Energy is typically used in homes to:

⌂ heat rooms

⌂ heat water

⌂ cook

⌂ power electrical appliances & lights

Most energy, 60%, is used for space heating.

Energy in use

Energy in use…is the energy used everyday

once the building is occupied.

Space heatin

g 60%

Electricity 10%

Cooking 7%

Hot water 25%

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

coal

renewablee.g. wind, solar

50%

ENERGY

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.

Where does energy come from?

Choose your supply carefully

Source: http://www10.antenna.nl/wise/537/gl/graph2.gif

Different energy sources result in very different CO2 emissions:

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.

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.

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 http://www.nef.org.uk/energyadvice/mythstruths.htm#answer1 See User Behaviour in Energy Efficient Homes http://www.ukace.org/research/behaviour/User%20Behaviour%20-%20Phase%202%20report%20v1.0.pdf

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.

Don’t waste it – insulate it

In summer we may want to stop heat getting into a house which may suggest different design features and materials.

Heat flows in a house

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

http://www.nef.org.uk/energyadvice/insulation.htm

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!

Sheep’s wool insulationhttp://www.sheepwoolinsulation.ie/abtprods.htm

Warmcel insulation made from recycled newspaper

Golden rule: the lower U-value , the better the insulation.

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.

It’s a matter of calculationDefinition of U-value:

heat flow (Watts) through 1m2 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.

Achieving a balance

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.

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.

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.

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.

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..

http://www.theyellowhouse.org.uk/themes/ventil.html#v1

Reducing energy use by design

⌂ 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;

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;

Follow this link for more in depth

consideration of land use, siting &

orientation.

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

www.practicalaction.org.uk and click on energy

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

www.practicalaction.org.uk and click on energy

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?

www.practicalaction.org, go to energy, wind power

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?

www.practicalaction.org, go to energy, improved stoves

In summary, wherever in the world…

www.sda-uk.org/toolsa.html

Further resourcesThere 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:www.sustainablehomes.co.uk www.bre.co.uk/services/Energy.htmlwww.dti.gov.uk/energy www.greenheat.uk.comwww.est.org.uk/bestpractice www.thecarbontrust.co.uk www.safety.odpm.gov.uk/bregs/brads.htmwww.savenergy.co.ukwww.actionenergy.org.uk