Outline. Thermal storage for low carbon buildings. Effect of global warming on design summer year. Environment impacts of buildings

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Thermal storage for low

carbon buildings

Kenneth Ip

Centre for Sustainability of the Built Environment School of Environment and Technology

Built Environment Division

Kenneth Ip

http://www.brighton.ac.uk/csbe

Outline

• Background

• Basic principles of thermal storage in

buildings

• Recent thermal storage projects

undertaken by CSBE

• Conclusions

Environment impacts of buildings

• Buildings consume or are responsible for

– 40% of the world's total energy use – 35% of the world’s CO2emissions – 30% of raw materials consumption – 50% of ozone-depleting – 40% of municipal solid waste – …….

• In the UK

– approx. 50% total energy consumption and CO2emissions…

– Over 20% used to maintain indoor thermal comfort

(Source: WorldwatchPaper #124, UK DTI statistics)

Effect of global warming on

design summer year

DUNSTER, B. (2005) UK Housing and climate change - heavy weight vs. lightweight construction, London, Ove Arup & Partners Ltd.

Based on records of past 25 years

Solution for summer overheating?

Impact of global warming to

thermal comfort

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Impact of global warming to thermal comfort1 D U N S T E R , B . ( 2005 ) UK Hou s ing and c lim a te c hange -h eav y we igh t v s. ligh tw e igh t c o n s tr u c ti on , Lond on , O v e A ru p & P a rt ne rs L td . Lightweight Mediumweight Heavyweight Shading at 95% + ventilation up to 6 air changes per hour

Heavyweight Lightweight

Design options for applying

thermal storage in buildings

Basic options:

• Seasonal or diurnal storage

• Sensible heat or/and latent heat storage

Sensible thermal storage

for buildings

• By increasing/decreasing the temperature of storage medium without phase change

• Key factors: temperature difference, specific heat capacity

• Examples of storage media: concrete, brick, water

Latent heat storage

• By latent heat due to phase change of storage medium • Key factors: latent heat capacity,

phase change temperature • Potential added benefit: improved

thermal comfort

• Examples of storage media (phase change materials – PCM): salt hydrates and organic wax

What are phase change

materials (PCM)?

Benefits of using PCM

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Recent thermal storage

research projects

A. Seasonal thermal storage – sensible heat

1. Earth-sheltered buildings - Earthship 2. Ground heat exchanger - Earthduct

B. Diurnal thermal storage – latent heat

3. Solar PCM underfloor space heating

4. Solar/heatpump PCM hot/chilled water storage 5. PCM wallcovering

1. Seasonal storage: Earthship

Location: Stanmer Park, Brighton (EU Durabuild case study)

Earthship in

Stanmer Park, Brighton

Thermal storage by solid wall

behind glass

Thermal storage by

rammed-earth tyre-wall

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Temperature monitoring

• Rear wall in Main room • Side wall in kitchen • Soil temperature sensors at different depths and heights • Provide a thermal grid of the Earthship

Earthship Monitoring

1 metre N

Nest module / main room

Conservatory / sun space Hut module Soil temp Air temp humidity Solar

Weather station and

datalogger

Dome Dome solarimeter solarimeter Ambient air Ambient air temperature temperature sensor sensor Photovoltaic Photovoltaic panel panel Data logger 0 0.05 0.1 0.15 0.2 0.25 08/01/05 08/01/05 09/01/05 10/01/05 10/01/05 11/01/05 11/01/05 12/01/05 date sol a r r a di at io n i n kW .m-2 0 2 4 6 8 10 12 14 16 18 20 temp in °C

Measured Data: Global radiation

and internal air temperatures

Global solar radiation Main room air temperature Conservatory air temperature

External air temperature

• Building unfinished, not occupied. little planting

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‘Eco-heaven: a £500,000 mud house’

(Sunday Times 22nd_{April 2007)}

• “The 16 buildings …hillside overlooking the Channel near Brighton marina, called Earthships ….. made of mud, old tyres and tin cans ….Britain’s first self-sustaining eco-houses .. as much as £500,000 for three bedrooms”

• Electricity will be provided by wind turbines and solar panels.

• One metre thick outside walls will be made of earth-filled tyres

• Internal partitions will be made from old bottles and cans

2. Seasonal storage: Earthduct

Source: http://www.resource05.com/presentations/day2/Patrick%20Bellew2.pdf

Soil temperature - Brighton

0 744 1488 2232 2976 3720 4464 5208 5952 6696 7440 81848760 4 6 8 10 12 14 16 18 20

Soil Temperature profile Brighton (1-10m depth)

Tem p e rat ur e ( o C ) SoilT@10m SoilT@1m SoilT@2m SoilT@3m SoilT@4m SoilT@5m

First UK application

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Butterfield Business Village – Feb 2007

_{Performance evaluation}

• Lack of design information although

acknowledged as a Low or Zero Carbon

Emission technology

• Current study

– Review of thermal models

– Analysis by computer thermal simulation – Measurement and validation

– Performance optimisation

– Evaluate for potential use in the UK

Simulated results of outlet air

temperatures

0 4 8 12 16 20 24 14 18 22 26 30

(a) Outlet air temperature for different tube diameter (30m Length, 2m depth, air-velocity 4m/s)

Time(hrs) T e m p er a tur e( o C ) TAmbt. 100cm 20cm 50cm 60cm 80cm 0 4 8 12 16 20 24 14 18 22 26 30

(b) Outlet air temperature for different tube lengths (0.4m diameter, 4m/s air velocity, 2m depth)

Time (hours) T e m p er at u re ( o C ) 0 4 8 12 16 20 24 14 18 22 26 30

(C) Outlet temperature for different air velocity (0.4m diameter, 4m/s air velocity, 2m depth)

Time (hours) T e mpe rat ur e ( o C ) 0 4 8 12 16 20 24 18 20 22 24 26 28 30

(d) Outlet air temperature for various depoths (30m length, 4 m/s air velocity, 0.4m diameter)

Time (hours) T e mpe rat ur e ( o C ) 1m 2m 4m 3m TAmbt. 30m TAmbt. 40m 50m 60m 70m 80m TAmbt. 2ms 4ms 5ms 6ms 8ms

3. Diurnal storage: Solar phase change

thermal storage underfloor space heating

http://www.greenenergy.org.uk/sta/solarenergy/howwork.htm http://www.designbuild-network.com/contractors/water_supply/wavin-plastic/wavin-plastic2.html

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Recording and control

equipment

Test box

Underfloor pcm module

Heat exchange to pcm

Graph To Show Solar Panel Water Temperature Output Over Time 20/06/02 0.00 10.00 20.00 30.00 40.00 50.00 60.00 70.00 80.00 90.00 08 :4 3 09 :0 3 09 :2 3 09 :4 3 10 :0 3 10 :2 3 10 :4 3 11 :0 3 11 :2 3 11 :5 3 12 :1 3 12 :3 3 12 :5 3 13 :1 3 13 :3 3 13 :5 3 14 :1 3 14 :3 3 14 :5 3 15 :1 3 15 :3 3 15 :5 3 16 :1 3 16 :3 3 16 :5 3 17 :1 3 17 :3 3 17 :5 3 Time Te m p er at u re °C

Graph To Show Surface Floor Temperature Over Time Using A Solar Thermal PCM Space Heating System on 20/06/02

0.00 5.00 10.00 15.00 20.00 25.00 30.00 35.00 40.00 45.00 08 :4 3 09 :2 3 10 :0 3 10 :4 3 11 :2 3 12 :0 3 12 :4 3 13 :2 3 14 :0 3 15 :2 3 16 :1 3 16 :5 3 17 :3 3 18 :1 3 18 :5 3 19 :3 3 20 :1 3 20 :5 3 21 :3 3 22 :1 3 22 :5 3 23 :3 3 00 :1 3 00 :5 3 01 :3 3 02 :1 3 02 :5 3 03 :3 3 04 :1 3 04 :5 3 05 :3 3 06 :1 3 06 :5 3 07 :3 3 08 :1 3 Time Su rf ac e Floor Tem p er a tur e °C

Results

• Results being analysed

4. Phase change thermal

storage – hot and chilled water

• Partner of an EU funded project - Endohouse

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Heat pump - heating & cooling

M a in s w a te r H o t s to r e C o ld s to re H e a t p u m p H o t w a te r C i rc u l a tin g p u m p H o t w a te r s to re H e a t in g M o d e H e a t d i st rib u tio n s y s te m H o t w a te r s t o re H o t w a t e r C o o li n g s y s te m H e a t p u m p C o l d s t o re H o t s to r e M a in s w a te r C i r c u l a t in g p u m p C o o l i n g M o d e Cold Store Hot Store Mode 1: Charging Mode 2: Delivery Mode 3: Backup Heatpump Heating Cooling Hot Water Backup system Endothermic System Operation Integrated roof collector

Prototype - PCM thermal store

Store size reduced by up to 80% 2m3Cold (0-20C): 2m3Hot (30-50C):

Results

0 10 20 30 40 50 60 70 80

Phase change region Phase change temperature

Temperature gap 0.42 kg/s temperature range 25oC - 70oC 0.19 kg/s temperature range 20oC - 0.40 kg/s temperature range 19oC - 68oC

0.38 kg/s temperature range 21oC - 68oC

PCM store inlet temperature 40 °C - 71 °C flow rate 0.42 kg/s

0 10 20 30 40 50 60 70 80 0 1.6 3.2 4.8 6.4 8 9.6 11.2 12.8 14.4 16 Time (hours) Tem perat ur e ( oC)

Phase change temperature Phase change region

Temperature gap Flow from H/W cylinder to PCM

Return from PCM store to H/W cylinder

PCM store inlet temperature 10 o

C flow rate 0.20 kg/s 0 10 20 30 40 50 60 70 80 0.0 0.3 0.7 1.0 1.3 1.7 2.0 2.3 2.6 Time (hours) Aver ag e P CM t emper at ure ( oC)

Phase change region PCM temperature start point 70 oC PCM temperature start point 57 o

PCM temperature start point 53 oC PCM temperature start point 63 oC

0 200 400 600 800 1000 1200 1400 1600 1800 0 20 40 60 80 100

Tem perature increase (deg C)

P e rcen ta g e en er g y st o red b y PC M ( % ) 70% PCM 60% PCM 50% PCM 40% PCM 30% PCM

Specif ic latent heat capacity 221 kJ/kg

5. Diurnal storage: Phase

change wallcovering

• To develop a Wallcovering containing

PCM

• Funded by Teaching Company Scheme

(now KTP)

• Industrial partner: Omnova Wallcovering

Co. Ltd

• UOB Innovation award 2006

Simulate optimum quantity of PCM

Manufacturing of

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Performance evaluation

Results being analysed

10.00 15.00 20.00 25.00 30.00 35.00 40.00 17 :4 3: 53 19 :3 8: 53 21 :3 3: 53 23 :2 8: 53 01 :2 3: 53 03 :1 8: 53 05 :1 3: 53 07 :0 8: 53 09 :0 3: 53 10 :5 8: 53 12 :5 3: 53 14 :4 8: 53 16 :4 3: 53 18 :3 8: 53 20 :3 3: 53 22 :2 8: 53 00 :2 3: 53 03 :1 8: 53 05 :1 3: 53 07 :0 8: 53 09 :0 3: 53 10 :5 8: 53 12 :5 3: 53 14 :4 8: 53 16 :4 3: 53 18 :3 8: 53 20 :3 3: 53 22 :2 8: 53 00 :2 3: 53 02 :1 8: 53 04 :1 3: 53 06 :0 8: 53 08 :0 3: 53 Time T e m p erat u re ( d eg .C ) Control chamber PCM chamber 18.5°C 18.43°C 31.87°C 35.48°C ΔT = 3.61°C ΔT = 3.63°C 23.15°C 22.63°CΔT = 0.52°C 33.98°C 37.61°C a b

Conclusions

• Buildings are responsible for a significant proportion of

greenhouse gas emissions

• Global warming is likely to cause summer overheating in some existing and new buildings

• New or refurbished buildings should be designed to avoid future dependence of air-conditioning to counteract summer

overheating

• Thermal storage is a low or zero CO2emission technology for

maintaining indoor thermal comfort. It can help to achieve the

60% UK CO2reduction target by 2050

• There are numerous research opportunities to explore novel and conventional thermal storage design options to enhance the sustainability of new and existing buildings

Thermal storage group

• Thermal storage group

– Prof. Andrew Miller – Dr. Kenneth Ip – Ms. Dianne Dyball – Mr. Abdullahi Ahmed – Mr. Jonathan Gates

• For more information & publications

– Visit Centre for Sustainability of the Built Environment web site