Energy Calculations
PortZED Calculation Explanation:
Residential
Generally construction to be:
- 0.1 min U value
- double glazing to sunspaces
- Triple glazing to all other areas for acoustic reasons
South facing units
- 2.5 sq m PV
- 1 wind turbine
- 1 sunspace
- 1 solar hot water panel
- A++ rated appliances
- LED lighting
- Low flow taps and showers
North facing units
- A++ rated appliances
- LED lighting
- Low flow taps and showers
- 1 wind turbine on roof
- Portion of PV on roof
- Covered clothes drying area
Wood pellet boiler in base with cycle storage area, the main duct for SVP water services and pellet flue is adjacent to lift. There is an entrance to the car park level from the road below the site and this is a one way flow system.
Electrical calculation for whole site
2 P 1 bed 24 no. @ 1900 kWh/yr 45600 kWh/yr
3 P 2 bed 26 no. @ 2200 kWh/yr 57200 kWh/yr
4 P 2 bed 24 no. @ 2400 kWh/yr 57600 kWh/yr
Total 74 units (4310 sq. m)
Live work 30-87 sq m (total 652 sq m) @ 44 kWh/m2/yr 28688 kWh/yr
Magnet showroom 492 sq m @ 57 kWh/m2/yr 28044 kWh/yr
Total electrical consumption 217132kWh/yr
Electrical production and cost (all ex VAT supply only)
VAWT ZEDFactory
78 no @ (cost + 15%) £7877.50 £614 445
One turbine per flat and one per live work (commercial linked in not dedicated)
Turbine produces 1450-1600kWh/yr each
Taking lower estimate 113 100kWh/yr
PV dedicated south units balustrading
BIPV laminate 40% higher than standard PV panels
2 no 180Wp panels 48 units @ £749 £35 952 at 808kWh/kWp
13 960kWh/yr
PV site wide to roof
Total roof area 492 sq m
340 180Wp panels approx @ £535 £181900 at 808kWh/kWp
49 450kWh/yr
PV site wide to façade
Total area 210 sq m
140 180Wp panels approx@ £535 £74900 at 808kWh/kWp
20 360kWh/yr
PV commercial linked to canopy
Total area 492 sq m
170 180Wp panels approx @ £749 (BIPV) £127330 at 808kWh/kWp
24 725kWh/yr
Energy balance 4460kWh/yr surplus
This is more than adequate to take into account cloudy years/ lower than average wind speed years
Total cost of renewables £1 034 527
Pellet store Thermal calculation
Accommodation schedule
1 live work @ 105 sq m
1 live work @ 40 sq m
4 2 bed flats 3P@ 61 sq m
4 2 bed flats 4P@ 66 sq m
4 1 bed flats 2P @ 47.5 sq m
Hot water requirement
1600kWh/annum/person
Live work assume 2P, 2 units total 6400kWh/annum
Residential 36P total 57600kWh/annum
Total hot water requirement 64 000kWh/annum
Less 8 SHW panels producing a max of 60% of 3840kWh/annum
SHW total 30 720kWh/annum
Hot water requirement (corrected) 33 280kWh/annum
Space heating requirement
3.3kWh/ sq m south facing unit
29kWh/ sq m north facing unit
Assume Live work is a south facing unit
North facing unit, area total 190 sq m
total heating 5510kWh/annum
South facing unit, area total 508 sq m
total heating 1676.4kWh/annum
Live work unit, area total 145 sq m
total heating 507.5kWh/annum
Total space heating requirement 7694kWh/annum
Total wood pellet requirement 40974 @ 85 % efficiency means 48 205 kWh/annum of delivered energy required
Pellet energy is 4600kWh/tonne so 10.48t required
Density is 1 so 10.48 cubic m required per annum
This can be approximated to 1 10 tonne delivery truck per year with a top up delivery mid season
If the tank is within the width of the construction then the pellet wall would be 4.5 m high, 500mm thick (wall thickness), 4.5 m high (auger at 500mm above FFL makes overall height 5m)
Across the whole site 58 no evacuated solar hot water tubes. This will cost (supply only)
£440 x 58no £25 520 (ex VAT) but does not include cylinder, controls and associated pipework
The thermal store and boiler size for the block will have to be sized by a sub consultant/ M&E engineer
Shoreham, Energy Calculations, commentary on calculation
Basis
Each unit from BedZED figures can be seen to have an electrical load quoted in kWh/annum.
Space heating is a function of the ZED construction specification but also the orientation. The space heating of a northern unit is larger than that from a southern unit which receives passive solar heating.
Renewable devices can take a number of forms
Electrical:
- vertical axis wind turbines
- Photo voltaic panels
Hot water:
- A solar hot water panel for each south facing residential units
- Wood pellet boiler per tower for hot water and heating
North facing are be minimized as they have:
- Limited views
- No renewable harvest area
- No passive solar heating
Each solar hot water panel has a dynamic profile. Generally a 4 sq. m panel is required for a 4 bed (5 person) family house on a 0.6 usage factor. For these studies the average usage is assumed to be 0.6 regardless of bed space for a 2.1 sq. m panel (the biggest unit size 4 person 2 bed)
Commercial units require very little hot water consumption. This is assumed to be 1kwh/m2/annum of floorspace. This is an underestimate for a live work area where hot water for showers, washing would still be required.
South facing units have PV integrated within balustrade units, again in a similar method of BIPV in glass laminates. These have been negiotiated in price for the project and will be 40% more than standard PV panels
PV from other areas i.e roof, pedestrian canopies, facades are devoted to site wide or commercial areas
Each residential unit has a turbine assigned to it with surplus turbines assigned to live work units. The only unit without dedicated turbines is the magnet showroom.
Manufacturer data on turbines
- This takes anticipated performance data with the average wind speed for the area (taken from DTI web site at 4.9 m/s) to calculate the energy production from renewable processes
- A turbine is assigned to each residential unit with additional turbines assigned to live-work units
- Live work areas have a electrical consumption of 44kW/m2/annum achievable through ZED specification of low energy lighting, TFT screens and office environment providing background lighting with local task lighting.
- All Live work assumed to have the same energy density. The Magnet showroom is assumed to have an energy consumption similar to that of an exhibition space of 57kWh/m2/yr based on Econ 87 figures.
- Residential does not achieve a electrical energy balance and the PV areas for commercial area is oversized
- Solar hot water is adequate for the residential but is oversized for commercial units. Due to pipe runs the solar hot water areas cannot be assigned to northern units.
- In this brief study it is assumed that the solar hot water load is reassigned but this will not be the case in the final building
- Sensitivity to achieve electrical balance- Zed. This aims to optimize the outputs electrically to see what figure each turbine has to produce. The figure comes to between 1450-1600 kWh/annum
Maximizing electrical production
- By installing PV on the pedestrian balustrade this lowers the load required again on each of the turbines to between 1300-1400kWh/annum
- Using bench mark figures and maximizing solar hot water panels-SHWecon 19
- As conclusion the solar hot water should be removed from the magnet showroom but retained for any live work units.
- Sensitivity analysis on workspace at residential energy density By assigning the commercial areas the same energy density as a one bed flat (the largest energy density of the residential units) as a sensitivity analysis. The result is higher than ZED spec of 44kWh/m2/annum
- As conclusion the solar hot water should be removed from the magnet showroom but retained for any live work units.
Conclusions
- One solar panel should be allowed for each south facing residential and live work units only
- Wind analysis will dictate whether partial load wind turbines supplemented with the roof PV are used for the residential units or a larger tower shared system is used in the same method as the wood pellet boilers
- The assumption that Magnet will use econ87 rates of consumption should be valid
- With higher energy consumption from the magnet store turbines have to produce same energy balance (these however are attached to mainly residential aspect)
- Defining areas of energy matching and assignment whether this is a tower or individual solutions is of prime importance. Further investigation of a site-wide or tower grid should be analysed.
