New Challenges in Energy Efficiency in Buildings

Broadland Housing Forum 12th September May 2007 CRed Carbon Reduction Keith Tovey(杜伟贤)MA, PhD, CEng, MICE, CEnv New Challenges in Energy Efficiency in Buildings Energy Science Director HSBC Director of Low Carbon Innovation CRed Acknowledgements: Karla Alcantar, Charlotte Turner

New Challenges in Energy Efficiency in Buildings • Background • Background • Energy Efficiency and Sustainable Building Construction • Thermal Performance • Future Proofing Buildings - Fabric Cooling? • Renewable Energy • Life Cycle analyses • Integration of Design • Functional Energy Use • Management of Building Energy Use • Behaviour of the Occupants • Conclusions

Changes in Temperature

New Challenges in Energy Efficiency in Buildings • Background • Energy Efficiency and Sustainable Building Construction • Thermal Performance issues • Future Proofing Buildings - Fabric Cooling? • Renewable Energy and Integration of Design • Life Cycle issues • Management of Building Energy Use • Behaviour of the Occupants • Conclusions

Thermal Performance Issues: Future Proofing • Thermal performance has improved with better insulation. • With better fabric insulation, ventilation can represent up to 80+% of heating energy requirements. • Careful design of ventilation is needed • lower capital costs vs lower environmental running costs. • Are ESCO’s a way forward? • Provide optional environmentally efficient systems within all new buildings. • Improved control – Smart (Sub) Metering • Is traditional Cost Benefit Analysis the correct way to appraise low carbon systems? • Issues of overheating need to be addressed

Sustainability in Building and Occupation Index 1960 = 100 Impact of Changing Climate Changes in heating and cooling requirements for buildings over last 50 years Heating requirements are ~10+% less than in 1960 Cooling requirements are 75% higher than in 1960. Care must now be taken to ensure buildings are now designed to avoid overheating in summer and to minimise active cooling requirements

Fabric Cooling using Hollow Core Slabs Cold air Cools the slabs to act as a cool store the following day Cold air 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 Draws out the heat accumulated during the day Summer night night ventilation/ free cooling

Fabric Cooling using Hollow Core Slabs Warm air Warm air 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 Pre-cools the air before entering the occupied space No air conditioning is needed even though the norm would have been to install air-conditioning Summer day The concrete absorbs and stores the heat – like a radiator in reverse In future, with Global Warming, when air-conditioners may be installed, they will be run over night to pre-cool building and improve efficiency of chillers

Heat Pumps: A solution for a Low Carbon Future • Ground Source Heat Pumps are an effective route to low carbon heating – can save 50 – 60% of carbon emissions. • Work most efficiently with under floor heating. • Can be used with fabric pre-cooling in summer with very modest air-conditioning • Can be to provide some inter-seasonal heat store • i.e. reject heat in summer to acquifer/ground – recover during winter. There is ~ 3 months thermal lag in peak temperature in ground corresponding with early heating season use, and much improved coefficients of performance.

Thermal Properties of Buildings • 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 Data collected 10th December 2006 – April 29th 2007

Options for Renewable Energy: Solar Thermal Solar Collectors installed 27th January 2004 Annual Solar Gain 910 kWh

Options for Renewable Energy: Solar Thermal • Performance of a solar collector 9th December 2006 – 3rd September 2007 • Average gain (over 3 years) is 2.245 kWh per day • Boiler rarely used to provide Hot Water from Easter to ~ 1st October • More Hot Water used – the greater amount of solar energy is gained • Optimum orientation for solar hot water collectors for most houses is NOT due • South

Options for Renewable Energy: Solar Thermal • Significant surplus of energy in summer • Explore increasing temperature limit • provided there is an anti-scald device fitted. • Training needed to educate users to get optimum from solar collector in mid- • season (setting of Central Heating Hot Water timers) • Energy/Carbon benefits to be gained by providing solar hot water on a multi- • house basis.

Options for Renewable Energy: Solar Photovoltaic

ZICER Building • 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 Photo shows only part of top Floor

Options for Renewable Energy: Solar Photovoltaic Arrangement of Cells on Facade Individual cells are connected horizontally If individual cells are connected vertically, only those cells actually in shadow are affected. As shadow covers one column all cells are inactive

Options for Renewable Energy: Solar Photovoltaic Peak output is 34 kW 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

Options for Low Carbon Technologies: Micro CHP • Potential to substantially reduce CO2 emissions • Significant reduction is losses from transmission • but • problem of heat disposal in summer • Does not make sense to provide CHP with solar hot water heaters • Consider using absorption chilling to provide cooling where required

Sustainability in Building and Occupation • Life Cycle Issues – an issue in Sustainability • Does local sourcing of materials necessarily lead to a low carbon construction? • In case of PV it emits LESS CO2 if cells are manufactured in Spain and transported to UK! • despite the transport!!!! • Need to be aware of how fuel mix used for generation of electricity affects CO2. • UK ~ 0.52 kg/kWh, Spain ~ 0.46 kg/kWh • France ~ 0.077 kg/kWh • To what extent does embodied carbon from construction and demolition affect total carbon emission? • Example: ZICER Building

Life Cycle Energy Requirements of ZICER as built compared to other heating/cooling strategies Naturally Ventilated 221508GJ Air Conditioned 384967GJ Heavy Weight As Built 209441GJ Materials Production Materials Transport On site construction energy Workforce Transport Intrinsic Heating / Cooling energy Functional Energy Refurbishment Energy Demolition Energy 28% 54% 34% 51% 29% 61%

Comparison of Life Cycle Energy Requirements of ZICER Comparisons assume identical size, shape and orientation Compared to the Air-conditioned office, ZICER recovers extra energy required in construction in under 1 year.

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.

Conservation: management improvements – User Satisfaction thermal comfort +28% air quality +36% lighting +25% noise +26% Careful Monitoring and Analysis can reduce energy consumption. A Low Energy Building is also a better place to work in

Good Management has reduced Energy Requirements 800 350 The space heating consumption has reduced by 57% Acknowledgement: Charlotte Turner

Electricity Consumption Average Norwich • 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 Data from 114 houses in Norwich

Personal Attitudes to Energy Use can be significant

Social Awareness of Occupational Impact on Climate Change

Conclusions Sustainable Buildings require: • Initial sound design addressing: high insulation standards, effective control of ventilation: Attention to Future Proofing. • Integration of use of building with provision of services. • Avoidance of combining novel technologies which are incompatible. • Use of most sustainable materials: Local provision of materials is NOT ALWAYS best – careful Life Cycle Assessments are needed. • Provision of optional extras for all buildings including renewable technologies etc perhaps with alternative financing methods. • Provision of SMART sub metering to inform the user. • Improvements in training of users where newer technologies are used. • a need for awareness raising. "If you do not change direction, you may end up where you are heading." LaoTzu (604-531 BC) Chinese Artist and Taoist philosopher

New Challenges in Energy Efficiency in Buildings