Kitchen design

Green roofs

Non-conventional construction - earth, clay, straw & hemp

Green materials


   Kitchen Design  


Planning a Kitchen Layout

Before you start imagining the finished product you will first need to draw up an overall layout, preferably on squared paper, and position the services (plumbing, electricity, gas point) and also the windows and doors. Remember that services can be moved if necessary, but it can be costly to do.

There are three main zones within a kitchen - food preparation, cooking, and cleaning up. These correlate to the main work sufaces (and fridge/freezer), the cooker and the sink. These zones should make a triangle called the Work Triangle. Even though the sides of this triangle do not need to be of equal length they should not normally be longer than 6.5m (6500mm) and there should be no obstacles along the length of the sides of the triangle.

Remember overall keep the design simple and make sure it works for you. You will probably be spending a lot of time in this room so make it work.

Making Your Kitchen Plan

Once you have drawn up your scale plan of the kitchen on squared paper with all the relevant points marked (e.g. doors, windows, services etc) you should cut out shapes that represent the different sizes of cupboard available and also ones to represent the appliances (cooker, hob, fridge, freezer, sink etc). This makes it easier to move things around if you are not happy with a design.  

Once you are happy with your design you should be able to work out exactly how many floor and wall units you require and also calculate the length of worktop required. Remember with worktop that you should avoid any joins and therefore you will need more worktop than the total length of worktops on your design.


Buying Your Kitchen

There are 3 main options for buying a new kitchen.

  • Completely DIY - buy the units flat-packed, and install them yourself
  • Partial DIY - buy the units flat-packed, build them and have someone install them for you
  • Design and Fit - bring someone in to design, build and fit the kitchen while you put your feet up!

Of course the main reason for choosing any of these options is budget, with the options generally becoming more expensive as you go down the list. This isn't always the case and if you have specific requirements it may be better value for money to go for the last option.

Take a look at our featured companies to see what options they have available. They have a large range of kitchens styles from traditional to contemporary.

Pictures Courtesy of Baltic Kitchens



Green Roofs

Contrary to popular opinion, you don’t need to mow, or even maintain, a grass roof. It can be left to grow and attain a balance of different plants. The shallow depth of soil will limit growth and vegetation will go brown and die back during dry spells in summer.

The main drawback is the need to design the roof structure to support large amounts of heavy earth (especially when wet) which can substantially increase costs - it's not unusual to end up with as much as 400mm depth of topsoil on the roof weighing 50 tonnes or more. Lighter weight systems use plastic mesh containing a seeded growing medium or plants rooted in a plastic mat, but they are still relatively expensive. This reduces the cost of a structure than has to support large amounts of heavy earth. 


Benefits of green roofs

- They soften the building's visual impact.

- The earth layer acts as thermal buffer to keep building warmer in winter and cooler in summer.                             

- Green roofs slow water run-off.  Hard surfaces cause large volumes of storm water run-off. This causes problems in areas such as London where no separate storm-water system, so if there’s heavy rain the treatment works (which have limited capacity) can’t cope with the high flow. This means that in periods of  exceptionally heavy rainfall, large quantities of untreated sewage discharges into Thames.


Green roof decisions

There are several questions you need to ask when designing a green roof:

* Do you want an ‘intensive’ green roof? This is a more expensive opton.

* Do you want it  based on soil?  This is heavy, especially when wet, and the extra weight increases costs for the supporting roof structure.

* Alternatively, would you consider a lightweight system with plants rooted in a plastic mat?

* Will it incorporate some means of retaining water in a mat or profiled underlining?

* Will it be turfed - or seeded with a varied selection of plants (e.g. economical wildflower and grass seed in soil that naturally dries out in summer looking brown and shaggy)?


Building a green roof

This is a description of how a flat green roof can be constructed:

Flat roof joists typically 200mm deep are first installed as per engineer's calculations (to support the necessary green roof loadings). These are fully filled with blown-in insulation. Battens are then added across tops of the joists to form a ventilation gap. Then a deck of OSB is fitted.  OSB is similar to chipboard but can be used for structural purposes like plywood but cheaper. It is made from timber waste, and is quicker, cheaper than t&g boarding.

A rooflight can be fitted, for example atriple glazed dome.

Once the deck has been installed, lay a single ply membrane (of TPO) loose over the roof deck, not fixed down to it, but draped over it like a tablecloth. This is ballasted with shingle or  soil & turf,  protecting the membrane from damage and from the sun’s UV radiation which would make it brittle and prone to cracking. It also keeps membrane at even temperature, preventing puddles from forming. (puddles keep membrane cool but dry area around can get hot = differential expansion at edge of puddle = crack/leak).

The membrane can move with temperature changes, and timber deck can move with changes in moisture content thru seasons, without stresses where bonded together. Overlapping joints in some PVC roof membranes can be sealed with a hot-air gun. The edge of the membrane is retained by a capping that still allows it to move independently of the deck. Adequate ventilation is needed.


The soil mixture is then carried up to roof in buckets and spread to 80mm thickness on top of an underlay to protect the roof membrane - some green roofs have as much as 400mm topsoil, adding massive loadings.

It is important to use soil of relatively poor fertility to encourage drought-resistant wild flowers and grasses which can survive long, hot, dry summers and discourage those that can’t. Drought-resistant species can survive long summer need an impoverished soil – too rich soil attract lusher species that die off permanently when it gets dry. Roofs can seeded with grass-seed mix.


Pitched green roofs

A green roof can be at any pitch from flat to 30 degrees, but steeper pitches need netting or battens to prevent soil or turf from sliding down the roof.  Root matting laid within the turf helps prevent soil being washed away.

Or else, once seeded with a grass-seed mix, cover with bio-degradable jute fabric through which plants can grow.  Once the plants are established this will rot away.

A turf roof can use turf laid on around 75mm of soil on a layer of geotextile membrane which protects the single-ply roof membrane.


Non-conventional Construction -  Deep Green Materials


Modern earth building

If you want to ‘out-eco’ Dick Strawbridge, traditional ‘mud wall’ construction can be used for new building. Cob is the most common form of earth building in Britain, and is widely found in Devon.  Cob is made from earth mixed with straw and course sand, sometimes with dung added to reduce cracking problems during drying.For soil to be suitable for cob, the earth should have a clay content of between 10% and 30%.

Cob walls are built on a plinth of local stone above splash zone and incorporating a DPC. The cob is built up in layers about 0.5m high to form walls 600-900mm thick These are left to dry for a couple of weeks then trimmed and lime rendered inside and out.

Mud is applied to walls built up in layers around of 450mm  and shaped by hand without use of formwork. Finished walls are about 600mm thick and the mix takes about a fortnight to dry when it can be plastered with lime render. The mix can be improved by addition of straw and course sand.

Even relatively thick cob walls have less good thermal insulation than you might expect, with a typical U-value of about 0.45, and need additional insulation.

Walls about 600 to 900mm thick are built up in layers about 0.5m high shaped by hand without use of formwork or sometimes with the help of temporary shuttering. Each layer allowed to dry for a couple of weeks before the next one. A good-quality cob can survive quite well without rendering, but normally it is coated with a lime render inside and out, made from quicklime putty and course sand, followed by a lime wash. These traditional coatings have the important property of being porous or ‘breathable’, so that any moisture that gets into the cob can evaporate out.  Cob walls are extremely durable but if moisture gets trapped can start to crumble. So avoid modern coatings, such as cement render, gypsum plaster and vinyl paints, which do not allow the cob to dry out after a spell of wet weather. Built on a plinth of local stone above splash zone and incorporating a DPC.


Rammed earth

Similar to cob in that the main component is subsoil. Rammed earth walls are constructed by the compacting (ramming) of moistened subsoil between temporary formwork panels. When dried, the result is a dense, hard wall with good thermal mass. According to the old saying, 'all an earth wall needs are good boots and a good hat to keep it dry'. So walls are best constructed on a plinth of rubble stones, sometimes known as 'grumplings'. These prevent rising damp and offer protection from rain splash-back and surface water – the taller the better. The downside of earth walls is that not all soil types are appropriate and unless skilfully built there are concerns about durability, plus external walls require additional insulation. Many of the shortcomings can be averted by the addition of a small amount of cement is often added as a stabiliser, but this detracts from its eco-credentials.


Clay lump

Also known as ‘Adobe’ clay lump was used in East Anglia in c18th. Mud is moulded into bricks which are dried, bonded together with mud mortar and rendered with mud plaster. This is a quicker way of building with earth, compared to cob or rammed earth. Mud construction has been developed with the CINVA ram which applies high pressure to make compressed soil blocks.


Modular contained earth

Here, old tyres or hessian sandbags are filled with earth and the finished walls rendered with mud or lime plaster. Tyres can take 3 or 4 wheelbarrows of soil



Straw is a cheap waste product. Straw bales are too dense to burn and don’t support combustion, and too dense for rodents. As with earth construction it is vital the straw remains dry, so a good foundation is needed to protect against rising damp.

Straw has similar insulation properties to other materials, but has substantial thermal mass. It creates very thick walls, typically 600mm (or thinner 360mm if laid on edge as non-structural infill)

Straw can be used either in the form of:

*  infill within a post and beam structure, typically a timber frame house with a layer of straw bales on the outside, which provides thermal insulation to the walls.

*  structural bales that support the building. Stacking up straw bales as the structure, and plastering them inside and out with a lime render to create a sandwich wall, is a very simple method. But complications can arise because straw can settle over time under load causing cracking of render, which in turn can let damp in as rain penetration. A rainscreen cladding such as timber weatherboarding is advisable. Bales can be pre-compressed using steel rods and planks of wood.



Hemp stalks mixed with hydraulic lime to produce a stiff mixture. This is packed into a plywood formwork as infill between a post & beam timber frame structure, to form a wall, finished in lime render.

Hemp is very porous to moisture and must be able to ‘breathe’. Thermal performance is better than masonry houses. Hemp walls are built on top of a brick plinth (using lime mortar) raising the hemp above the splash zone.


Green materials



Good quality softwood should last indefinitely provided it is not permanently damp. It should not decay if the design allows it to dry out after getting wet, for example by setting windows well back from the face of the building. To prevent decay and avoid the need for treatment with wood preservative chemicals:-

-         Specify wood classified as ‘durable’ or ‘moderately durable’ and avoid sapwood

-         Ensure your design allows water to escape freely and not collect near timber surfaces

-         For localised protection at weak points (such as at the base of windows) fit solid boron implants. Boron is a virtually harmless fungicide that only becomes active when the moisture content of timber reaches above 20% (i.e. when it becomes at risk from decay)


Wood preservatives are one of the major sources of toxicity in new homes. NHBC no longer require interior timber to be treated. Where timber does need to be treated the best advice is:

-         Use water-based treatments, not solvent based ones.

-         Specify factory treatment rather than site application of preservative

Avoid creosote, CCA, PCP, TBTO and bi-fluoride compounds.



Cellulose Insulation    See



The Code for Sustainable Homes


The Code for Sustainable Homes measures the sustainability of a new home against nine categories of sustainable design, rating the 'whole home' as a complete package. The Code uses a 1 to 6 star rating system to communicate the overall sustainability performance of a new home.

The Code for Sustainable Homes sets minimum standards for energy and water use at each level and, within England, replaces the EcoHomes scheme, developed by the Building Research Establishment (BRE).

The Code will provide valuable information to home buyers, and offer builders a tool with which to differentiate themselves in sustainability terms.

Guidance on how to comply with the Code can be found in the publications The Code for Sustainable Homes: Technical guide, which sets out the requirements for the Code, and the process by which a Code assessment is reached, and The Code for Sustainable Homes: Setting the Sustainability Standards for New Homes which sets out the assessment process and the performance standards required for the Code.


Depending on the technology selected, renewables like solar electricity can be an extremely effective way of reducing carbon emissions.

For example, a standard photovoltaic system can reduce CO2 emissions by over 30% on a typical 3 bed end of terrace house built to Part L 2006 standards. With the Code for Sustainable Homes requiring a CO2 reduction of 25% for Code Level 3, or 44% for Code Level 4, an installation such as this makes a huge contribution to CO2 reduction targets.


The Code is a points-based system and the required reductions in CO2 emissions, whether through passive measures or the installation of renewables, will earn you points towards your Code Level (5.8 points for Code Level 3, and 9.4 points for Code Level 4).

However, if you have achieved your reductions using renewable energy, then further points are awarded; 1.2 points if 10% of energy demand is met through renewables, or 2.4 points for 15%.


Home energy sources


The CO2 emission factor used is 0.527 kg / kWh [Defra, 14]

This includes an allowance for the 7.5% of losses on the national grid [Defra, 14] and some other inefficiencies that occur before electricity reaches the end user. Other calculators that use a smaller value (e.g. 0.43 kg / kWh [2] [5] [6]) appear not to allow for grid losses. The average electricity consumption is 4,800 kWh per household [36].

A smaller than average household is taken arbitrarily to be 3,000 kWh (i.e. roughly two-thirds of the average), and a larger than average household to be 7,000 kWh (i.e. roughly 50% more).

Approximate figures: small house: 1,650 kWh; medium house: 3,300 kWh; and mansion: 5,000kWh.
Domestic electicity use (excluding heating) is made up of [Defra, 14]:

Average domestic electricity use
(excluding heating)
Cold appliances 18%
Cooking appliances 15%
Wet appliances 15%
Lighting 19%
Consumer electronics 19%
Domestic ICT 9%
Other 5%
Total 100%

'Green' electricity

In the UK, the regulation of electricity generated from renewable sources is complex - every electricity supplier is required to either buy some electricity from renewable sources, or to buy certificates from other suppliers who have bought from renewable sources, or to pay a fee. This system is designed to encourage investment in renewable sources, but it results in the trading of certificates that is almost impossible for the ordinary consumer to understand, since the 'greenness' of electricity can be sold to two or even three different customers by some suppliers.

The National Consumer Council has written a guide [39], and concludes that many suppliers offering green tariffs are doing little more than meeting legal requirements, and are not delivering the environmental benefits they claim. The guide says that even the best tariffs will reduce CO2 emissions by only a faction (because most of the certificates are still sold on to other suppliers) - the cost of not doing so is put at around £200 for the average household, which (it is judged) few households will be prepared to pay.

The calculator therefore assumes the reduction in CO2 emissions from the best 'green' tariffs to be just 25% - partly from a reduction in CO2 emissions, and partly from the influence on Government policy arising from the demonstration to the Government that some consumers are willing to pay a premium to reduce their CO2 emissions. The best tariffs are defined according to those ranking highly on Ethical Consumer Magazine's Ethiscore ( viewed 2 March 2008) as follows:
  • Good Energy electricity
  • Ecotricity New Energy Plus
  • GE 100 electricity tariff
  • Ecotricity electricity
  • GE 10 Electricity tariff
  • N.Ireland Eco Energy green tariff
  • RSPB/Scottish & Southern electricity

Natural gas
Most modern gas meters measure gas in cubic metres (m3). The energy contained in gas is measured in kilowatt-hours (abbreviated to kWh) and for natural gas is 11.2 kWh per cubic metre.

Older gas meters measure gas in hundreds of cubic feet - 100 cubic feet equal 2.83 cubic metres. So the energy contained in gas measured by an older gas meter is 31.7 kWh per 100 cubic feet.

The CO2 generated by burning natural gas is 0.185 kg / kWh [DEFRA, 18] .In 2006, the total UK gas supplied was 1,047,000 GWh, but of this 79,400 GWh was 'Energy industry use' and 12,000 GWh was 'Losses' (see source [36] Table 4.1). These total inefficiencies were 91,400 GWh, i.e. 8.7%, and so the CO2 emissions need to be adjusted by this amount from 0.185 to 0.203 kg / kWh.

The average UK annual gas consumption is 16,000 kWh per household [36], but per meter is 18,000 kWh [36] (a larger amount as not every household has a supply of natural gas).

A smaller than average household is taken arbitrarily to be 12,000 kWh (two-thirds of the average gas meter), and a larger than average household to be 27,000 kWh (50% more).

Approximate figures:  small house: 10,000 kWh; medium house: 20,500 kWh; and mansion: 28,000kWh.


Heating oil

The factor assumed is 2.96 kg CO2 per litre of burning oil (also known as kerosene or paraffin).

The CO2 emissions from the burning of oil (from source [14]) is 2.52 kg CO2 per litre (which is equivalent to 3.15 kg CO2 per kg, and 0.245 kg per kWh) [14]

This needs to be adjusted for the fossil fuel used in the extraction of oil and in refinery inefficiency, which together gives an inefficiency of 15% (see car sources page), giving a figure of 2.96 kg CO2 per litre.

Other sources give:
  • 2.5 kg / litre [NEF, 2]
  • 3.0 kg / litre [ML, 6].




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