1. Sustainable Architecture System Design
By A-Team: Chris Aoun, Hakeem Buge, Edmund
Chan, Matei Predescu & James Taylor
The following poster summarises the energy systems installed
throughout the house.
Ground Source Heat Pump
• A ground source heat pump (GSHP) was selected for the property. A biomass boiler was considered, but a GSHP proved to
be a more cost effective option. It receives a higher RHI per kWh, and does not require a wood pellet fuel.
• Kensa Engineering Ltd, the local supplier, will provide a single phase 8kW heat pump, which is ideal for the house of study.
• The heat pump will utilise a slinky design, and has a rated power of 8kW in single phase and a COP of 4.14, which draws
2kW of PV electricity.
• It will heat up a Dimplex PSW100 100L buffer tank to 30°C, which stores sufficient heat when running 4 hours/day. The
buffer tank will cost £248.
• The completely sealed buffer tank leaves no hazard of Legionella.
• The remaining 6kW heat comes from the ground and is redeemable for RHI.
Rainwater Harvesting System
• In an attempt to reduce the mains water consumption, the
house will benefit from a rainwater harvesting system.
• The average annual rainfall for the site in question is 1375
mm/year (Met Office, 2015). Using an estimated available
roof area of 138 m2 and an average roof angle of 40°, the
total potentially available amount of rainwater is around
120,000 litre (120 m3).
• The optimum tank size has to give about 18 days of
storage, which equates to 5 % of the annual yield
(Nicholls, 2008).This gives an initial requirement of 6000
litres. However, this is considered to be the best case
scenario, making it less probable. Choosing a tank size of
5000 litres is more realistic.
• Due to lack of space and the size of the collector tank, the
system will use an underground storage tank, buried
adjacent to the house that can be accessed through a
manhole cover, the underground installation provides the
added benefit that the cool and dark environment
discourages the formation and growth of algae and
bacteria.
Rain water harvesting system flowchart
Heat Exchanger
150MMx150MM
150MM x 150MM
150MM x 150MM
Outside
Inside
150MM x 150MM
Return:
Kitchen
and Bathrooms
Supply:
Bedrooms
Controller
Air filters
Centrifugal fan
150MM x 150MM
150MM x 150MM
Inlet air
Exhaust
air
Mechanical ventilation heat recovery:
• Mechanical ventilation heat recovery (MVHR) will be used throughout the property. This is to ensure the house is properly ventilated and meets the air
change per hour that is required, making it comfortable for its inhabitants.
• Heat recovery has been implemented into the system to ensure valuable heat produced by the renewable energy systems in the house is not lost.
• Bull nose vents will be used throughout the house.
• The MVHR unit that will be used in the house is a Vent Axia Lo-Carbon Sentinel Plus B. Vent Axia have quoted that the whole system, excluding
installation will cost £3612.
• This specific MVHR system was selected due to its high heat recovery efficiency of 90%.
Mechanical heat recovery system
Solar PV
• A 6.0 kWp solar PV system has been designed for the house. The system is comprised of 24 Renesola enhanced
polycrystalline 250W panels, covering a roof area of 44.41 metres squared. Two 3.6kWh Samsung SDI lithium ion batteries
will be used to store energy not immediately used by the property. They come with an integrated inverter which has a
maximum power input of 6.6kWp.
• The PV array will be situated on the south east facing roof of the property.
• The reason for choosing this type of panel is that it is currently one of the most cost effective at a price of 46.5p/W but
furthermore it is space effective at 150W/m2.
• PV was selected to power the house due to its sustainable nature and to avoid paying the £50,000 grid connection fee.
• PVSyst was used to design the system. Based on the tilt angle, orientation and several other conditions, the predicted output
is 7071 kWh/year.
• The annual electrical consumption was found to be 6026kWh meaning that the PV system easily provides enough electricity
for the house consumption and also the capability of storage.
• The total system cost, including installation, PV panels and batteries, has been calculated to be in the region of £15,000. The
following graph shows the expected payback of the system, taking into account the feed in tariff and electricity bill savings.
Energy schematic
Sewerage
The absence of service from the mains sewerage fashions the need for an onsite sewerage
treatment plant that requires low maintenance, isn’t aesthetically unpleasant, is inexpensive and
meets regulation standards (Section 2, Document H: Drainage and wastage disposal). To achieve this
we opted for a system below:
A septic tank connected to vertical flow reed beds.
•
The size of the reed bed: 12-15m2
• 2900L septic tank
• Humus tank
House costing table
Expense Price
Cooker £700.00
Kettle £24.00
Fridge + Freezer £549.00
Extractor Fan £900.00
Dishwasher £300.00
Microwave £60.00
Toaster £19.50
Blender £20.00
Washing Machine £850.00
Dryer £600.00
Heat Pump £14,000.00
Mechanical Ventilation £3,010.00
Roof £2,000.00
Insulation +Framing (walls&roof) £67,024.00
Excavation £18,000.00
Foundation £8,000.00
Underfloor Heating £15,000.00
PV panels £2,947.00
Thermal £3,050.00
Battery/Inverter (x2) £10,000.00
Sewerage £3,750.00
Windows £40,000.00
Back up bio fuel £756.00
Curtains £380.00
Recycling/Waste £44.00
Solar Lights £70.00
Garage £18,600.00
Guttering £2,250.00
Doors £1,050.00
Flooring £16,126.00
Wiring £6,500.00
Plastering £15,120.00
External Cladding £2,700.00
Plumbing £1,600.00
Lighting £469.00
Rainwater Harvesting System £3,152.00
Chip board £1,726
Engineering timber £7,980
Low Tog Carpet £5,270
Stairs £1,150
Labour Costs £34,000.00
Miscellaneous costs £60,000
Total £369,746.50
Budget £424,000.00
Cost per m2 £1,395.27
Cost per m2 budget £1,600
Percentage of budget 87.20%
Smart energy management
• The energy control system will comprise of a main
control box that manages the interaction between all
the energy systems installed in the house, with
additional controls of various appliances.
• Smart energy management systems can be used to
ensure efficient management of the time-flexible loads
around the house for example if during the day the PV
panels operate at, or close to full capacity, the
washing machine or the dryer could automatically
come on if loaded at midday, in order to use energy
when it is most readily available.
• The system would be able to gather additional
weather forecast information, in order to
accommodate for shifts in the daylight pattern,
therefore ensuring the different appliances would
come on when the system is generating the most
amount of energy possible.
• All of these features should be automated and work
without any input from the inhabitants. However, if the
situation calls for a change in scheduling or complete
interruption of the cycle, the occupants can access the
system through any wireless connection, using a
purpose-built app.
Underfloor:
•The property will have an underfloor heating system in order to fully utilize the ground source heat pump that is present.
•NU-Heat will supply and install the underfloor heating which will have an estimated cost of £15,000.
•The floor finish throughout the house will be a mixture of engineering timber and low tog cream carpet. The tog value of the carpet being used is
1.56.
•A floating floor system will be used for the property as it works well with the desired floor finishes. Additionally, it is easy to install on a timber
frame. The following image shows the underfloor system that will be used.
(NU-Heat, 2015)
•As different temperatures will be required throughout the house, different areas of the house will be separated into zones, each containing
a thermostat. From these thermostats the temperature of each zone can be controlled.
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Solar Thermal cashflow
Solar Thermal
• The houses solar thermal system will comprise of three flat plate AES Supremacy Solar 2.5 AR flat-
plate collectors, and a custom made Telford 300L cylinder.
• The solar collectors will be situated on the south west facing roof.
• The solar thermal system will be used primarily to heat the houses domestic hot water, but has the
capacity to assist with the underfloor heating.
• The cylinder will contain two heat exchangers. The primary heat exchanger will be supplied by the flat
plate collectors, with the second heat exchanger a backup that can be supplied by the ground source
heat pump.
• A closed loop system will be used utilising a heat transfer fluid, as it ensures a reliable winter
performance.
• A SAP calculation was performed to calculate the deemed output of the solar thermal system. The
estimated output is 1983 kWh/year
• The whole solar thermal system including installation will cost £4050, with a predicted payback of 14
years.
Back-up generator
A diesel generator will be included in the design
to act as a back-up for a finite number of days
per year, when the PV will not be able to meet
the house electricity requirements, due to lack of
solar radiation. The proposed generator has
4.2kW rated power, which should suffice for the
long winter nights. However, the generator can
be retrofitted to operate on biodiesel in an
attempt to further decrease the overall carbon
footprint of the house.
Specifications:
• Model: DHY8000SE
• Max Output: 6kVA/6kW
• Engine Speed: 3000 rpm
• AC frequency: 50 Hz
• Battery (Ah): 12V 36a/h
• AC Power Factor: 1.0