Energy in use. Energy is typically used in homes to: heat rooms heat water cook power electrical appliances & lights

Transcription

1 Energy in use Energy in use is the energy used everyday once the building is occupied. Space heating 60% Energy is typically used in homes to: Hot water 25% Electricity 10% Cooking 7% Most energy, 60%, is used for space heating. heat rooms heat water cook power electrical appliances & lights

2 Where does energy come from? 50% Energy to run buildings uses huge amounts of fuel. Buildings are responsible for 50% of Europe's energy use and housing produces 25 % of the UK s carbon emissions. oil gas ENERGY coal heat, light & appliances We get our energy from primary sources (e.g. crude oil) which is converted (e.g. into electricity) for use in our buildings. renewable e.g. wind, solar

3 Choose your supply carefully Different energy sources result in very different CO 2 emissions: Source:

4 How can we reduce energy use? As designers, we want to: minimise demand for energy; maximise the energy used from sustainable sources; and minimise the amount we waste. Typical sources of heat loss from a house. The Passiv Haus uses only passive energy gained from the sun, from occupants body heat and incidental heat radiating from household appliances. Key design features include good orientation, large areas of glazing, good draught proofing and high levels of insulation.

5 Energy use depends on the user Building occupants are critical to effective reduction in energy use. What will help to make people become more efficient users? How many times do you leave the light on, leave the door open or TV on standby? What would persuade you to change your behaviour? Can you design a guide for your building users to maximise positive impacts on the environment? Explore some of the myths about energy use at See User Behaviour in Energy Efficient Homes %20Phase%202%20report%20v1.0.pdf

6 Don t waste it insulate it It is a law of physics that heat will flow in a solid, liquid or gas or between them until the temperature of each is equal. If it is cold outside then the warmth (energy) will try to escape from a house until it is the same temperature as the ambient air temperature outside. Insulation acts as a barrier to that heat flow. The bigger the difference in temperature, the faster the rate of flow of heat. Heat flows in a house In summer we may want to stop heat getting into a house which may suggest different design features and materials. How can we stop heat flow? Heat flows through different materials at different rates some materials are better heat conductors than others. The denser the material, the better it is for conducting heat, allowing heat to flow through it more quickly. Bad heat conductors, e.g. wool, are therefore good insulators. Cork insulation Rockwool insulation

7 What s best? Good insulation can be achieved by materials: that have a low density; incorporate air pockets; such as polyurethane (oil derivative), expanded polystyrene, sheep s wool, recycled paper; that provide any insulation it s always better than none! Warmcel insulation made from recycled newspaper Sheep s wool insulation

8 It s a matter of calculation Heat transfer happens in 3 ways: conduction; convection; radiation. When heat passes out of a building all three methods of transference are at work. For example, heat is conducted through solid parts of a wall, radiated across cavities and from the outside surface, and is also convected from the outside surface by wind passing across that surface. Definition of U-value: heat flow (Watts) through 1m 2 of a construction at 1 degree C temperature difference between the inside & the outside. A measure, called the U-value, combines the impact of all three methods of heat transfer on the material or structure concerned. There are standard tables and manufacturers specification for most materials. The impact of combining different materials and building designs can be calculated. Golden rule: the lower U-value, the better the insulation.

9 Achieving a balance Draughts result in heat loss and are therefore unwelcome, but adequate ventilation is essential. Ventilation is critical in achieving a feeling of freshness and comfort. Fumes, smells, humidity and excess heat all call for natural or mechanical ventilation, depending on the situation. Ventilation requirements are calculated in metres cubed per person per hour, or air changes per hour. Designing buildings so that they have very few draughts can save a lot of energy by reducing the heat lost. Effective draught exclusion depends on good detailing of doors and windows. At Bed Zed, the hoods on the roof move around with the wind creating a draft up the chimney providing suction to let warm moist air out. Instead of using air conditioning, employing a huge amount of energy, we can use the natural stack effect to ventilate buildings. Warm air rises naturally, it simply needs a path to follow. If the air is just let out, it will take all the heat with it. A heat recovery system can stop this heat loss, by letting the heat from the air out transfer to the air coming in..

10 Reducing energy use by design Steps to minimise energy use and provide a healthy built environment: minimise heat losses by insulating the building fabric; provide good levels of ventilation to assure air quality; minimise demand by using energy efficient lightbulbs and A rated appliances, think about external lighting too; design space for clothes drying to reduce use of tumble driers; install combined heat and power and/or use renewable energy sources to heat space and water. simple building plans (shape) result in less heat loss than complex shapes; ensure ample daylight provides natural internal lighting; consider the location in terms of access to facilities & transport make best use of natural features of the site, sheltered situations can reduce heat losses by as much as 20%; orient the building and design areas of glazing to maximise solar gain in winter and shade in summer; Follow this link for more in depth consideration of land use, siting & orientation.

11 No energy How important is access to energy for human development? 2 BILLION people worldwide don t have access to grid electricity or commercial energy supply Practical Action, a development organisation, is working to improve poor people s access to energy They also work to help people use the energy sources they can access more efficiently and click on energy

12 Practical Action s projects Practical Action s projects provide energy to light homes energy to light schools and hospitals energy to run small scale businesses Practical Action promotes micro-hydro systems biogas plants wind power systems and click on energy

13 Harnessing the wind in Sri Lanka More than 70% of Sri Lankans live in rural areas where there is no grid electricity Weerasinghe, pictured, had to use kerosene and an old car battery Kerosene lamps were used for lighting and are notorious for causing burns The battery cost more than eight dollars a day, a fortune to him He can now generate light from his own wind turbine. He says, It s wonderful. Straight away there was enough power to light a few light bulbs. Now I can work longer and my children can do their homework. Is a wind turbine a possibility in your design? go to energy, wind power

14 Improved cooking stoves Traditional cooking methods use a three stone fire, which wastes much heat and wood Anagi stoves, shown below right, have helped cut down use of firewood by one third They also improve the efficiency, enabling two or three utensils to be used from the same fire They are cheap to make, use local clays, and cut down risks of burns. Have you chosen to use energy efficient methods? go to energy, improved stoves

15 In summary, wherever in the world

16 Further resources There are links to other information throughout this presentation look for the house symbol to go to presentations that consider the issues in more depth. There are lots of web-based resources, some of which focus on energy issues in building. They include: