BPE Case Study - Lyndhurst Crescent, Swindon

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1 Professor Rajat Gupta Oxford Institute for Sustainable Development, Oxford Brookes University BPE Case Study - Lyndhurst Crescent, Swindon Building Better Buildings Conference, Bristol 3 rd February 2016

2 Low Carbon Building Group BPE research portfolio BPE studies of domestic, non-domestic, (new-build and refurbishment) over 15 years. Flagship PGT module on POE: 12 years Case studies investigation of building performance to understand cause and effects. Period of investigation: construction stage through to in-use Socio-technical research using mixedmethods approach. Externally-funded research: Innovate UK Research Councils (EPSRC/ESRC) EU Horizon 2020 Industry earch/lowcarbonbuilding/

3 Involvement in Innovate UK BPE programme Funded by: Innovate UK Building Performance Evaluation programme Appointed by Innovate UK as building performance evaluator to provide technical advice and peer review at the project and programme level. Meta-study on characteristics and performance of MVHR systems (with Glasgow School of Art and Four Walls Ltd.)

4 Our new BPE research booklet summarises our research in this area. g-bpe-booklet-2015.pdf

5 Structure of presentation Context: case studies and methodology Findings from BPE study elements Assessment of fabric performance and services Handover procedures and user guidance Usability of controls Monitoring of actual energy use Monitoring of indoor environmental conditions Occupant feedback from interviews and surveys Wider lessons

6 Context: case study and methodology

7 Overview of BPE study To broaden our understanding of actual energy performance of low-carbon homes and close the feedback loop between design intent and outcome. Phase 1: Post-construction &Initial occupancy Nine-month study (2011) Capture as built performance of building envelope and compare it to as designed. Evaluate handover process. Map initial occupant reaction of occupants (amenity, comfort levels, understanding of systems). Phase 2: In-use & Post Occupancy evaluation Two year study ( ) Assess overall energy use and provision of comfort. Detailed analysis of usability, effectiveness and robustness of micro-generation.

8 BPE methodology Fabric testing Thermographic survey Air-tightness test Co-heating test U-value test Commissioning review of services and systems Commissioning checks of systems and services MVHR tests Review of handover process and occupant guidance

9 BPE methodology (Phase 2 BPE) Energy monitoring and assessment Smart metering and sub-metering DomEarm & benchmarking Monitoring of environmental conditions Temperature Relative Humidity CO 2 Levels Window opening Occupant studies Occupant satisfaction survey using BUS Interviews and walkthroughs with occupants Activity logging and thermal comfort diaries

10 Case study background Completed in March Owned by Swindon Borough Council Code Level 5 certification, SAP rating A Combination of optimized airtight building envelope and use of renewables Built in one construction phase by applying hempcrete cast into a timber frame.

11 Case study development: Lyndhurst Crescent 13 Code Level 5 houses for social rental in Swindon 1 end-terrace, 5bed, 9 persons 3 end-terrace, 3bed, 6 persons 3 mid-terrace, 3bed, 6 persons 6 mid terrace, 2bed, 4 persons

12 Case study homes Phase 1: House 6: mid-terrace, 3bed House 7: end-terrace, 3bed House 11 Phase 2: House 5: mid-terrace, 2bed House 11: mid-terrace, 2bed House 7 House 6 House 5

13 Case study homes Phase 1 Phase 2 House 6 House 7 House 5 House 11 Area m Typology No. of bedrooms 3storey, mid terrace 3storey, end terrace 3 bed 3 bed House 5 House 6 House 7 House 11 two-storey, mid terrace 2 bed (One adult & two children, 24h occupancy) two-storey, mid terrace 2 bed (Two adults & two children, 24h occupancy)

14 Construction details & design performance Main construction elements Design U-value W/m 2 K Ground Floor Screed over insulation on beam and block 0.12 Roof Tile on timber 0.15 Walls Rendered hempcrete cast into timber frame 0.18 Windows Timber frame, double glazing, low-e 1.4 External door Wooden 1.6

15 Services & specifications Main heating Heating controls Hot water Solar water heating Ventilation Renewables NIBE Fighter heat pump air-to-water. Heat pump load or weather compensation. Underfloor heating coils Time and temperature zone control From primary heating system. Immersion present Nu-Heat solar panel. South oriented Mechanical extract from kitchen and bathroom, fresh air supply in other rooms, connected to the ASHP. 4kWp photovoltaics Target air tightness (m 3 /hm 2

16 Findings from the BPE study: Fabric tests, services and systems

17 Air permeability tests Measured AP values were well above the design target of 2m 3 /h.m 2 suggesting heat losses due to air leakage paths. Air leakage paths were revealed behind / below various skirting boards, windows, electrical cupboards. House 11: Air-permeability did not meet UK Building Regulation (10m 3 /h.m 2 ) Phase 1 (2011) Phase 2 (2013)

18 Thermal Imaging Air leakage through door and window frames, window sills. Heat loss through exposed wall Cold spot identified on wall. Air leakage around door frames. Thermal bridging across threshold. Air leakage through window frame

19 Review of commissioning At the time of the inspection, the installed systems remained to be finally commissioned. Exhaust air heat pump (EAHP) and heating system were not fully commissioned. EAHP fan speed set very high. Underfloor heating system out of operation on the first floor and related control circuit disconnected. Uninsulated primary heating pipework. Use of MVHR system during sanding activities resulted in highly contaminated filters with dust particles.

20 MVHR testing Methodology The airflow of all extract and vents were measured in both houses. Measurements were taken on 2 nd July 2013 for House 5 and on 16 April 2013 for House 11. Findings The tests revealed great discrepancy between the supply and extract rates. Extract rates House 5 House 11 Low rate (l/s) High rate (l/s) Low rate (l/s) High rate (l/s) Supply rates Supply & extract rates balance ratio % %

21 Review of control interfaces Heating room thermostat had oversimplified arbitrary line scale without labelling or numbering. Red light indicating whole system operation rather than room status. Masterstat without indication of system response (no light, sound, temperature indication). Room and master thermostats had significantly different displays and approaches. Not clear annotation. User needed to experiment. Room thermostat Usability criteria Ranking Poor Excellent Clarity of purpose Intuitive switching Labeling and annotation Ease of use Indication of system response Degree of fine control

22 Design team interview and handover Weak communication between contractor, and specialists and poor feedback to design team. Hempcrete drying delayed the handover process and affected appearance of external walls. Inexperience of local contractor hindered delivery of the innovative design expectations. Handover was graduated but home user guide was not ready during the induction tour, resulting in inadequate user knowledge concerning systems operation and control.

23 Energy monitoring & assessment

24 Total electricity use (Sept 2013-Aug 2014)

25 Total carbon emissions (Sept 2013-Aug 2014) Carbon factor (kgco 2 ) Electricity: Gas: 0.198

26 Annual energy costs (Sept 2013-Aug 2014) Cost estimated as p /kwh

27 Breakdown of energy by end-use Energy by end uses (kwh/m 2 /annum) Design estimate (SAP) 32% unregulated House 5 House 11 35% unregulated SAP tends to underestimate heating and hot water loads (REGULATED) & does not take into account cooking and appliances use (UNREGULATED) Design estimate (SAP) 21% unregulated Case C1 Design estimate (SAP) 22% unregulated Case C Space Heating Hot Water Fans and Pumps Lighting Cooking Electronics Refrigeration Wet appliances Small power Other

28 Heat pump efficiency: Degree days Heat pump electricity use in House 11 follows temperature variations more closely, resulting in more efficient performance. Baseload heat pump electricity use for hot water: House 5 (300kWh), House 11(200kWh)

29 Environmental monitoring and feedback from occupants

30 Living room temperatures (Min, mean, max) House 11 generally 1-2 o C cooler than House 5. Temperatures in House 11 more variable due to different air-permeability levels and heating patterns Temperatures within comfort levels. House 11 cooler in summer due to high air-permeability levels.

31 Internal temperature distribution House 5 Living room: 30% of the time temperatures range between o C, and 2% of the time they range between o C. Bedrooms: 75% of the time temperatures range between o C, 13% of the time they range between o C and 2% of the time they range between o C. House 11 Living room: 14% of the time temperatures range between o C, and 3.3% of the time they range between o C. Bedrooms: 27% of the time temperatures range between o C, 16% of the time they range between o C.

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33 Indoor CO 2 concentration House 5 Living room: 72% of the time CO 2 levels range between ppm, and 2.5% of the time they range between ppm. South bedroom: 78% of the time CO 2 levels range between ppm, 3.8% of the time they range between ppm. House 11 Living room: 83% of the time CO 2 levels range between ppm, and 1.6% of the time they range between ppm. North Bedroom: 75% of the time CO 2 levels range between ppm, 15.6% of the time they range between ppm.

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35 BUS survey Respondents feel facilities provided meet their needs well. Lighting level overall is one of the most appreciated aspects of the dwellings. Temperatures during winter are generally regarded as quite comfortable. Summer temperatures are regarded as less comfortable. Air quality is considered to be quite satisfactory during summer but less so during winter.

36 Feedback from occupants Energy and water consumption High electricity bills. Not satisfied with heat pump performance Occupant satisfaction House 5: not pleased with open plan kitchen and appearance House 11: very pleased with the design, layout and overall appearance Ventilation system (mechanical ventilation and heat recovery) Not sufficient training on operation of MVHR Noise and draughts coming from MVHR. Heating system Confusion about daily/seasonal operation of heat pump. House 5: complained for having little control over heating. Not sufficient guidance during the induction. No direct instructions in Home User Guide about operation of heating system. Home User Guide & Induction process Home User Guide very long and hard to understand Information included in the guide was not always accurate

37 Wider lessons

38 Wider lessons Modelling tools: When modelling building energy use at the design stage, potential issues of underperformance and occupant behaviour need to be considered, otherwise there is a risk of under-estimating energy use. Documentation: As built energy models (and commissioning records) should be enforced to check if dwellings are built as designed, and any changes in design or procurement are captured. Detailing: Careful detailing (robust details) to avoid thermal bridging and achieve designed air-permeability rates. Rapid diagnostics onsite and better communication between design team, builder and sub-contractors is required given the interdependencies in building performance. Commissioning: Seasonal commissioning needs to be encouraged for technologies such as heat pumps and MVHR systems.

39 Wider lessons Ventilation strategies: MVHR was adopted for achieving a high code compliance without considering the expectations and habits of occupants. Balance between air-tightness and ventilation should be achieved otherwise indoor air quality may get compromised. Guidance and training: Simple and clear guidance and handover procedures on seasonal operation tailored to the needs of occupants (gender, age, technical ability) Control interfaces: Usability of control interfaces influence occupant interaction. Controls to be accessible and clearly labelled with an indication of system response that is rapid and detectable. Building monitoring: Retrofitting monitoring kit is neither particularly easy nor cheap. Building designers should design in monitoring kit into building space anticipation of BPE studies. Monitoring kit should be integrated within low carbon technologies. Benefit of BPE: Without the BPE study, many of these problems would have gone un-noticed and developed into serious issues. Feedback loops are vital for continuous learning and improvement.

40 Thank you!