Presentation on theme: "Zero Carbon: Implications and Issues"— Presentation transcript:
1Zero Carbon: Implications and Issues Malcolm BellBuildings, Energy and Sustainability Group, School of the Built Environment, Leeds Metropolitan University, Leeds, UK.Paper presented to: Towards Zero Carbon Homes5 July 2007, Milton Keynes, UK.
8Passive House Standards Timber frame scheme Göteborg, Sweden (120 m2)Airtightness 1 m/hSource: Wall (2006), Photo: Hans EekMVHR – 80% with duct heaters5m2 Solar water + resistance top-up
9Passive House Standards Timber frame scheme Göteborg, Sweden, 120 m25,868 kWh6,420 kWhSource: Wall (2006), Photo: Hans EekTER (kgCO2/m2)Design ≈ 10.6Actual ≈ 15.3Under Swedish conditions!Total energy = 8,160 kWh/aSource: Wall (2006), Energy and Buildings. 38, pp
10Implications and issues Lights and appliances represent between 60% and 70% of carbon emissions.Over 5,000 kWh/a may need to be generated by zero carbon sources. (more for larger houses)What chance at the level of the dwelling?
15Micro wind? Manufacturer’s general claims: 1.5 kW (max at 12.5 m/s) Annual energy generated - 2, ,000 kWhs – depending on position and location.Carbon displacement – 1.3 tonnes (30% utilisation)Location:Average wind speed (DTI database) = mEnergy – 1,473 kWhsBut what about shelter from trees and other buildings?
22So what, so far ? Site based generation is problematic. Solar thermal - useful demand reductionWind is likely to be cheaper and more effective at large scaleBiomass may have limited value in CHP but no panacea and an important strategic resourceNeed to link new building to strategic renewable provision.
23So what for the industry? Source: Wall (2006), Photo: Hans EekFocus attention on as low an energy/carbon demand as possibleDeal with generation in a strategic way
24Does new housing do what it says on the tin? But!Does new housing do what it says on the tin?
25Notional – v – Real heat loss Plot No.Predicted Fabric Heat Loss (W/K)Predicted Ventilation Heat Loss (W/K)Predicted Total Heat Loss (W/K)Measured Heat Loss (W/K)Measured Heat Loss - Adjusted for Solar Gain (W/K)1350.613.263.8105.4111.740254.920.375.2136.3153.4+75%+104%The question is: Why?
34Understanding complex heat loss paths Party wall heat bypass
35Potential CO2 savings 18,000 tCO2/a Fabric heat loss is between 40% and 50% greater than currently estimated. Eliminating the bypass would produce large actual CO2 savingsFrom New Housing built in One Year (~190,000 units)18,000 tCO2/aFrom Existing Stock (built between 1965 and 2006)694,000 tCO2/aAssumes Party Wall U Value = 0.5Assumes 10% semi, 20% terrace in stock and new buildCalculations for semis and terraces only – no estimate for apartments
36We have been rumbled!As very low and zero carbon becomes mandatory small things will matterThis time customers will notice!This time building control will notice!We cannot hide behind flawed assumptions
37The industry must change! It has been said beforeBut the more it changes the more it remains the sameOld problems persist!It is time to retool, to retool cultures and processes as well as technology.
38What will change look like? A fully managed process – inception, design, construction and support in use.Performance will have to be guaranteed.A quality control process based on measurement not assumptionRe-engineering of processes as well as technology will bring economies!Constant feedback will bring constant improvement.