Go green with your new build
We can eclipse today’s past mistakes and invest in the promise, peace and growth rates of the solar-hydrogen era and a free-energy future, rather than stealing the capital from future generations – which belongs to them. We also need to show proactive compassion and understanding to the only earth we know.
Renewable Energy – So what is it?
Renewable energy is so called because it means that the source of fuel we use can be renewed or sustained over time. Most of the world is currently dependent on fossil fuels that can never be renewed once they are consumed. Worse still, the more that are burned the more Carbon Dioxide (CO2) is released into the atmosphere. This in turn affects the ability of the ozone layer to shield us from the sun that means the earth’s temperature heats up creating erratic weather patterns.
No matter how dependent our current lifestyles are on fossil fuels we have to face up to the fact that they are already in the decline phase of production and may run out by current estimates as early as thirty years. Its no surprise then that interest in renewables has started to take off on a much larger scale since the turn of this century. No one savours the prospect of having to survive without power and live without all the useful items we have come to depend on, especially as they get older! Below are just some of the basic changes you can make today to make your house a more sustainable and earth-friendly piece of architecture.
Can I use renewable energy right now?
The good news is that sustainable technologies are already advanced enough to make sure you need never suffer hardship during your lifetime. This is why it is a very exciting area for those of us who not only want to build our own homes but build them so that they run as economically as possible. At the least it can currently help cut our utilities bills, but better still, the more people that adopt these sources the less pollution we release into the atmosphere !
We have kept the descriptions of the sustainable technologies that utilise renewable energy as simple as possible just so that anyone interested can easily understand how each one works and what might be right for them if they want to integrate renewable energy sources with sustainable building techniques in their self-build project.
The Main Types of Renewable Energy
Basically there are six main renewable energy sources and sustainable technologies for exploiting them. Although news articles tend to concentrate on very large civil engineering projects like wind farms, renewable energy sources can also be harnessed by the humble self builder, provided they site their home in the right location.
Biomass is the name given to any recent organic matter that has been derived from plants as a result of the photosynthetic conversion process. Biomass energy is derived from plant and animal material, such as wood from forests, residues from agricultural and forestry processes, and industrial, human or animal wastes.
Biomass is often called ‘bio-energy’ or ‘bio-fuels’. These bio-fuels are produced from organic materials, either directly from plants or indirectly from industrial, commercial, domestic or agricultural products. Bio-fuels fall into two main categories:
Woody biomass includes – forest products, untreated wood products, energy crops, short rotation coppice (SRC) e.g. willow, miscanthus (elephant grass).
Non-woody biomass includes – animal wastes, industrial and biodegradable municipal products from food processing and high-energy crops e.g. rape, sugar cane, maize. SRC and high energy crops are sometimes referred to under the more general term of ‘energy crops’ i.e. crops that are grown specifically for energy.
These sources of biomass are then converted into usable heat, electricity or motive power using a range of conversion processes. These include combustion, gasification, pyrolysis, anaerobic digestion, fermentation and mechanical processing. During the conversion processes when energy is released, often in the form of heat, the carbon is re-oxidised to CO2 to replace that which was absorbed while the plant was growing.
Ground Source Heat (GSH)
The earth, a few metres below our feet, keeps a constant temperature of about 11-12C/ 55ƒF throughout the year. Because of the ground’s high thermal mass, it stores heat from the sun during the summer. Ground Source Heat Pumps (GSHP) can pump this heat from the ground into a building to provide space heating and, in some cases, pre-heating domestic hot water. For every unit of electricity used to pump the heat, 3-4 units of heat are produced.
In summer, the soil temperature is cooler than the outside air. In winter, it’s warmer. A GSH pump can use this constant temperature to heat and cool your home very efficiently. There’s no flame, no flue, no odour and no pollutants.
How does it work?
There are three important elements to a GSHP: Ground loop – comprises lengths of plastic pipe buried in the ground, either in a borehole or a straight horizontal and spiral horizontal (or ‘slinky’). Each has different characteristics allowing you to choose the most suitable for your property. The pipe is a closed circuit and is filled with a mixture of water and antifreeze, which is pumped round the pipe absorbing heat from the ground.Horizontal trenches can cost less than boreholes, but require greater land area. For slinky coil, a trench of about 10m length will provide for about 1kW of heating load.
Heat pump – although we may not know it, heat pumps are very familiar to us. Fridges and air conditioners are all examples. A heat pump works by using the evaporation and condensing of a refrigerant to move heat from one place to another. In this case, the evaporator (e.g. the squiggly loop in the cold part of your fridge) takes heat from the water in the ground loop; the condenser (the hot thing on the back of your fridge) gives up heat to a hot water tank that feeds the distribution system.
A compressor – which uses electricity, (this is what makes the noise in your fridge) moves the refrigerant around the heat pump. It also compresses the gaseous refrigerant to increase the temperature at which it condenses, to that needed for the distribution circuit.
Heat distribution system – consists of underfloor heating or radiators for space heating and water storage for hot water supply. Some systems can also be used for cooling in the summer.
In the heating season, a ground-source heat pump supplies three to four units of heat to your home for every unit of electrical energy required to operate the system. So you get two to three kilowatt hours (kWh) of free energy for every one kWh of electrical energy you pay for. In other words, a ground-source heat pump is 300% to 400% efficient.
There are several different types of Ground Source Heating configurations. The type of one you pick is dependent on the surrounding landscape your house is built in and the typical climate you experience year round.
How much will a system cost me?
The installed cost of a Ground Source Heat Pump (GSHP), for a professional installation, ranges from about £800-£1,200 per kW of peak heat output, excluding the cost of the distribution system. Trench systems tend to be at the lower end of this range. The installed cost of a typical 8kW system would therefore vary between £6,400-£9,600 plus the cost of the distribution system. Note that costs will vary and the cost for a system for your home may differ.
Micro Hydro Electric (MHE)
If you live by any source of running water: stream, river or on a boat, small water generators (micro-hydro turbines – under 100Kw) are the most reliable source of renewable energy available. One relatively small water turbine will produce power non-stop, as long as running water is available, no matter what the weather !
A small-scale hydro system usually consists of an enclosed water wheel or turbine, which is made to spin by jets of high-velocity water. The water is taken from the stream and moved down slope to the turbine through a long pipe called a penstock. Water flowing through the penstock picks up speed, and is directed at the blades of the turbine by nozzles.
The turbine spins continuously, as long as there is water to drive it. The turbine is connected to an electrical generator, and the electricity is then available for running appliances or charging batteries. The spent water is returned to the stream. This kind of system is called a “micro-hydro” system, “run-of-stream hydro” or “low-impact hydro.”
In an off-grid hydro system, electricity can be supplied directly to the loads, or via a battery bank and inverter set up. For off-grid systems, allowances should be made for any seasonal variations in water flow, which can affect the amount of electricity delivered by the system.
Turbines fall into three major styles:
- Impulse turbines
- Reaction turbines
- Submersible propeller turbines
Each is ideally suited for a different type of water supply. No matter what source of running water you have on your property, if it supplies a year-round flow of water, there is most likely a water turbine well suited to provide electricity for you.
Impulse Style Water Turbines
An impulse turbine operates on the same principle as a toy pinwheel. Water strikes the turbine runner, and pushes it in a circle. The water is delivered to the runner through a pipeline, and out a small nozzle that maximizes the force available to operate the turbine.
These types of water generator work best in sites where the water source has high head (20 feet or more). Head is the vertical distance between where the water enters the turbine system (in this case, into a pipeline) and where it reaches the turbine runner. These water turbines require minimal water flow volume, so they are ideal for sites where a relatively small amount of water runs down a fairly steep hill, as in a hillside stream or small waterfall. The most well known type of impulse turbine is the Pelton-wheel style as used in Harris Pelton turbines. But in higher flow sites, a Turgo style runner such as the one use in the Stream Engine has a higher output potential.
Reaction Style Water Turbines
Reaction turbines require a much larger amount of water flow than impulse styles, but can operate with as little as two feet of head, making them ideal for sites where there may be relatively flat land, but a large water flow.
These route water either through a pipeline into an enclosed housing, or through a canal to an open flume, (note: most open-flume designs can be modified to use a pipeline and enclosed housing if it better suits your installation site). The turbine runner is immersed in the water, which exits the housing through the turbine, turning the alternator as it ‘drops’ through the runner blades. No matter which runner style a reaction turbine uses, a specially designed outlet tube increases the turbine power output by creating suction as the water exits the system.
Submersible Propeller Water Turbines
These turbines are the least efficient of the three styles, but also the simplest design. A propeller mounted on the front of the turbine is attached to an alternator inside the main turbine housing. When submerged in a fast moving water source, the force of the passing water rotates the propeller. Propeller style generators work well for locations with a fast moving, relatively deep stream or river, where a water diversion system is not possible, or when mounted on a moving boat.
For people with a good source of year-round running water, one or two water turbines may be all they need to power their homes. However, for those with seasonal, winter-only streams available, a small water generator may be the perfect back up for a solar system’s off-peak season.
Hydro costs are very site specific. For low head systems (not including the civil works – so assuming there was an existing pond or weir), costs may be in the region of £4,000 per kW installed up to about 10kW, and would drop per kW for larger schemes. These schemes are generally more expensive as they require bigger turbines and more civil works.
For medium heads, a fixed cost of about £10,000, and then about £2,500 per kW up to around 10kW – so a typical 5kW domestic scheme might cost £20-£25,000. Unit costs drop for larger schemes.Contact us today for a free consultation and quote
Energy from the sun has been harnessed for thousands of years.
We utilise this energy in three main ways:
Passive heat: This is the heat that we receive from the sun naturally. This can be taken into account in the design of buildings so that less additional heating is required.
Solar thermal: Where we use the sun’s heat to provide hot water for homes or swimming pools.
Photovoltaics: Uses energy from the sun to create electricity to run appliances and lighting.
When talking about solar energy it is important to distinguish between these three types.
Requires only daylight – not direct sunlight – to generate electricity. PV systems use cells to convert solar radiation into electricity. The PV cell consists of one or two layers of a semi-conducting material, usually silicon. When light shines on the cell it creates an electric field across the layers, causing electricity to flow. The greater the intensity of the light, the greater the flow of electricity.
PV systems generate no greenhouse gases, saving approximately 450kg of carbon dioxide per year for each kWp installed.
The three main types of solar cells are:
- Mono-crystalline: made from thin slices cut from a single crystal of silicon. This has a typical efficiency of 15%.
- Poly-crystalline: made from thin slices cut from a block of silicon crystals. This has a typical efficiency of at least 13%.
- Thin Film: made from a very thin layer of semiconductor atoms deposited on a glass or metal base. This has a typical efficiency of 7%.
How do Photovoltaic (PV) cells work
Individual PV cells are connected together to form a module. Modules are then linked and sized to meet a particular load (need). We call this the PV array. A PV array fitted on a building can be connected to the local electricity supply network. Thus, any excess electricity produced can be exported to the grid. Alternatively, when demand is high, extra electricity can be purchased from the grid through the utility companies.
Where there is no mains supply, PV arrays can be used to charge batteries. PV arrays now come in a variety of shapes and colours, ranging from grey ‘solar tiles’ that look like roof tiles, to panels and transparent cells that you can use on conservatories and glass to provide shading as well as generating electricity.
The size of a PV array required to provide electricity for a typical home varies, depending on load requirements (what you want it to power) and the type of cell used. Typical systems are generally around 1.5kWp, enough to provide around a third of the average family’s annual supply (assuming gas is used for heating requirements and there are no energy efficiency savings). This array would typically cover 10-15m2 of roof area.
Solar Water Heaters (SWH)
Solar water heating systems gather energy radiated by the sun and convert it into useful heat in the form of hot water. They work alongside your conventional water heater to ensure year round hot water.Provide almost all of your hot water during the summer months and about 50% year round. Reduce your carbon dioxide emissions by 0.25-0.5 tonne per year, depending on the fuel replaced.
How they work
A solar water heating system for domestic hot water comprises three main components: solar panels; hot water cylinder; and a plumbing system.
- Solar panels are fitted to your roof and contain collectors. The collectors absorb and retain heat from the suns rays and transfer this heat to a fluid.
- A hot water cylinder stores the hot water that is heated during the day and supplies it for use later.
- The plumbing system is made up of simple piping and sometimes a pump, which moves the heated fluid around the system and through the hot water cylinder.
Different solar power systems
There is a range of different system types and configurations for solar hot water systems. Some models use a small photovoltaic panel to power their circulating pump. Others use natural thermo siphon to circulate the water through the panel, thereby eliminating the need for ANY power source.
For areas that are liable to periods of freezing temperatures, a closed loop system is used, whereby an intermediary (anti-freeze) fluid and a heat exchange system heat the water in the tank indirectly. Other systems circulate and heat the water directly in the panels.
The system which best suits your needs depends on a range of factors, including:
- Amount of south facing roof space.
- Existing water heating system (e.g. some combi-boilers may not be suitable).
- Your budget.
Cost and maintenance
Prices for installed systems average between £2,500-£4,000. Costs vary due to factors such as size of collector, type of roof, type of existing hot water system and geographic location. Alternatively you can fit or build the system yourself. It can work out cheaper (around £500-£1,500) but will take longer and youíll need a certain level of skill. You can get training and support from your local solar club.
Various organisations throughout the UK provide funding support for the installation of solar thermal systems. Solar hot water systems generally come with a 10-year warranty and require very little maintenance. A yearly check by the householder and a more detailed check every 3-5 years should be sufficient (although you should consult your system supplier for exact maintenance requirements).
Usual requirements are:
- Preferably 2-4m2 of southeast to southwest facing roof space that receives minimal shading during the main part of day, to locate the panels.
- Space to locate an additional water cylinder if required, or a change to your existing one depending on the solar system.
Wind energy resources
In the UK we have a large potential wind resource. Although we have 40% of Europe’s total wind energy resource, it remains largely untapped, currently meeting only 0.5% of our electricity requirements. This is expected to increase to at least 5% by 2010.
Small variations in wind speed can result in large changes in potential energy output. For example, turbines at a site with an average wind speed of 8 metres per second (m/s) should produce 80% more electricity than the same turbines on a site where the average wind speed is 6m/s.
Individual turbines vary in size and power output from a few hundred watts to 2-3 megawatts (as a guide, an electrical kettle uses approximately 1,000 watts or 1 kilowatt).
Wind speed also increases with height. So it is best to have the turbine high on a mast or tower. The ideal siting is a smooth-top hill with a flat, clear exposure, free from excessive turbulence and local obstructions such as large trees, houses or other buildings. Knowledge of the local wind resource is critical to designing a wind energy system and predicting output. Where output is less critical, Meteorological Office data, other monitoring or even local knowledge could be used.
For people who need to bring power lines into their property an independent system could have a lower cost. It depends on how much power you need and how far away the power lines are.The technologies of wind, solar, storage, and power conversion have matured greatly over the last twenty years. It is now quite reasonable, and common, to use wind and solar to provide electricity to areas not served by the power grid. For an independent, off-grid, power system the efficiency of your lights and appliances is extremely important. You should use the most efficient equipment you can find.
Wind and solar are intermittent resources, so some short-term storage is required to deliver reliable 24-hour ìgrid-gradeî power. Back-up engine generators (gas, propane, or diesel) are necessary for larger systems. Off-grid power systems for a home typically cost from $5,000 to $70,000.
Combining two generating technologies, like wind and diesel, creates a hybrid system. Wind and solar are often combined in a hybrid system because they reinforce each other on a daily and seasonal basis. The wind often blows when the sun is not shining (night, storms, winter, etc.). The sun often shines during periods with low wind (summer, wind lulls due to high-pressure systems, etc.).
London Elite Trades can design a remote power system, calculate its performance and economics – we have experience in all areas of the installation and the maintenance of wind and solar energy systems.
The Great Housing Problem
There are currently about 400,000,000 people homeless on Earth. Current projections say another 400,000,000 by around the year 2030. That means that if we started today, producing 10,000,000 houses per year, (That’s 27,397 houses per day, also working on Christmas!) then we won’t hold even. It would take 40 years to house today’s 400,000,000 homeless at that rate, and we’ll have replaced them in less time than that!
Not everyone is going to want, or be able to afford, the same kind of house. There are already designs available for everything from “disaster/war victim who’s just had their entire world destroyed around them” to “just graduated from college, looking to get a first home and start a family” to “established professional, looking to escape the suburbs and live in comfort on some large plot of land they just bought.”
It’s more important to provide the appropriate technology for people, so they can move up their own personal standard-of-living ladder. So someone who has no house would probably appreciate even a cardboard or Corrugate dome shelter. Professionals from the city will not be tempted by a cardboard dome.
However, something with 2-4 times the floor space, at 1/5-1/10th the cost of a standard house, and more privacy than they’ve ever had in a city, no utility bills, their own garden, great views, and still in touch with the communications net…that might be interesting to them.
Looking forward with Autonomous Housing
Rather than designing everything around a centralised system, with central power plants, water-treatment plants, sewer systems, gas lines, phone lines, TV cable, and the attendant spider web of wires and pipes that those use.
One could instead build a self-contained house, which allows one to cut free of the various umbilical cords of current society, and live anywhere on this planet’s land surface. Eventually, also the sea surface, under the sea, and then the Moon, Mars, and elsewhere, but that’s projecting far into the future!
The basic design must possess a strong shell that shelters you from the elements, insulated walls, solar & wind power, along with fuel cells, methane-digesters hooked up to composting toilets, water-reprocessing facilities in the house, a hydroponic greenhouse, wireless communications, etc. It catches rainwater, and/or pumps & purifies from nearby lakes, streams, & rivers, or even condenses water directly from the atmosphere.
It’s meant to help you survive in the various extremes of this planet. it could even be a stationary base-camp, which can be picked up by helicopter and delivered to any GPS coordinates required.
This idea still presents one problem though;
- How do you get rid of the need for roads?
- We can make self-contained power systems, and water, food, communication, etc. but what about getting to & fro?
- What about going to work?
- What about driving to town for some supplies?
Besides the transport problem, autonomous housing stacks up really well in a cost/benefit analysis.Contact London Elite Trades for a Free Consultation Today!