so I might well be thinking in terms of utilising the fill I had at my disposal within the garden itself with the sculpting of landform being a great option.

The requirements of sustainability need not however compromise great design. Rather, as Dieter Rams points out, the requirements of sustainability become an integral part of what constitutes good design. But they never become the sole aim. My job is to utilise new technology and find innovative ways of reducing energy usage whilst still creating beautiful and desirable spaces where you’ll most definitely want to spend time.

Localism versus internationalism

There’s been a great buzz about encouraging the use of Native species in this country which is great and to be lauded. However when you look at the 1100 British native species compared to the the 20,000 native American spec ies you can see why we mustn’t be too literal about this. Added to which, Exotics are a firmly embedded part of our culture so as climate allows, I see no reason why we shouldn’t use what will grow well in our country and probably thrive particularly in the immediate future.

But the point is that we are looking to our immediate surroundings. Choosing a locally sourced stone will save on CO2. Taking this a step further I could decide to use either reclaimed stone or timber. The source of the material, offset against the distance it comes from may well still make it a viably sustainable choice.

We must also take care in the choices we make about timber. Using FSC (Forest Stewardship Council) approved timber is a good start. The FSC regulate forest management and chain of custody so that certified timber is more likely to have been produced in a sustainable fashion. Perhaps it would be even better to use timber from British woodlands. The practise of coppicing allows for the sustainable use of green oak and sweet chestnut for example, and the whole process actually promotes the growth and survival of these woodlands.

This process of looking to our immediate surroundings also impacts our attitude to food. Why should we eat fruit and vegetables flown half way across the world when we can eat food grown locally. A seasonal approach to cookery is far more sustainable and frankly enjoyable and it also draws us to an awareness of seasonality in the broader context. Different parts of the garden may look gorgeous at different times of year according to what is planted where. But as I stated earlier, climate change is afoot and what we can or can’t grow is changing. We are now looking towards crops of champagne and olives. Some native trees such as beech are dying out in areas where once they flourished and we must adjust the choices we make to accommodate the future.

Water the new oil

Water has been dubbed the new oil and it is with increasing frequency that we are faced with the spectre of water shortages.

Perhaps it’s time to consider alternatives to the quintessentially English lawn that doesn’t fare well under cycles of drought and flooding. A tertiary sward of drought tolerant mixed grasses and wild flowers might be a better alternative or you might simply consider replacing areas of lawn with a low maintenance drought tolerant gravel garden.

However, with changing weather patterns it’s not just water shortage that we need to deal with but also increased flow rates with heavier downpours of rain. So it’s even more important to be able to manage water flow within the garden. Laws designed to do just this were introduced in the form of Sustainable Urban Drainage Systems, or SUDS for short. Put very simply SUDS is about controlling or attenuating water flow. This control over the movement of water enables us to remove pollutants and gently release clean water back into the natural aquafers on site rather than taking water away from site via mains drains so that it may be taken up by trees etc. There are various drainage systems that are SUDS compliant and may be implemented in order to achieve this from the humble soakaway via permeable paving systems to highly engineered rainwater harvesting systems. more than ever, designing a garden is about evolving environmentally friendly drainage solutions which efficiently manage water flow.

Dry gardens

A dry garden consists of drought tolerant plants that will only ever need to be watered whilst they are becoming established at the time of planting. This makes it a great choice for those of you requiring low maintenance gardens and a great sustainable option for reducing water usage in the garden. You won’t need to worry about plants dying during hosepipe bans or while you are away on holiday.

Dry gardens require a sunny aspect as most drought tolerant plants are associated with a warm climate. These plants thrive in poor and free draining soil which should be mulched with a layer of gravel. This inhibits the growth of unwanted weeds and will also help to retain the moisture that is already in the soil.

So what does a dry garden look like? Many of the plants that thrive in a dry garden like to have space around them. This immediately sets a dry garden apart from the more traditional herbaceous border and means that you will often have groups of plants in open space surrounded by areas of gravel . This is ideal for an informal area through which you can wander and really get in amongst the planting. A dry garden might therefore cover a large area and offer a realistic alternative to a lawn. How wonderful to be able to wander through drifts of aromatic planting to an informal seating area where you can read or even just nap. It also becomes practical to include pergola-type structures and sculptural form as you will have the space for these features.

What is even more exciting about dry gardens is the fact that there is a huge range of planting, from bulbs to trees that is suitable for inclusion. Drought tolerant plants often exhibit a glaucous foliage which is grey- blue to green in colour. This foliage might often be thickened as in the case of succulents such as sedum or agave in order to retain valuable moisture. Leaves and stems are often covered in tiny hairs called trichomes which serve to give protection against extremes in temperature and also from insect attack. These trichomes also serve to retain moisture but can be irritable to the skin, as in the case of Fremontodendron californicum.

You often get a pale blue flower with a a grey green leaf and plants such as perovskia “blue spire”, lavandula angustifolia and teucrium fruticans immediately spring to mind. Drought tolerant plants are often aromatic, so a dry herb garden of salvias, rosemary, thyme and catmint is a great idea. There is also a vast array of plants which have great architectural impact and benefit from having space around them. Think of backlit stipa gigantea, huge ornamental thistles and artichokes or of the magnificent giant fennel.

In case you still aren’t quite sold on the idea of a dry garden, there are some great precedents which you can easily go and see. Beth Chatto was the first to famously create a dry garden from an area that originally served as the car park to her gardens and whose soil quality is spectacularly poor. There is also a stunning dry garden at the Savill garden, Windsor and neither are ever watered!

Green walls and roofs

There are other complementary methods of achieving water attenuation and it is worth considering the major role that green roofs and walls have to play in the hunt for sustainable living.

Green walls and roofs effectively become bio membranes and their most visible function is urban greening. Where space is at great premium, the addition of a green wall effectively offers a vertical garden in an otherwise hard, urban landscape. It offers connection between the built environment and the natural world, between mankind and nature. What a great way to create soft landscapes within a harsh urban environment.

Other functions of green walls and roofs are as follows:

Attenuation of rainwater so that we can better control water flow and lose less water.
Thermal insulation, which potentially will lower the cost of heating a building
Noise reduction
Reduction of the Urban heat island effect which is caused in the first place by the reduction of green space via urbanization. Vegetation has a cooling effect on the surrounding air due to evaporation and transpiration.
Improved air quality as a result of natural filtration of pollutants from the atmosphere by vegetation and associated substrates.
Food may be grown on a green roof with kitchen herbs being a popular choice for green walls.
Provision of green space is great for biodiversity offering habitats for insects and butterflies. Green roofs in urban areas are providing great foraging potential to bees.

Green walls may be simply achieved via climbing support. These now consist of mesh screens or cabling systems which can offer vertical greening up to 30 metres in height. The other new and exciting technology for green walls are vertical wall panels which offer either soil-based or hydroponic growing mediums and effectively make vertical gardens possible.

Green roofs fall into three main categories according to the depth of substrate allowable and the desired end result. Extensive green roofs would have a very shallow substrate and are effectively green mats of moss, herbs and grasses. An intensive green roof might have a substrate of up to 400mm and you could grow pretty well anything you like.

Natural swimming pools

Natural swimming pools are a fantastic illustration of how sustainable technology has been brought to bear on the demand for carbon sequestration. Heat pumps taking heat from the ground, or solar panels are used to heat these pools and there is no need for an electrically powered filtration system or the chemicals that go with it as water is filtered biologically. The energy saving is vast and the spin offs for biodiversity are great too. Construction methods have evolved too with concrete no longer the main material used in pool construction.

You can refurbish an existing swimming pool or start from scratch which will give you ultimate control over how the finished product looks as there are a myriad of options to choose from, making it possible to achieve a style that is either sleek and minimalist or more urban sustainable. There is also great choice over the type of filtration system you can use so that you could for example have filtration plants within an area of the pool you swim in or in an adjacent dedicated filtration area.