Greentown: a detailed feasible study for a future low-carbon town

Transcription

1 Greentown: a detailed feasible study for a future low-carbon town Dr Mike Page University of Hertfordshire Jo Southernwood Carbon Minded Ltd. and IERC

2 Overview Background: the scale of the need for low-carbon housing The Cube Project and its extensions Greentown the question assumptions and details a model house the simulation results Conclusions

3 From Roger Pielke Jnr.

4 Joseph Rowntree Foundation, Distribution of Carbon Emissions in the UK: Implications for Domestic Energy Policy (2013)

5 Pro-environment behaviour change: In discussing pro-environment behaviour change, we (Page & Page, 2011, 2014) have identified what we call the HOT topics: Habits Opportunities Thoughts The Cube Project is one way in which to demonstrate carbonsaving opportunities 5

6 The Cube Project: To design and build a compact home in which one person or a (friendly) couple could live comfortably and with modern conveniences with a minimum impact on the environment. To showcase the best low-energy techniques and technologies, that could be applied to any sized building We aimed for energy/carbon neutrality on average, with low resource use and low embodied energy. (We do not expect everyone to live in a Cube)

7 Important features: Timber-frame structure, inc. Passivhaus triple-glazed windows/door highly insulated; low embodied energy; FSC or PEFC certified; no wet trades; rigid; maintainable Air source heat pump with low temp heating system high efficiency; lowest emissions; safe ; grid based (and hence able to be decarbonized) heat recovery ventilation Solar photovoltaic panels on southern aspects 3kW peak output; 280W average annual power; energy neutral over year; no overheating; Monopitch roof (implications for urban design)

8 Important features (contd.) LED lighting with absence detectors High efficiency; good colour temp; good CRI; dimmable; zero mercury; instant on Low energy appliances A++ fridge and washing machine Induction hob; combination microwave oven; LED TV; Low-flow water outlets Everything that we chose can be used in any sized building.

9

10

11

12 QB2 on George Clarke s Amazing Spaces

13

14

15 Extensions of the Cube Concept to sustainable urban development: We have a preliminary design for a comfortable home (the Sugarcube House) based on a 7.2-metre Cube. This could be configured as a four-bedroom house, or as a flat and a separate maisonette. Could be terraced, semi-detached or detached The Sugarcube House is much better than energy/carbon neutral over the year, has low embodied energy, and is designed to be built in around 2-3 weeks.

16

17 Greentown: the question How feasible is a UK town that is zero-(low-) carbon at all times? We simulate a new-build town of 10,000 Sugarcube houses, with 40,000 residents (restricting ourselves to domestic-energy balance) Energy balance is calculated for every hour for four years between 2011 and 2015

18 Greentown energy sources: Within Greentown: roof-mounted solar PV, ambient heat Outside Greentown: a fair share (40,000/64,000,000) of Grid-connected wind resource, on-shore and off-shore Tidal (stream, lagoon) Biomass (short rotation) Nuclear

19 Greentown energy demands: Domestic electricity supply Domestic heating and hot water: through air-source heat pump of variable coefficient of performance (COP), dependent on outside temperature (which we know for every hour) Conservative assumptions, e.g., that all houses are detached (they wouldn t be)

20 Energy balance: If Greentown is to not going to pass the buck, then does not only need to be zero-carbon on average; it needs to be zerocarbon at all times This entails an ability to store energy, perhaps at seasonal timescales. But how big (and expensive) is the battery?

21 Greentown model house: Monopitch roof at 20 12kWp of solar PV Uninsulated sunspace Passive solar gain in winter, shading in summer Walls 0.2W/m 2 K, Windows 0.8W/m 2 K, heat recovery ventilation 50% Terraced would be better, but we model as detached

22 Greentown solar resource: 120 MWp photovoltaics, with a 92% effective angle (50% South; 25% each East, West) We have meteorological data that gives the incident solar energy (kj/m 2 ) for a horizontal surface in Coventry (MIDAS dataset, courtesy BADC) How do we estimate the output of each 1kWp roof-mounted PV, given these insolation data?

23 Ouput of 2.66kWp PV sysytem A roof in Leicester (uksolarpowerdiary.co.uk) with 2.66kWp of solar PV vs. Coventry insolation Insolation (KJ/m2/h)

24 Greentown wind resource: Wind power on the grid from gridwatch.co.uk to get a grip on variability Uprated to reflect almost linear growth in the wind fleet between 2011 and 2015, and then linearly extended by a future-growth parameter (so all multiples are relative to 2015 fleet), and multiplied by 40,000/64,000,000 Linear uprating probably overestimates wind variability.

25

26 Four years of renewables Wind (max scale = 35MW) Solar (max scale = 100MW) plus a fair share of low-carbon baseload, modelled here as a constant value

27 Electricity demand: Heat demand (electric): Average domestic electricity demand (W) by month/hour 4.5 total electrical power for heat (kwe) Dec/Jan Feb/Nov Mar/Oct Apr/Sep May/Aug Jun/Jul Outside temperature

28 Storage is conceived as a combination of: A series of electric vehicles whose batteries are able to absorb some degree of short-term variation A big battery that is limited to a particular size and has various adjustable parameters like daily loss, charge/discharge efficiency. The size of the big battery is measured in Wembley Ikeas

29

30 Battery contents (in MWh) by hour over four years

31 Homes as renewable-energy resource: The UK needs to build around 4 million homes in the years up to million buildings like the Sugarcube House, would provide installed solar capacity of around 36GW, without any need for additional land. Buildings are a particularly suitable substrate for solar generation. Energy storage is the key remaining issue. Or should we just make up with gas?

32 So why are we not building Greentown(s)?

33 Thank you for your interest For more information please see