[16469] Low Energy Building Design Critique 2 Adam Boney, Fraser Cassels, Marc Breslin and Nick Burns

Our Design 1st Floor

Construction method: Timber Framing Required minimal energy to process material Carbon neutral material Allows a greater thickness for external walls therefore significantly greater U values Can be sourced from local companies on the Shetland island

Insulation : 2 possibilities U value target : 0.1 – 0.15 W/m K Cellulose Insulation: Sustainable and low embodied energy 80% recycled paper 20% less energy to manufacture than other fibres Thermal conductivity 0.035 – 0.04 W/m K Sheep’s Wool: Sustainable material which can be locally provided 14% of the energy used to manufacture glass fibre Thermal conductivity 0.04 w / m K

Draught proofing and thermal envelope External door and garage are excluded from the thermal envelope. Insulation installed below the concrete floor slab Wall insulation continues down to bottom of concrete slab to prevent thermal bridging Gaps filled with foam sealants Diagram above shows main sources of draughts.

Doors and Windows High performance door threshold seals installed which seal air gaps reducing draughts and prevent water entering the building Door draught extruders fitted to other side also Windows are one of the weakest points thermally in building envelope Install high performance triple glazed windows Low emissivity glass U value 0.6 W/m Provide wooden window frames giving a U value of 0.16 W /mK to reduce thermal bridging

Lighting Day lighting: Reduces the amount of artificial light need Benefits of natural day light Increase performance Reducing in energy cost The disadvantages the natural light it our design Window size Glare Heat loss

Lighting Brightness Same brightness Less wattage (about 1/3) Costing CFL Bulb Standard Bulb 14 watts 40 watts Brightness Same brightness Less wattage (about 1/3) Costing More expensive Last longer LED Bulb Standard Bulb 4.2 watts 40 watts Brightness Same brightness Less wattage (about 1/10) Cool lighting reducing energy consumption

Wind Power Shetland wind power- supply renewable energy Turbines produced by 3 main manufacturers Westwind Turbines Proven Turbines Evance Turbine

Wind Power Opting for a stand alone turbine: Carry out comparison Assess best supplier and turbine Power calculation spreadsheet P=0.5ρAV³ - www.REUK.co.uk

Wind Power- Small turbine Speed Power Area

Wind power- Large turbine Speed Power Area

Water Average household water use is difficult to pin down Average annual levels of consumption (m3): Average use = 182,000L/year http://www.ccwater.org.uk/server.php?show=ConWebDoc.913

Technologies 1. Rainwater harvesting: Plenty of rain in Unst- average rainfall/year is 1,220mm1 Systems can provide 100% of water demand, however this is rarely done 1. http://www.shetland.gov.uk/council/documents/18170-Shet-in-Statistics.pdf

Technologies Rainwater harvesting: Variability within system design and details Model agreements for sustainable water systems; CIRIA, 2004

Collection Initial thoughts on collection area focused on roof However, collection area can be expanded to other parts of the house as well- driveways/pavements, for example

Filtration Water for different uses requires different levels of filtration We thought it best to have one filtration system for the whole system Sediment pre-filtration Carbon or multimedia fibre UV sterilization

Storage Underground Above ground

Heating Passivhaus requires consumption for electricity, heating and hot water be < 120kW/m2/year Typically, solar thermal panel is used to provide heat for some of hot water needs- not an option for Unst An inline water heater could be used

Design calculations Roof area = Width x Length of roof = 152.29m2 http://www.rainharvesting.co.uk/pages/design/dsgn4.html Roof area = Width x Length of roof = 152.29m2 Run-off coefficient = 0.75 for pitched roof Filter efficiency = 85% (A conservative estimate- example calculations typically gave efficiency as 90+%) Rainwater yield (Litres/year) = Roof area (m2) x Annual rainfall (mm) x Run-off coefficient x Filter efficiency Rainwater yield = 118,443L/year -not enough

Possible solutions… Grey water harvesting Sea water

The next steps of design Complete the day lighting calculations and install low energy bulbs into the DiaLUX software PV cells result Confirm the water manage design Finalise the energy systems calculations which are incorporated within the design Work on the MVHR system for the building. Finalise Electrical consumption Choose turbine & manufacturer.