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Is zero carbon possible?

Is zero carbon possible?. Nick Jones Low Carbon Housing Team, BRE. The nine sustainability ‘elements’. Energy / CO 2 Potable water Surface water runoff Materials Construction site waste / household waste Pollution Health and wellbeing Management Ecology.

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Is zero carbon possible?

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  1. Is zero carbon possible? Nick Jones Low Carbon Housing Team, BRE

  2. The nine sustainability ‘elements’ • Energy / CO2 • Potable water • Surface water runoff • Materials • Construction site waste / household waste • Pollution • Health and wellbeing • Management • Ecology

  3. Energy – mandatory requirements

  4. HM Treasury • Stamp duty relief on newbuild zero carbon homes starting now • Pump-priming for full ‘zero carbon’ • Essentially use the Level 6 definition • Joined-up thinking?!

  5. We’re very excited – but who is most excited?

  6. Going forward - Passivhaus • European voluntary standard, approx. CSH Level 4 - 5 • www.Passivhaus.org.uk managed by BRE • Typical U-values 0.15 (opaque), 0.8 (windows) • Airtight - 1.0 m3/m2hr @ 50Pa • Efficient MVHR (80%) • Minimal thermal bridging • Attention to solar layout • 15kWh/m2yr space heating demand • 120kWh/m2yr total primary energy use • Usually a ‘post-heater’ is sufficient, with solar DHW • Often electric – but not in UK (carbon intensity of generation mix)

  7. Energy v. carbon • Gas – 0.194 kg/kWh • LPG – 0.234 kg/kWh • Oil – 0.265 kg/kWh • Electricity from grid – 0.422 kg/kWh? • Displaced electricity – 0.568 kg/kWh? • Biomass – 0.025 kg/kWh

  8. The future:‘zero carbon’ homes It gets much harder! Every available point matters. Two critical decisions… • Precisely which carbon emissions are to be zero? • Exactly what do we mean by ‘zero’?

  9. Q1. Precisely which carbon emissions must be zero? • Space heating, water heating and lighting: level 5 • Everything, including cooking and domestic appliances too: level 6

  10. Q2. Exactly what do we mean by ‘zero’? • zero carbon: “no carbon-emitting fuels are burnt on site, and we do not import any electricity from the grid” • net zero carbon: “we do burn carbon-emitting fuels on site but we export, to the grid, locally-generated renewable electricity to make up for it” • carbon neutral: “we import, via the grid, remotely-generated ‘additional’ renewable electricity”

  11. No room for complacency… • Typical new mid-terrace but with ‘extreme’ spec… • U = 0.1 all round • Air permeability = 1 m3/ m2hr • Biomass community heating system • Strategy #1: use individual PVs • To reach L5 would need approx 1 kWpof PVs per dwelling • To reach L6 would need approx 2.5 kWp of PVs per dwelling • Clearly compromised by increased housing densities • Strategy #2: use single turbine for small sites • To reach L5 would need a 20kW turbine • To reach L6 – big!

  12. Off-site generation then? • Current thinking is that you must get to Level 5 solely by on-site means (albeit including renewable electricity export if desired)… • …and only then are you allowed to include off-site measures in order to get to Level 6 • In both cases you must max the fabric first, and heat-dumping is disallowed

  13. Today’s picture • 1 house assessed to 100% improvement on DER • 1 house assessed to ‘zero carbon’

  14. What’s needed • Onsite renewables – planning, markets, training. • Offsite renewables – planning, accreditation. • Construction detailing – knowledge, training and practice. • Air leakage – knowledge, training and practice. • Energy networks – Massive investment – who pays, change of thinking? • External appearance – planning Will we be building houses people want to live in?

  15. Winning Design: GREEN HOUSEArchitect: Gaunt Francis Architects

  16. Food for thought… • Must forbid conventional ‘green tariffs’ (28-day rule; not usually ‘additional’) • Over-optimistic claims for devices – certification scheme? • Biomass fuel supply? • Private wire/heat-main networks at the site level - relatively rare in the UK • ‘Development’ becomes infrastructure provision, not housebuilding? • Downstream involvement by housebuilders with their purchasers - ESCOs? Leaseholds? Legal agreement to accept a particular energy supply? – unprecedented • Certification of renewable electricity imports – REGO? Additionality? • Larger vs. smaller developers – build own windfarms? New trading scheme?

  17. Is zero carbon possible? Nick Jones Low Carbon Housing Team, BRE

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