Some aspects of the energy-led retrofitting of solid wall dwellings

Transcription

1 Some aspects of the energy-led retrofitting of solid wall dwellings Phil Banfill, Sophie Simpson Heriot-Watt University, School of the Built Environment Ecobuild, March 2013

2 Structure of presentation Relationship between airtightness and mechanical ventilation with heat recovery (MVHR) Effect of the order of installing retrofit measures Resilience to climate change Used Dynamic Thermal Modelling on the E.On 2016 house

3 1. MVHR investigation Ducts in service void Inlet grilles at high level controllable Sensors in ducts - airflow, temp, rh Room sensors for CO 2, VOCs etc Why is it important? Air leakage is a waste of energy. MVHR recovers heat from extractor systems. Is promoted as a retrofit measure. Research questions: What is the relationship between air-tightness and MVHR energy saving? How difficult is achieving airtightness in retrofit? Can we use the results to model predicted performance?

4 MVHR workmanship problems

5 House sealing challenges

6 Modelled energy consumption with MVHR & ' % $ #! " 5 achieved in E.On House after a lot of work! (!$ ) * &+ '

7 ', * " $-, * " CO 2 emissions with MVHR 5 achieved in E.On House after a lot of work! (!$ ) * &+ '

8 2. The order of installing retrofit measures Affects choice of boiler Why is it important? May spread costs over a manageable timescale. Ease of implementation varies. Risk of incurring additional costs. Research questions: Does the sequence matter? Are measures equally effective whenever they are used? What are the effects on energy, CO 2 emissions and costs? Are there any implications for Green Deal?

9 The sequences investigated Improvement Stage 1. Insulation driven 2. Affordability driven 3. Experienced installer driven 1 CFL lighting CFL lighting Draught-proofing to stage 1 2 Loft insulation Loft insulation Double glazing 3 External wall insulation 4 Double glazing Ground floor insulation and initial draughtproofing Reduced size boiler replacement Reduced size boiler replacement Loft insulation 5 Ground floor insulation and initial draughtproofing Double glazing External wall insulation 6 Further draughtproofing & installation of MVHR External wall insulation Ground floor insulation and CFL lights 7 Reduced size boiler replacement Further draughtproofing & installation of MVHR Further draughtproofing & installation of MVHR

10 Effect on annual energy consumption CFL lights Base case Loft Insulation Draughtproofing Wall Insulation Double Glazing Efficient Boiler Ground floor insulation & sealing Efficient Boiler Loft Insulation Insulation Affordability Experienced installer Double glazing Double Glazing Ground floor insulation & sealing Draught-proof & MVHR Wall Insulation CFL lights & Ground floor insulation Wall Insulation Draught-proof & MVHR Draught-proof & MVHR Efficient boiler

11 Implications for Green Deal double glazing Improvement Stage Insulation driven Affordability driven Experienced installer driven 1 CFL lighting CFL lighting Draught-proofing 2 Loft insulation Loft insulation Double glazing 3 Wall insulation 4 Double glazing Ground floor insulation and sealing Efficient condensing boiler replacement 5 Double glazing Energy reduction attributable to improved glazing Annual Cost Savings (@4p/kWh for gas) 8.81 MWh 7.12 MWh 6.36 MWh

12 3. Climate change resilience Central estimate of increase in mean daily summer temp, 2050s (UKCP09) Why is it important? Retrofitting dwellings leads to concerns of overheating. Potential for householders to use cooling, increasing CO 2 emissions. Research question: What is the effect of future climate on overheating risk and energy consumption?

13 Future overheating in the E.On house

14 Comments As the climate warms: The E.On House uses less energy The internal temperatures rise The proportion of occupied hours at >25 C rises Bedroom temperatures are a potential problem with peaks up to 34 C Comfort depends on what is an acceptable risk of overheating

15 Key findings 1. MVHR systems can save energy and CO 2 but must be properly installed and balanced, and the house made sufficiently airtight. 2. Performance of retrofit programmes depends on the order in which measures are installed and this has implications for Green Deal finance. 3. Climate change has the potential to cause overheating in retrofitted homes.

16 Research outputs further reading 1. Banfill, P.F.G., Simpson, S.A., Gillott, M.C., White, J., Mechanical ventilation and heat recovery for low carbon retrofitting in dwellings, Proceedings of the World Renewable Energy Congress 2011, Linköping, Sweden, paper 0334, Banfill, P.F.G., Simpson, S., Gillott, M.C., White, J., The potential for energy saving in existing solid wall dwellings through mechanical ventilation and heat recovery, in Energy efficiency first: foundations of a low-carbon society, Proceedings of eceee 2011 Summer Study on energy efficiency, Belambra, Presqu'île de Giens, France, paper 6-031, Simpson, S.A., Banfill, P.F.G., The importance of the order of installation of retrofit measures in optimising long term energy and CO 2 reductions, Proceedings of Retrofit 2012 Academic Conference, Jan. 2012, University of Salford 4. Banfill, P.F.G., Simpson, S.A., Haines, V., Mallaband, R., "Energy-led retrofitting of solid wall dwellings: technical and user perspectives on airtightness", Structural Survey, 30 (3), (2012), (Also in RICS COBRA 2011 Conference, Salford.)

17 Thank You Phil Banfill, Sophie Simpson Heriot-Watt University, School of the Built Environment