Interest in eco-friendly homes had never been so high, particularly now that it is largely accepted that our activities are damaging the planet. 

Alderman Stone have and continue to research this exciting new specialism to ensure that consideration and suitability are discussed and incorporated into schemes.

The UK government published its Net Zero Strategy with the intention of reaching net zero greenhouse gas emissions by 2050. 

If you are building and you want it to be as green as possible, there are three main issues to consider: 

• Energy efficiency of the building
• Choice of building materials
• Power generation

Insulating Against Climate Change

It can make sense to insulate new build and extensions more than building regulations require for a cost effective energy saving measure.  If there's a lot of glass in the building (a conservatory, for example),  you may also consider special glass such as Low-E which has a coating that reflects radiator heat back into the room while allowing the sun's heat through.
 
Depending on your chosen building method, you can also install insulation that's not as damaging as fibreglass or some mineral wools. There is now a wide choice made from wool, natural fibres such as hemp, or cellulose from recycled newspapers. Many of these come in the form of blankets or batts than can be cut to size or shape and slotted in, or in a semi-liquid form that's blown into the cavities.

Underfloor heating is another option worth considering. It's very difficult to install in an existing house but installation for new build/extension is a lot easier and can usually be added to the current central heating system.  Whilst more expensive initially than radiators to install,  the water inside only needs to be heated to around 40-50 degrees C, as opposed to the 85-90 of radiators, making running costs lower. In addition, you get even heat throughout the rooms, floors that are warm underfoot, and no radiators to get in the way around walls.

You may also want to choose materials that do not use a lot of resources in their construction, as breeze blocks and concrete do.  They are undoubtedly the cheapest, that’s why they are so popular, but this as with so many eco-choices, comes down to your choice of how far you are prepared to go.

It might not be possible to use some of the more unusual eco-friendly materials such as straw bales or rammed earth, if you will not be able to blend them into your house, although planners are getting more used to seeing these options and are less likely to turn them down these days.  Wooden frames are a more acceptable option; they act as carbon dioxide stores and are renewable, as long as you ensure that the wood is obtained from a reputable source.

A large exposed wooden frame using green oak timbers and construction techniques similar to those used for mediaeval barns can give a wonderful cathedral-like atmosphere.  Or, if that’s not going to blend in with your home, the frame can be concealed behind boards or plaster and no one would know it wasn’t an ordinary brick-built extension.

Generating Power

Eco friendly features such as solar panels, wind turbines and grey water systems are increasingly being incorporated into new housing projects.  With some local authorities requiring say 10% of renewable energy as a condition of planning permission. 

It is often easier when building new to install mechanisms to generate power,  rather than retro-fit.  Solar heating panels can be put on a roof and linked into a heating system to provide hot water, or photovoltaic (PV) cells can provide electricity and stored in batteries on site or surplus electricity sold back to the grid.
 
It is possible to buy PV cells in the same form as traditional roofing tiles, for a concealed appearance and more acceptable to planners if you are in an area that is subject to restrictions.   Wind turbines can be installed but are unlikely to deliver any real gains unless you are in a very windy area or can get permission to mount the turbine on a high mast, where the wind speeds are greater.

Ground Source/ Air Source Heat Pumps

Ground-source heat is extracted from the low-temperature heat (10–20°C) that is found at relatively shallow depths within the earth’s crust. This source of heat remains at a relatively constant temperature all year and can be taken from the ground itself or from groundwater. Heat pumps can increase the temperature to provide a more useful output temperature of around 40–50°C, ideal for low-temperature heating systems like under floor systems and radiant panels. Air source heat pumps are less efficient and are situated above ground.

Solar

Solar energy involves capturing and harnessing the sun’s energy. There are three main ways of doing this: 

• Passive solar design ensures that a building’s form and fabric captures the sun’s energy and reduces the need for artificial light and heating
• Active solar water heating converts solar radiation into heat, which can be used directly or stored
• Solar photovoltaic (PV) panels or solar cells convert sunlight into electricity

Microgeneration

Micropower, or Microgeneration is the production of energy on the smallest of scales, for individual buildings or communities. Micropower technologies emit low amounts of carbon dioxide(CO2), or in some cases, no carbon dioxide at all, whilst allowing consumers to generate their own heat and/or electricity.

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Microgeneration comes in various forms. There are two categories of solar powered technologies; photovoltaic (PV) systems, that produce electricity, and solar thermal systems to provide hot-water and sometimes space heating. Ground Source Heat Pumps use energy stored in the ground for space heating and micro-Combined Heat and Power (micro-CHP) look and operate similar to gas boilers whilst providing electricity as well as heat. Micro turbines provide electricity, either powered by the wind or naturally flowing water and the latest development is the roof or wall mounted wind turbine. Hydrogen powered fuel cells to provide heat and electricity at the commercial level are currently being developed and are expected to emerge in the next few years. 

• Microgeneration is cost-effective. Some of Micropower technologies are more accessible than others but all can deliver on at least two of the four energy policy objectives; reductions in CO2 emissions, reliability of supply, fuel poverty relief and maintaining competitiveness. For example, a micro-CHP unit will deliver the same comfort levels as a modern boiler, whilst reducing the emissions of a typical house by 1.5 tonnes (around 25%) of CO2 per year. This can help relieve fuel poverty, supply 1 - 5kW of peak electricity generating capacity - and provide the major utilities with some competition. Other forms, such as micro-wind turbines and solar panels, can cut energy bills by up to 100 pounds per year or be integrated in conjunction with other types of microgenerators to offer genuine zero carbon residences. 

• A typical large power station wastes over a third of its fuel by simply heating up the atmosphere. A further 10% of this is wasted in transmission and distribution, meaning less than half of the fuel is used productively by the consumer. By comparison, microgeneration technologies use more than 90% of the fuel productively for heat or electricity, or are powered by clean, renewable sources.
   
• Microgeneration helps to combat climate change. Some forms of micropower use fuels or energy sources that produce no greenhouse gases and are classed as renewable energy. Those that do use fossil fuels do so with efficiencies typically of greater than 90%.
   
• Some micropower technologies, when taken up in large numbers, will provide a more predictable source of power generation than large power stations. They also relieve pressure on the grid at times of strain. They enhance diversity and security of supply, and for some technologies back-up power is also available in the event of a blackout.
   
• Microgeneration is a catalyst for cultural change.There are wider benefits than just cost and carbon reductions Consumers with microgeneration exhibit noticeable changes in their energy use, as well as sending a clear visual signal of a property contributes in generating low or zero carbon energy to neighbours.

The British Wind Energy Association (BWEA) identified significant annual growth in the number of small wind turbines being installed, with an 80% increase confirming the UK as 'the world leader in small systems technology'. 

Whilst commercial scale wind farm developments can generate significant returns for the landowner providing the land, a well sited small turbine can offer a landowner or individual householder not only savings on their electricity bills, but also an opportunity to export surplus energy to the grid.

Hydro Electrical Power 

We have used running water as an energy source for thousands of years, mainly to grind corn. The first house in the world to be lit by hydroelectricity was Cragside House in Northumberland in 1878.  In 1882 on the Fox river, in the USA, hydroelectricity produced enough power to light two paper mills and a house. 

Nowadays there are many hydro-electric power stations, providing around 20% of the world's electricity. The name comes from "hydro", the Greek word for water.

When it was first built, the huge "Hoover Dam", on the Colorado river,  supplied much of the electricity for the city of Las Vegas; however now Las Vegas has grown so much, the city gets most of its energy from other sources.

Although there are many suitable sites around the world, hydro-electric dams are very expensive to build. However, once the station is built, the water comes free of charge, and there is no waste or pollution.

If your property has a location close to a suitable water supply, it may be that a small scale hydro scheme could be a practical and economic project that could provide power for a single residence or community. Technological advances in turbine efficiency mean that even locations with relatively small flows can generate electricity efficiently.

Biomass

Biomass is biological material derived from living, or recently living organisms. In the context of biomass for energy this is often used to mean plant based material, but biomass can equally apply to both animal and vegetable derived material.  

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Biomass is carbon based and is composed of a mixture of organic molecules containing hydrogen, usually including atoms of oxygen, often nitrogen and also small quantities of other atoms, including alkali, alkaline earth and heavy metals.  These metals are often found in functional molecules such as the porphyrins which include chlorophyll which contains magnesium.

The carbon used to construct biomass is absorbed from the atmosphere as carbon dioxide (CO2) by plant life, using energy from the sun. Plants may subsequently be eaten by animals and thus converted into animal biomass. However the primary absorption is performed by plants. If plant material is not eaten it is generally either broken down by microrganisms or burned:

• If broken down it releases the carbon back to the atmosphere, mainly as either carbon dioxide (CO2) or methane (CH4), depending upon the conditions and processes involved.
• If burned the carbon is returned to the atmosphere as CO2.

These processes have happened for as long as there have been plants on Earth and is part of what is known as the carbon cycle.

Fossil fuels such as coal, oil and gas are also derived from biological material, however material that absorbed CO2 from the atmosphere many millions of years ago.

As fuels they offer high energy density, but making use of that energy involves burning the fuel, with the oxidation of the carbon to carbon dioxide and the hydrogen to water (vapour).  Unless they are captured and stored, these combustion products are usually released to the atmosphere, returning carbon sequestered millions of years ago and thus contributing to increased atmospheric concentrations.

The vital difference between biomass and fossil fuels is one of time scale.

Biomass takes carbon out of the atmosphere while it is growing, and returns it as it is burned.  If it is managed on a sustainable basis, biomass is harvested as part of a constantly replenished crop. This is either during woodland or arboricultural management or coppicing or as part of a continuous programme of replanting with the new growth taking up CO2 from the atmosphere at the same time as it is released by combustion of the previous harvest.  This maintains a closed carbon cycle with no net increase in atmospheric CO2 levels.

Categories of biomass materials

Within this definition, biomass for energy can include a wide range of materials.

The realities of the economics mean that high value material for which there is an alternative market, such as good quality, large timber, are very unlikely to become available for energy applications.  However there are huge resources of residues, co-products and waste that exist in the UK which could potentially become available, in quantity, at relatively low cost, or even negative cost where there is currently a requirement to pay for disposal.

There are five basic categories of material:

• Virgin wood, from forestry, arboricultural activities or from wood processing
• Energy crops: high yield crops grown specifically for energy applications
• Agricultural residues: residues from agriculture harvesting or processing
• Food waste, from food and drink manufacture, preparation and processing, and post-consumer waste

Industrial waste and co-products from manufacturing and industrial processes. 

More and more owners of farms and estates are looking at alternative sources of energy to reduce their fuel and electricity costs as well as their carbon footprint. 

Biomass heating can be a solution to replace existing oil, electric or gas heating systems on houses, offices, commercial units and grain storage. The principal sources of biomass for fuel include specially grown energy crops, and biodegradable waste.

There are clear benefits in a biomass heating system - a reduction in running costs by up to 80%, self sufficiency of fuel supply and a reduced impact on the environment.

Anaerobic Digestion 

One of the most sustainable and economically viable sources of renewable energy is Anaerobic Digestion (AD). 

Anaerobic Digestion (AD) is a biological process that happens naturally when bacteria breaks down organic matter in environments with little or no oxygen. It is effectively a controlled and enclosed version of the anaerobic breakdown of organic waste in landfill which releases methane. 

Almost any organic material can be processed with AD, including waste paper and cardboard (which is of too low a grade to recycle, e.g. because of food contamination), grass clippings, leftover food, industrial effluents, sewage and animal waste. 

Energy  

AD produces a biogas made up of around 60 per cent methane and 40 per cent carbon dioxide (CO2). This can be burnt to generate heat or electricity or can be used as a vehicle fuel. If used to generate electricity the biogas needs to be scrubbed. It can then power the AD process or be added to the national grid and heat for homes.

Digestate 

As well as biogas, AD produces a solid and liquid residue called digestate which can be used as a soil conditioner to fertilise land. The amount of biogas and the quality of digestates obtained will vary according to the feedstock used. More gas will be produced if the feedstock is putrescible, which means it is more liable to decompose. Sewage and manure yield less biogas as the animal which produced it has already taken out some of the energy content. 

Applications  

In the UK, AD has until recently been limited to small on-farm digesters. However AD is widely used across Europe. Denmark has a number of farm co-operative AD plants which produce electricity and district heating for local villages, biogas plants have been built in Sweden to produce vehicle fuel for fleets of town buses and Germany and Austria have several thousand on-farm digesters treating mixtures of manure, energy crops and restaurant waste, with the biogas used to produce electricity.

AD is also widespread in other parts of the world. India and Thailand have several thousand mostly small scale plants. In developing countries, simple home and farm-based AD systems offer the potential for cheap, low cost energy from biogas. 

When treating municipal waste, AD can be used to process specific source separated waste streams such as separately collected food waste. The digestate will be uncontaminated so can be used as a soil improver. To minimise the impact our waste has on the climate, Friends of the Earth believes that compostable and recyclable material should be separated at source for treatment or reprocessing, using AD where suitable.

Mechanical biological treatment 

AD can also be combined with mechanical sorting systems to process residual mixed municipal waste (mechanical biological treatment or MBT). After recyclable and compostable materials have been separated from the waste stream, MBT is the best way to treat the remaining waste in terms of the environment, and in particular climate change.

In an MBT facility, the waste goes through two processes, though the order can vary:

1. machinery is used to mechanically remove any remaining recyclable waste still left in the waste stream (e.g. metals, plastics, glass)

2. the waste is composted or anaerobically digested. This reduces the volume of waste and makes it biologically inactive so it can be landfilled without releasing methane.
 There has never been a better time to consider setting up an AD plant.

• Central Government is encouraging AD through the Renewable Obligation initiative and capital grant funding
• It provides the only viable alternative to the disposal of biodegradable waste in landfill
• It provides a solution for livestock farmers to comply with the new NVZ regulations and earn additional income
• Farmers can become self sufficient in heat and electricity
• It is a highly sustainable and economically viable diversification opportunity

There are many different types of AD technology available ranging from wet to dry systems and a combination of the two. It is essential that the correct system is chosen to deal with the fuel source that will be feeding the plant. They range from simple wet systems taking in animal slurries with relatively low gas yields to sophisticated wet and dry systems taking in catering waste from food processors, green municipal waste or indeed abattoir waste.
 
The Government is actively encouraging investment in AD plants for a variety of reasons including the need to significantly reduce the amount of biodegradable waste dumped in landfill to reduce greenhouse gas emissions and to provide an alternative source of home generated household gas and electricity.
 
The incentives on offer include a double ROC for electricity generated through bio-methane, climate change levy, increased landfill gate fees and tax, enhanced capital allowances and generous capital grant schemes.
Farmers have never been better placed to exploit an emerging technology that not only solves a significant waste problem but also has the potential to generate significant income.

Establishing an AD unit can be an extremely profitable form of diversification but professional advice should be sought at the outset to ensure that the high level of investment is made in technology that is well proven reliable and is able to digest a wide range of fuel types if one source of fuel becomes scarce. 

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