14/03/2012

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A bungalow ‘eco-retrofit’ in CSG- Superhome No.83(www.superhomes.org.uk)

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Tring in Transition

13th March 2012

“Rather than simply waiting for government to do it for us, we have to start making [change] in our lives and in the institutions of our society straight away.” (The Spirit Level, 2010)

Charles and Judy Ainger

Introduction - our bungalow ‘eco-retrofit’

History: conventional 2.5 bedroom bungalow, built 1950s, extended 1980s, sun room extension + eco-retrofit, summer 2008 (except where stated)

Space: heated living space ~125m2. Houses 2 to 3 people

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Starting point: � old gas (65% efficient) non-condensing boiler for heating (radiators + foil + control valves) & hot water; � 1950s cavity walls with cavity insulation, double glazing, reasonable loft insulation.

‘Baseline’ starting point on CO2 for ‘house’ - heat, light, water -was 7.4 tonnes CO2/yr. ‘Low hanging fruit’ on insulation was already done.

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Introduction – things to consider.. Our start position was in red

There are ‘low hanging fruit’ actions relevant to all

properties: loft & cavity wall insulation, low energy light

bulbs, double glazing, maybe floor insulation.. (we were

on gas for heating & HW.)

Beyond that the best combination of actions depend on:

� your objectives: less CO2 (major reduction), get off fossil

fuels, less running cost, more comfort? and:

� your property details, your starting point, and your £ to

invest ( > £100k - major extension and roof renewal etc)

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Summary – bungalow eco-retrofit 2008

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Biomass (wood

pellet) boiler:

heating radiators

+ hot water. Runs

at 10 kw; 4t/yr

pellets. 3t hopper

in shed, deliveries

2 x per yr.

Low Energy

bulbs & fittings:

throughout house.

Solar Thermal

(east & west), 12

+ 12 evacuated

tubes. (2005)

Rain water harvesting:

110m2 roof area; 3,300 litre

tank.

Passive solar sun room,

5m x 5m. Washing, drying,

pot plants, gardening; some

heat input into house

ventilation system.

Solar PV: 2.4 kW peak, 20

panels, 2 DC>AC inverters

(2003)

Extra insulation, – extra in

loft, roof, dormers, garage -

house wall, front door. Plus

Sealed ventilation – to 8.6

pa, draughts sealing, MVHR

[Mechanical Ventilation with

Heat Recovery] system.

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Solar PV – electricity generation (2003):2.4 kW, 20 panels, 2 DC>AC inverters

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Annual solar electricity generation: 2,200kWh, replacing mains, 60% out of annual 4040 kWh. CO2 saving = 1200kgCO2/yr (16%)

20 panels

on 35 deg

South-

facing

roof

2 DC-AC inverters,

on inside of gable

wall in loft

Solar thermal – hot water (2005): 12 (east) + 12 (west) evacuated tubes.

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24 tubes, 2 pumps, two-coil HW tank, controls. (does ~ all hot water, May – September)

� Saved ~1240 kWh/yr, out of 2800 for HW. This saves 230kg CO2/yr with the old gas boiler (OGB), but only 30kg/yr with the wood pellet boiler (WPB).� But the 2 pumps use extra 35 kWh mains electricity/yr = + 20kgCO2/yr.� So net kgCO2/yr saving = -210 (v. OGB); but only -10 (v. WPB) – pumps cancel out pellets saving.

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Low Energy bulbs & fittings, throughout

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� Saved ~730 kWh/yr – 65% out of ~1130 kWh/yr for lighting� CO2 saving = 390kg/yr (5%)

Where am I losing heat?Thermographic imaging – for insulation

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Front

Back

Decided on action on dormers, front door & sloping roof insulation –but in hindsight, sloping roof doubtful, maybe more on windows?

� Thermographic

Survey

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� Insulation/MVHR saves 15% (4000kWh) of heating energy (& cost). This saves 780kg CO2/yr with the old gas boiler (OGB), but only 90kg/yr with the wood pellet boiler (WPB).� But the fan runs 24hrs/365days; extra 900kWh mains electricity/yr = + 475kgCO2/yr.� So net kgCO2/yr effect = -300 (v. OGB) - only

40% of saved gas energy; but + 385 (v. WPB)

� Sloping roof insulation� Ducts, fan, heat exchanger� 80% exhaust air heat recovery claimed.

Roof Insulation + MVHR - Mechanical Ventilation with Heat Recovery

Air-tightness: for comfort - fresher air, less condensation & dust, with MVHR

� Air Permeability Test

achieved 8.6

m3/(h.m2), vs. target

of 10.

� Cost-effective for

comfort; not for CO2?

� But helps allow boiler

off longer in summer..

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Sealed:� floors with hardboard/new wood floor� skirting rails with sealant� rubber draft excluders on doors

Air Permeability Test Kit

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Windhager biomass (wood pellet) boiler: heating via radiators, + hot water.

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� Replaces fossil fuel gas (boiler @ 65% eff.) with 22,000 kWh (4.6 tonnes) of ‘renewable’ wood pellets. But; fans, pumps & ignition add 350 kWh/yr mains electricity, with CO2 =190kg/yr � CO2 saving = 4600kg/yr (62%) – without the other additional items; � these further reduce pellet use to 3.84 tonnes, 18,250 kWh/yr

Sept*-Oct*

Oct*-Nov*

Nov*-Dec*

Dec*

Jan

FebMarch

April

0

20

40

60

80

100

120

0 5 10 15

Boiler efficiency %

Heat demand, degree days K/day [*= part month]

Boiler efficiency vs. Heat demand/day

Heating season 2008-9

� 25 kW capacity, running at 10 kW; � 100% automatic –ash cleaning once/yr� automatic feed from 3 tonne hopper in shed; truck delivery 2 x/yr� usually runs October to April – 7 months.

Efficiency varies v. demand: av. 79% (v. claimed 86%)

Wood pellet delivery comes in bulk..

You need hopper

space & lorry access

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Passive solar sun room, 5m x 5m – (not ‘heated space’)

� washing, drying, pot plants, gardening (‘cold frame’)

� some heat input into house ventilation system

� views of garden

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� ‘passive solar’ effect contributes to energy efficiency, but not quantified � clothes drying saves tumble dryer (but we didn’t have one anyway)

Rain water harvesting, for (garden, 1 toilet, wash m/c) saves ~17,000 litres/yr mains water

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Tank 3.3 m3 Soakaway

Roof

area

110m2

Pump, control valves & meters

110m2 roof area, 3300 litre

tank, membrane pump

� Old centrifugal pump used

more energy and +25% more

CO2 than mains water

� New membrane pump uses

same energy and CO2 as mains

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RWH: comparing pld Stormbank pump, new Aquality pump and mains water over 12 months

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Pump system Storm

-bank

Aquality

+ st’by

Aquality

no st’by

Veolia

Water

Comments [Stormbank is centrifugal pump; Aquality

is a membrane pump]

Volumes

Mains water/yr (m3) 47.5 Use = ~65 l/h/d. [UK av 150]

RWH/yr (m3) 17.2 17.2 17.2 About +1/3 on mains water = 24 l/h/d

CO2e

Water supply:

kg CO2e/m3

0.98 0.69 0.37 0.36 ‘No s’by’ Aquality just about matches mains water CO2e

Sewage: kg CO2e/m3 0.32 0.32 0.32 0.32 All at Thames Water average

Water & sewage

kg CO2e/m3

1.30 1.01 0.69 0.68 Adding water and sewage

Kg CO2e/year 55 49 44 44 = Mains vol @mains CO2e + RWH vol @RWH CO2e.

[Compare with house total of ~ 1700]

Overall comparison – 2 people in bungalow, with RWH

Mains water saving 17.2 =

27%

17.2 =

27%

17.2 =

27%

0 Cf. 65 m3/yr for 2 people

£ Saving vs. all mains

water

22.36 =

13%

23.56 =

13%

24.90 =

14%

0 Cf. £177/yr

Extra Kg CO2e/yr +11 +5 +0 0 Cf. 44 kg CO2e/yr. Gas heating of hot water is ~ 9 x this

Logic and lessons – approx installation, operating & maintenance costs, and CO2

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LH column is the original BASELINE; middle columns show the effect of each option

separately, on all day heating programme, compared with Baseline. RH column is the

WHOLE HOUSE AS IT IS NOW, in combination. (Costs are rounded, so columns and rows

may not add up.). NB: operating costs are old – see next slide for latest.

Total costs BASELINE:

old gas

boiler

Low

energy

lighting

Wood

pellet

boiler

Solar PV

electricity

(2003)

Solar hot

water

(2005)

Insulation

+ MVHR

Rain

water

Harvesting

WHOLE

HOUSE AS

IT IS NOW

Comments

Capital installation costs, for each option (£)

Equipment 0 1000 16000 (alt

8600?)

14000 6500 2000

(MVHR)

2000 41500 To outside

supplier

Civ./Build.

Wk.

0 0 8000 0 200 33000 9000 50000 Will have

some – it

depends..Fees 0 0 1000 0 0 4500 1500 7000

VAT 0 200 2000 700 300 5500 2000 10700 5 or 17.5%

Other costs 0 0 0 0 0 4000 2500 6500 Eg. garden,

temp. AccomTotal capital 0 1200 27000 14700 7000 49000 17000 110000

Total annual energy operating costs, with each option installed (£/year 2009 )- *actual costs of gas, electricity, wood pellets.

Total energy 1800 1700 1500 1500 1800 1750 1800 1100

Maintenance 80 80 185 80 150 140 130 375 It depends!

Total

operating

1900 1800 1700 1600 1900 2000 2000 1500

Operating

Cost saving %

Base case

0

5% 11% 16% (-1%) 1% (-1%) 23%

Carbon emissions (tonnes CO2/yr)

CO2 emissions 7.5 7.0 2.75 6.0 7.0 7.0 7.5 1.5

CO2 saving % 0 5% 62% 16% 3% 4% (-3%) 78%

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Utility costs (at today’s prices) and CO2

- average over last few years

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Utility:

Wood

Pellets

(Tonnes)

Solar Hot

Water

(kWh)

Mains

electricity

(kWh)

Solar PV

electricity

(kWh)

Gas

(kWh)

Mains

Water

(m3 )

Rain

water

(m3)

TOTAL Comments

Annual Quantities (Average over last 2 to 4 yrs)

Used per yr. 3.84t 1240 2215 1957 173 48.6 17.2 NA

Annual Costs* (at today’s rates - £)

Day rate: 0 0 53.07 0 77.75* 34.68 0 NA

Quantity

rate:

769.92 0 287.29 0 7.27 74.79 0 NA RWH pump energy

cost already covered

Gross cost: 769.92 0 340.36 0 85.02* 109.47 0 1304.77

Subsidy: 211.27 128.60* 339.87 Govt. FiT and Good

Energy’s RH credit

Net cost: 769.92 0 340.36 -211.27 -43.58* 109.47 0 964.90

* Gas connection used for cooking hob only. Day rate v. high but worth it because of Good Energy RH credit

Annual CO2 emissions (kg)

a) Std elec: 461 0 1189 0 32 33 0 1715 Buy std. Electricity

b) GE elec: 461 0 0 0 32 33 0 526 With GE 100% RE

Lessons – invest cumulatively, in a logical order, up to your targets

The three different objectives may lead to different orders of investment.

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Reduce CO2 Reduce Fossil Fuel kWhReduce running cost £

But:� after doing Low Energy Lights + Wood Pellet Boiler + Solar-PV, + Solar –Thermal, adding Insulation/MVHR and Rain Water Harvesting slightly worsens all 3 results.� and, going for a New Gas condensing Boiler would be most ‘efficient’, in benefit per £ - but saves only 16-22% against each objective.

BL 7335

LEL

+WPB

+S-PV +S-Th

+In/MV

+RWH

NGB: 0.52kg/£

0

1000

2000

3000

4000

5000

6000

7000

8000

-50000 0 50000 100000 150000

Reduction in kgCO2/yr

Installed cost £

BL 32800

WPB

+LEL+S-PV +S-Th

+In/MV+RWH

NGB: 2.8kWh/

£

0

5000

10000

15000

20000

25000

30000

35000

0 50000 100000 150000

Reduction in kWh/yr

Installed cost £

BL 1915

LEL

+S-PV+WPB

+S-Th

+In/MV

+RWH

NGB: £0.12/£

0

500

1000

1500

2000

2500

-50000 0 50000 100000 150000

Reduction in £ running

cost/yr

Installed cost £

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Comparison of actions – other factors beyond CO2, kWh and £ costs

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Action: Solar PV

electricity

Solar

Thermal

H Water

Wood

Pellet

Boiler

Low

Energy

Lights

R-water

harvest-

ing

Insulate

(> basic)

MVHR,

air

sealing

Installation disruption?

Low Medium High V. Low Medium High High

Extra on-costslikely?

No No Yes No Yes Yes Some

‘Fit & forget’? (Min. maintenance&easy Controls)

Yes Quite –

auto

Quite –

auto to

manual

choice

Yes Quite -

auto

Yes Quite

Free from fuel supply & cost?

Yes Yes No Yes Yes Helps Helps

Adds comfort? NA NA NA NA NA Yes Yes

Lessons – in hindsight! What would we do differently, if only we had known..

Insulation and MVHR:

� The thermograph actually showed that the main roof was not bad; but windows were poor: so still do dormers, but then look at triple glazing windows, floor insulation, not sloping roof?

� The MVHR has been worth it for comfort ; and helps us close down the Wood Pellet Boiler [WPB] heating for longer – but don’t run it 24/7 in summer?

Renewable energy generation:

� If going ‘wood-burning’ think very hard about auto or manual – if auto, what space and road access for bulk hopper and filling? - and spend longer getting smaller ,cheaper model?

� Heating alternatives: look at air source heat pump (we had no space for ground source), maybe with a new condensing gas boiler for coldest. Also, consider Sterling engine CHP

� Low Energy Lights and Solar PV are great. But might not have done solar thermal, if we had installed renewable heat (like the WPB) first.

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And, for Government CO2 policy – what logic is sensible, up to their targets?

Graph shows ‘normalised’ costs and CO2, per m2 of heated house space*

� Can compare between properties – here, ours, and another one

� Houses have different start points – so ‘% reduction’ not very helpful as comparison

� Overall Govt. 80% CO2

reduction target for ‘retrofit’ houses implies ~ 15kgCO2/m

2

target – the red dashed line: better to set targets this way?

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0

10

20

30

40

50

60

70

80

90

-200 0 200 400 600 800 1000

Final KgCO2/m

2 area

£ installation cost/m2 area

Cumulative £ investment vs. kg CO2

reduction achieved, normalised per m2

BL

70% red

BL

84% red, without Ins/MVHR

+ Ins/MVHR

79%red

*So as not to favour those with big houses, also target kgCO2/occupant?

Our action in the context of a typical UK household - in tonnesCO2/yr

� House: water, electricity, heat = 8.0

� Transport: Car, flights, travel = 9.6

� Shopping: Food, shops, waste = 6.0

This saving on the house is approx.

= one person’s return flight to LA per year (Atmosfair: 6080kg)

(Guardian, ‘Earth’ Aug 2002; from

International Energy Agency, and

www.risingtide.org.uk)

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In one year, the average British household generates this CO2

Our start was 7.4Our saving was 5.7 [6.9] (77% [93%] less)

Our final was 1.7* [0.5]**(recalculated after 4 year’s operation)

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Our bungalow ‘eco-retrofit’– summary and lessons learnt

There are ‘low hanging fruit’ actions relevant to all properties: loft & cavity wall insulation, low energy light bulbs, probably double glazing, maybe floor insulation..

After that the best choice of actions depends on your objectives: less CO2, get off fossil fuels, less running cost, more comfort?

And, for the renewables heating/insulation choices particularly: it depends on your property details, your starting point, and your £ to invest [Our boiler, solar thermal and insulation were more expensive than likely average]

The sequence and total target of investment matters, and tells you the right point to switch from investing in insulation – less energy –to renewables – low carbon energy

Its fun doing it (mostly!) and very satisfying when you’ve done it...

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And – as a community response..Low Carbon Chilterns Co-op Ltd

� 10 Founder Members from individual Transition Town groups -Change4Chalfont, Chesham, Amersham, Low Carbon Jordans - started meeting as 'Energy Group' in August 2011.

� Formed a ‘bone fide cooperative’, registered by the FSA as IPS No. 31454R, on 7 November 2011. Aims:

“to reduce carbon emissions by helping the community to save energy and generate renewable energy.”

� In January 2010, won ‘LEAF’ funding to do survey of Chilterns, and prepare a business plan; will be done by 31 March..

� We need your help:� As Members, with time, contacts, or expertise to contribute � As contacts with Community Buildings, the focus of our business plan � As potential investors, investing £50 - £20,000, earning 3 or 4%

interest plus EIS tax relief;

We'd like to hear from you: If you are interested in our aims and plans and want to know more, please contact us at:

lowcarbonchilterns@yahoo.co.uk

(www.lowcarbonchilterns.org.uk)24

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And finally .. seen on a mug (sic) in a New York diner

“So-called global warming is just a secret ploy by

wacko tree-huggers to make America energy

independent, clean our air and water, improve the

fuel efficiency of our vehicles, kick-start 21st-century

industries, and make our cities safer and more

liveable.

Don't let them get away with it!”

Thanks for listening – questions?

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