Energy Conservation In Buildings

• building design • use of materials/construction methods with low embodied energy • use of materials with low thermal conductivity/transmittance (insulation) • energy management tech • low energy appliances • human behaviour

35% walls 25% roof/attic 25% windows/doors 15% floor

design + material choice = low energy losses • use of tech can ensure that a building and its appliances are energy efficient • changing human behaviours will also lead to further energy conservation • must be supplied with energy rating, as with all household white good appliances

• temp gradient between inside and outside • thermal conductivity/resistance of construction materials that form external walls/roof/windows • loss of warm air from inside the building • chilling effect caused by wind and rain

• reducing temp gradient • increasing thermal conductivity and therefore reducing the amount of warm air lost from inside aka INSULATING

BIGGEST = space heating 45% water heating 18% space cooling 9% computers and electronics 6% lights 6% fridge 4%

Orientation Surface area Choice of materials

• where highest energy loss = through windows, can be offset through solar gains i.e. heating rooms with sunlight • in N Hemisphere, greatest heat gains are in S facing rooms, and losses on N • the use of a room may affect the area of windows needed and room temp • the choice of position of different room types can reduce overall energy use: rooms that need to be warmer can be placed on the side with greatest passive solar gains

• shape of building plus being detached/close to surrounding buildings will impact ability to retain heat • buildings with low SA:vol ratio will lose heat less easily

• high thermal mass • low embodied energy • Earth sheltered buildings

• temp management in buildings can involve resisting periods of over-heating or low temps • materials with high thermal mass = help reduce temp extremes • high thermal mass = absorb excess heat to prevent over-heating and emit heat to reduce heating requirements e.g. concrete and water have high thermal mass

a building design strategy that uses natural energy from the sun to heat, cool, and light spaces without mechanical systems works by designing buildings to collect, store, and distribute solar energy directly from the sun, typically avoiding mechanical systems

a measure of heat loss or the overall heat transfer coefficient a lower U-value means better insulation provided by material e.g. new legislation: a new-build external wall should be about 0.25

• EXPENSIVE • pressure would mean the glass may shatter • panels need to be held apart with spacers which cannot be long, so vacuum DG is only used where there is not space for gas-filled multiple glazing • if the edge seal fails, the insulating effect fails instantly

E = U-value x area x temperature difference

• multiple layers of glass with spaces between them, reducing energy loss

• they have lower thermal conductivity and require a smaller layer gap… BUT ARE MORE EXPENSIVE

LOST: - conduction: through frame, edge spaces and sash and glazing - convection: air leakage around the frame and sash, at glazing surfaces and in the IGU space - radiation: through glazing GAIN: - radiation: solar heat gain

12-16mm

• doors: with draught excluders • windows: with curtains • radiators: shiny foil • walls: cavity insulation, plastic foam • roofs: loft insulation

a material that minimises heat flow and heat energy loss, therefore increasing efficiency of heating

• R-value (Thermal Resistance) - measures the ability of a material to resist heat flow - a higher number means better insulation - depends on material type, thickness, and density • U-Value (Thermal Transmittance) - measures the rate of heat transfer through a building element - lower U-value signifies a more effective insulator - depends on material conductivity, thickness, insulation quality, air cavities, thermal bridging, and installation

• BLANKET: wool, best for lofts and ceilings • RIGID INSULATION BOARDS: polystyrene/wood fibre, for cavity walls and floors • SPRAY FOAM INSULATION: liquid expands to fill gaps (airtight), for loft spaces and hard to reach areas • REFLECTIVE MULTIFOIL: layers of foil in roofs and walls, especially in low-space retrofits • LOOSE FILL/BLOWN IN INSULATION: cellulose, fiberglass or mineral wool, blown into attics or walls using special equipment • AEROGEL: high-tech, low density material = highest thermal performance in v thin applications. Up to 99.8% air (‘frozen smoke’)

Materials that are generally natural, plant based or recycled, that require minimal processing. They often store carbon rather than emit