1. [16469] Low Energy Building Design
Critique 2
Adam Boney, Fraser Cassels, Marc Breslin and Nick Burns

2. Our Design
1st Floor

3. 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

4. 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 – 0.04 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

5. 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.

6. 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

7. 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

8. 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

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

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

11. Wind Power- Small turbine
Speed
Power
Area

12. Wind power- Large turbine
Speed
Power
Area

13. Water Average household water use is difficult to pin down
Average annual levels of consumption (m3):
Average use = 182,000L/year

14. 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.

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

16. 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

17. 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

18. Storage
Underground Above ground

19. 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

20. Design calculations Roof area = Width x Length of roof = 152.29m2
Roof area = Width x Length of roof = m2
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

21. Possible solutions…
Grey water harvesting
Sea water

22. 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.