Presentation on theme: "1 Concrete in Construction and the Impact of Climate Change Keith Tovey ( ) MA, PhD, CEng, MICE, CEnv Energy Science Director HSBC Director of Low Carbon."— Presentation transcript:
1 Concrete in Construction and the Impact of Climate Change Keith Tovey ( ) MA, PhD, CEng, MICE, CEnv Energy Science Director HSBC Director of Low Carbon Innovation CRed Carbon Reduction Concrete Society Meeting Norwich 30 th October 2007 CRed Recipient of James Watt Medal 5 th October 2007
2 ZICER Building Heating Energy consumption as new in 2003 was reduced by further 57% by careful record keeping, management techniques and an adaptive approach to control. Incorporates 34 kW of Solar Panels on top floor Low Energy Building of the Year Award 2005 awarded by the Carbon Trust.
3 Changes in Temperature
Climate Change Arctic meltdown Summer ice coverage of Arctic Polar Region –Nasa satellite imagery Source: Nasa 20% reduction in 24 years
5 Options for Electricity Generation in Non-Renewable Methods Nuclear New Build assumes one new station is completed each year after 2018.
6 Options for Electricity Generation in Renewable
7 Area required to supply 5% of UK electricity needs ~ 300 sq km But energy needed to make PV takes up to 8 years to pay back in UK.
8 Options for Electricity Generation in Renewable But Land Area required is very large - the area of Norfolk and Suffolk would be needed to generated just over 5% of UK electricity needs. Transport Fuels: Biodiesel? Bioethanol? Compressed gas from methane from waste.
9 Options for Electricity Generation in Renewable
10 Options for Electricity Generation in Renewable
11 Options for Electricity Generation in Renewable Output GWh per annum Sufficient for house in Orkney Save tonnes of CO 2
12 Options for Electricity Generation in Renewable
13 Solar Energy - The BroadSol Project Annual Solar Gain 910 kWh Solar Collectors installed 27th January 2004
14 Performance of a Solar Thermal System Data collect 9 th December 2006 – 30 th October 2007
15 House in Lerwick, Shetland Isles with Solar Panels - less than 15,000 people live north of this in UK! It is all very well for South East, but what about the North? House on Westray, Orkney exploiting passive solar energy from end of February
16 Opted Out Coal: Stations can only run for hours more and must close by 2015 New Nuclear assumes completing 1 new nuclear station each year beyond 2018 New Coal assumes completing 1 new coal station each year beyond 2018 Our Choices: They are difficult: Energy Security There is a looming capacity shortfall Even with a full deployment of renewables. A 10% reduction in demand per house will see a rise of 7% in total demand - Increased population decreased household size
17 Our Choices: They are difficult If our answer is NO Do we want to return to using coal? then carbon dioxide emissions will rise significantly unless we can develop carbon sequestration and apply it to ALL our COAL fired power stations within 10 years - unlikely. If our answer to coal is NO Do we want to leave things are they are and see continued exploitation of gas for both heating and electricity generation? >>>>>> Do we want to exploit available renewables i.e onshore/offshore wind and biomass. Photovoltaics, tidal, wave are not options for next 20 years. If our answer is NO Do we want to see a renewal of nuclear power Are we happy with this and the other attendant risks?
18 Our Choices: They are difficult If our answer is YES By 2020 we will be dependent on around 70% of our heating and electricity from GAS imported from countries like Russia, Iran, Iraq, Libya, Algeria Are we happy with this prospect? >>>>>> If not: We need even more substantial cuts in energy use. Or are we prepared to sacrifice our future to effects of Global Warming by using coal? - the North Norfolk Coal Field? – Aylsham Colliery, North Walsham Pit? Do we wish to reconsider our stance on renewables? Inaction or delays in decision making will lead us down the GAS option route and all the attendant Security issues that raises.
19 The Climate Dimension Heating requirements are ~10+% less than in 1960 Cooling requirements are 75% higher than in Changing norm for clothing from a business suite to shirt and tie will reduce clo value from 1.0 to ~ 0.6. To a safari suite ~ 0.5. Equivalent thermal comfort can be achieved with around 0.15 to 0.2 change in clo for each 1 o C change in internal environment. Care in design is needed to avoid overheating in summer and to minimise active cooling requirements Thermal Comfort is important: Even in ideal environment 2.5% of people will be too cold and 2.5% will be too hot. Estimate heating and cooling requirements from Degree Days Index 1960 = 100 Heavy Weight Buildings can help to reduce energy requirements in a warming climate.
20 The Elizabeth Fry Building 1994 Cost ~6% more but has heating requirement ~25% of average building at time. Building Regulations have been updated: 1994, 2002, 2006, but building outperforms all of these. Runs on a single domestic sized central heating boiler.
21 User Satisfaction lighting +25% air quality +36% A Low Energy Building is also a better place to work in Careful Monitoring and Analysis can reduce energy consumption. Conservation: management improvements – thermal comfort +28% noise +26%
22 The ZICER Building - Description Four storeys high and a basement Total floor area of 2860 sq.m Two construction types Main part of the building High in thermal mass Air tight High insulation standards Triple glazing with low emissivity
23 The ground floor open plan office The first floor open plan office The first floor cellular offices
24 Air enters the internal occupied space Return stale air is extracted from each floor Incoming air into the AHU Regenerative heat exchanger Filter Heater Air passes through hollow cores in the ceiling slabs The return air passes through the heat exchanger Out of the building Operation of the Main Building Mechanically ventilated using hollow core ceiling slabs as supply air ducts to the space Recovers 87% of Ventilation Heat Requirement.
25 Importance of the Hollow Core Ceiling Slabs The concrete hollow core ceiling slabs are used to store heat and coolness at different times of the year to provide comfortable and stable temperatures Winter Day The concrete slabs absorb and store heat Heat is transferred to the air before entering the room Winter day
26 Importance of the Hollow Core Ceiling Slabs The concrete hollow core ceiling slabs are used to store heat and coolness at different times of the year to provide comfortable and stable temperatures Winter Night When the internal air temperature drops, heat stored in the concrete is emitted back into the room Winter night
27 Importance of the Hollow Core Ceiling Slabs The concrete hollow core ceiling slabs are used to store heat and coolness at different times of the year to provide comfortable and stable temperatures Cold air Draws out the heat accumulated during the day Cools the slabs to act as a cool store the following day Summer night Summer Night – night ventilation/free cooling
28 Importance of the Hollow Core Ceiling Slabs The concrete hollow core ceiling slabs are used to store heat and coolness at different times of the year to provide comfortable and stable temperatures Warm air Summer Day Pre-cools the air before entering the occupied space The concrete absorbs and stores the heat – like a radiator in reverse Summer day
29 Heating energy requirement is strongly dependant on External Temperature. Thermal Lag in Heavy Weight Buildings means consumption requirements lags external temperature. Correlation with temperature suggests a thermal lag of ~ 8 hours. Potential for predictive controls based on weather forecasts Thermal Properties of Buildings Data collected 10th December 2006 – April 29th 2007
30 The space heating consumption has reduced by 57% Good Management has reduced Energy Requirements Acknowledgement: Charlotte Turner But this has only been possible because of realtively heavy weight construction
31 As Built GJ Air Conditioned GJ Naturally Ventilated GJ Life Cycle Energy Requirements of ZICER as built compared to other heating/cooling strategies Materials Production Materials Transport On site construction energy Workforce Transport Intrinsic Heating / Cooling energy Functional Energy Refurbishment Energy Demolition Energy 28% 54% 34% 51% 61% 29%
32 Comparison of Life Cycle Energy Requirements of ZICER Compared to the Air-conditioned office, ZICER recovers extra energy required in construction in under 1 year. Comparisons assume identical size, shape and orientation
33 Top floor is an exhibition area – also to promote PV Windows are semi transparent Mono-crystalline PV on roof ~ 27 kW in 10 arrays Poly- crystalline on façade ~ 6/7 kW in 3 arrays ZICER Building Photo shows only part of top Floor
34 Arrangement of Cells on Facade Individual cells are connected horizontally As shadow covers one column all cells are inactive If individual cells are connected vertically, only those cells actually in shadow are affected.
35 Use of PV generated energy Sometimes electricity is exported Inverters are only 91% efficient Most use is for computers DC power packs are inefficient typically less than 60% efficient Need an integrated approach Peak output is 34 kW
36 Engine Generator 36% Electricity 50% Heat GAS Engine heat Exchanger Exhaust Heat Exchanger 11% Flue Losses3% Radiation Losses 86% efficient Localised generation makes use of waste heat. Reduces conversion losses significantly Conversion efficiency improvements – Building Scale CHP 61% Flue Losses 36% efficient
37 Conversion efficiency improvements 1997/98 electricitygas oilTotal MWh Emission factorkg/kWh Carbon dioxideTonnes ElectricityHeat 1999/ 2000 Total site CHP generation exportimportboilersCHPoiltotal MWh Emission factor kg/kWh CO 2 Tonnes Before installation After installation This represents a 33% saving in carbon dioxide
38 Conversion efficiency improvements Load Factor of CHP Plant at UEA Demand for Heat is low in summer: plant cannot be used effectively More electricity could be generated in summer
39 Conversion efficiency improvements Condenser Evaporator Throttle Valve Heat rejected Heat extracted for cooling High Temperature High Pressure Low Temperature Low Pressure Heat from external source Absorber Desorber Heat Exchanger W ~ 0 Normal Chilling Compressor Adsorption Chilling 19
40 A 1 MW Adsorption chiller Adsorption Heat pump uses Waste Heat from CHP Will provide most of chilling requirements in summer Will reduce electricity demand in summer Will increase electricity generated locally Save 500 – 700 tonnes Carbon Dioxide annually
41 Target Day Results of the Big Switch-Off With a concerted effort savings of 25% or more are possible How can these be translated into long term savings?
42 The Behavioural Dimension Household size has little impact on electricity consumption. Consumption varies by up to a factor of 9 for any given household size. Allowing for Income still shows a range of 6 or more. Education/Awareness is important
43 Conclusions Hard Choices face us in the next 20 years Effective adaptive energy management can reduce heating energy requirements in a low energy building by 50% or more. Heavy weight buildings can be used to effectively control energy consumption Photovoltaic cells need to take account of intended use of electricity use in building to get the optimum value. Building scale CHP can reduce carbon emissions significantly Adsorption chilling should be included to ensure optimum utilisation of CHP plant, to reduce electricity demand, and allow increased generation of electricity locally. Promoting Awareness can result in up to 25% savings The Future for UEA: Biomass CHP? Wind Turbines? Lao Tzu ( BC) Chinese Artist and Taoist philosopher "If you do not change direction, you may end up where you are heading."