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NZEB: Regulatory impact assessment for part l dwellings

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David Ross, AECOM presents on the regulatory Impact Assessment for Part L dwellings at the SEAI Energy SHow, April 2018.

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NZEB: Regulatory impact assessment for part l dwellings

  1. 1. Regulatory Impact Assessment for Part L Dwellings David Ross, AECOM 18 April 2018
  2. 2. Project Scope DHPLG appointed AECOM and Currie and Brown to carry out the following : – Energy and carbon performance modelling for 5 typical new dwellings constructed to NZEB performance levels – Identify the uplift in capital cost for NZEB performance – Assess any associated overheating risk – Review the performance of renewable energy systems in multi- storey apartment blocks – (Identify the additional capital cost of major renovations to a cost optimal level as required under EPBD)
  3. 3. Definition of NZEB The European Energy Performance of Buildings Directive has the following definition: – “a building that has a very high energy performance…. The nearly zero or very low amount of energy required should be covered to a very significant extent by energy from renewable sources including energy from renewable sources produced on- site or nearby”
  4. 4. Definition of NZEB DHPLG has the more explicit definition: – Maximum Energy Performance Coefficient of 0.30 – Maximum Carbon Performance Coefficient of 0.35 – Minimum Renewable Energy Ratio of 0.20
  5. 5. Specifications to meet NZEB: Dwelling types Building Category Building Type Floor Area Single Family Buildings Semi-Detached House 126 m2 Detached House 160 m2 Bungalow 104 m2 Apartment Block Mid-Floor Flat 80 m2 Top-Floor Flat 80 m2
  6. 6. Specifications to meet NZEB: Fabric and Services Elements Proposed Part L 2018 specification External Wall U-value 0.13 Floor U-value 0.14 Roof U-value 0.11 Windows U-value 0.9 (Triple glazed) Thermal Bridging Y-value 0.05 Air Permeability 5 Ventilation strategy Natural ventilation (or cMEV at 3m3/m2/hr) Heating system 91.3% mains gas condensing gas boiler Controls Boiler interlock Time and temperature zone control Hot water demand 1 shower with 6 litres/min flow restrictor 1 Bath No electric showers Overall target of 125 litres/person/day Hot water cylinder 120 litres, 100mm factory insulated Lighting 100% low energy lighting: · A+ Rated Bulbs, 94 lumen/cW, 4 W/m2
  7. 7. Specifications to meet NZEB: Renewables (Semi) Heating and Ventilation PV (kWp) PV (% roof area) EPC CPC RER Gas Boiler NV 1.15 7% 0.30 0.28 0.22 Gas Boiler MVHR + AP of 3 0.85 5% 0.26 0.24 0.20 Heat Pump NV 0 0% 0.25 0.21 0.42 Heat Pump MVHR + AP of 3 0 0% 0.25 0.20 0.33 MVHR: SFP = 0.8 W/l/s, HR = 85% HP: Individual air to water, underfloor heating, SH =400%, DHW = 200%
  8. 8. Specifications to meet NZEB: Renewables (Mid-flat) Heating and Ventilation PV (kWp) PV (% roof area) EPC CPC RER Gas Boiler NV 0.85 8% 0.30 0.29 0.27 Gas Boiler MVHR + AP of 3 0.55 5% 0.27 0.26 0.20 Heat Pump NV 0 0% 0.29 0.25 0.37 Heat Pump MVHR + AP of 3 0 0% 0.29 0.25 0.29
  9. 9. Uplift in capital cost to meet NZEB Currie and Brown provided 2017 Dublin Cost data – Internal cost database (live projects they are supporting) – Cross-checked with peers who have independent experience of the Irish construction market – Cross-referenced with a third party database in the Irish market Uplift against TGD 2011 – Based on Appendix E of TGD 2011 – Amount of PV varying by building type
  10. 10. Uplift in capital cost (depending on compliant solution) Building Type Additional CAPEX (€/m2) Additional CAPEX (%) Semi-Detached House 12 to 39 0.9 to 2.9 Detached House 13 to 49 1.0 to 3.5 Bungalow 14 to 65 1.0 to 4.2 Top-Floor Flat 13 to 49 0.7 to 2.9 Mid-Floor Flat 8 to 49 0.5 to 2.9 – NZEB can be achieved ~0.5-1.0% uplift of current CAPEX – Lowest cost solutions: PV or HP alone (CAPEX associated with move to triple glazing & LZCs) – Higher cost solutions: SHW or adding cMEV/MVHR
  11. 11. Assess overheating risk Apply new CIBSE TM59 modelling methodology and criteria to assess residential overheating – Criterion A (living rooms, kitchens & bedrooms) Internal temperature should not exceed a defined comfort temperature by 1°C or more for more than 3% of occupied hours over the summer period (May to Sept) – Criterion B (bedrooms) The internal temperature between 10 pm and 7 am should not exceed 26°C for more than 1% of annual hours
  12. 12. Assess overheating risk – Undertook IES thermal modelling • Five dwelling forms • Manchester 2020s DSY1 weather file (Dublin data TBC) • TM59 methodology occupancy profile, heat gains etc – Occupants: • Detached house: 4 bed 8 person • Semi-detached house: 3 bed 5 person • Bungalow: 3 bed 6 person • Apartments: 2 bed 4 people – Daytime occupancy assumed in all cases
  13. 13. Assess overheating risk – Windows start to open in occupied rooms when indoor (operative) temperature > 22C and fully open when temperature > 26C. Reverse occurs at temperatures fall. – Internal doors open all the time, with the exception of bedroom doors which are closed overnight – Windows: g-value = 0.6 (triple glazed, low E, soft coat) – Orientation • Living rooms face west. Apartments assumed west and south • No external shading or internal blinds/ curtains assumed for base-case
  14. 14. Assess overheating risk – Risk mitigation sufficient where dwelling overheated • Occupant controlled curtain/ blinds drawn on the east, west and/or south façades when incident solar radiation • Incident radiation to lower shade - 200 W/m2 • Incident radiation to raise shade - 150 W/m2
  15. 15. Assess overheating risk: Before any mitigation Building Type Room TM59 Criteria A TM59 Criteria B % hours exceeded Pass/Fail % hours exceeded Pass/Fail Semi Detached Living Room 2.8% Pass - - Bedroom 1 1.6% Pass 0.58% Pass Bedroom 2 1.0% Pass 0.55% Pass Bedroom 3 3.5% Fail 0.79% Pass Detached Living Room 2.7% Pass - - Bedroom 1 1.4% Pass 0.94% Pass Bedroom 2 1.4% Pass 0.91% Pass Bedroom 3 1.8% Pass 0.85% Pass Bedroom 4 1.8% Pass 0.88% Pass Bungalow Living Room 3.4% Fail - - Bedroom 1 0.8% Pass 0.52% Pass Bedroom 2 2.0% Pass 0.85% Pass Bedroom 3 2.2% Pass 0.85% Pass Top Floor Apartment Liv / Kitchen 3.3% Fail - - Bedroom 1 0.7% Pass 0.49% Pass Bedroom 2 1.1% Pass 0.55% Pass Mid Floor Apartment Liv/ Kitchen 4.1% Fail - - Bedroom 1 0.9% Pass 0.64% Pass Bedroom 2 1.4% Pass 0.70% Pass
  16. 16. Renewable energy systems in apartment blocks – Evaluate ability of city apartment block to meet RER of 20% • Two apartment blocks: 6 & 14 stories (12 units per floor) • Heat pumps or PVs (roof only) – To work out the maximum available roof area for PVs: • 70% of roof area available for PV, after services and over- shading • 20% allowance for spacing between panels and access. • Net maximum available area of 56% of the total roof area.
  17. 17. Renewable energy systems in apartment blocks – Results showed • gas boilers and PVs feasible to 12 stories • Heat pumps feasible for all heights Ventilation Package Heating Package kWp per apartment EPC CPC RER Comply Natural ventilation Gas boiler 0.50 0.33 0.31 0.16 No Natural ventilation Heat pump - 0.28 0.24 0.37 Yes MVHR Gas boiler 0.50 0.28 0.26 0.18 No MVHR Heat pump - 0.28 0.24 0.29 Yes Results for 14 storey apartment block
  18. 18. – The dwelling types achieved compliance with proposed NZEB specification using different design solutions. – Average cost uplift across dwellings was 1.9%. Range of 0.5% to 4.2% depending on dwelling and design solution. – Overheating analysis indicated a relatively small overheating risk based on the new CIBSE TM59. The mitigation package was fairly limited to occupant controlled curtain/ blinds. – Heat pumps are feasible solution to meet RER on all apartment blocks. PV is feasible for the apartment block modelled up to 12 storeys in height. Conclusions
  19. 19. Thank You

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