Code for sustainable homes Water efficiency and surface water runoff Jonathan Reed Atkins Water &...
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Transcript of Code for sustainable homes Water efficiency and surface water runoff Jonathan Reed Atkins Water &...
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Code for sustainable homes
Water efficiency and surface water runoff
Jonathan Reed
Atkins Water & Environment
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Introduction Atkins Water – why important? The Code objectives
Water efficiency Surface water runoff
Conclusions
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Atkins at a glanceWith a turnover of c.£1.2bn, Atkins is: One of the top 10 Best Big Companies to work for The largest engineering consultancy in the UK The largest multi-discipline consultancy in Europe The 4th largest design firm in the world Voted no.1 with ‘Best Reputation’ in Environment
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Water
“[water efficiency has] minimum standards that must be achieved at every level of the code, recognising [it’s] importance to the
sustainability of any home.”
Why? Water efficiency can be implemented now; Range of sustainability benefits – energy, environmental impacts,
etc. Improved adaptation to climate change.
Two areas covered by Code: Water efficiency Surface water run-off
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Water Efficiency
Weir Wood Reservoir in August 2005
Lowest recorded levels Increase in demand for
water should be minimised
Demand for water measured as a ‘Per Capita Consumption’, i.e. litres per head per day
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Surface water run-off and flooding
Impact of hard surfacing on run-off, infiltration and drainage
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Water Efficiency
Code Objectives
Predicted internal consumption
Points Awarded Required for code level
≤120 l/hd/d 1.5 1(), 2()
≤110 l/hd/d 3 -
≤105 l/hd/d 4.5 3(), 4()
≤90 l/hd/d 6 -
≤80 l/hd/d 7.5 5(), 6()
External consumption Points Awarded -
Rainwater collection and use (eg water butts)
1.5 -
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How water is used
Components of household water use for average days (WRc 2005)
Components of demand 2/3 of total consumption
through: Toilets Taps Showers
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Step 1 – minimise water use Toilets
Dual flush 6/4 litre Can be reduced further
Showers Flow rates of 6-9 l/min Aerating shower heads Flow restrictors
Baths Shaped baths
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Step 1 – minimise water use Taps
Aerated taps (downstairs sinks) Flow restrictors
Appliances Dishwashers Washing machines
External Fit a water butt
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Water Efficiency
Code Objectives
Predicted internal consumption
Points Awarded Required for code level
≤120 l/hd/d 1.5 1(), 2()
≤110 l/hd/d 3 -
≤105 l/hd/d 4.5 3(), 4()
≤90 l/hd/d 6 -
≤80 l/hd/d 7.5 5(), 6()
External consumption Points Awarded -
Rainwater collection and use (eg water butts)
1.5 -
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Step 2 – use of non potable water
Source Uses
Rainwater Roofs and hardstanding Toilet flushing, garden watering and vehicle washing
Greywater Wastewater from sinks, baths and showers
Toilet flushing and garden watering
Rainwater and greywater Risk assessment Secondary pipework system
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Surface water runoffNew development has two main impacts:
1 Increases runoff rates – making flooding worse elsewhere
2 Reduces volume available for floodwater in the floodplain
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Surface water run-off Code objectives
Reduction of surface water run-off Points Awarded Required for code level
Attenuation covering hard surfaces 0.5 1() Peak run-off and annual run-off volume no
greater than before development
Attenuation covering roofs 0.5
Flood risk Points Awarded -
Low annual probability of flooding 1 -
Medium/high annual probability of flooding. See code requirements.
0.5 -
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PPS25 – Development and flood risk Environment Agency are statutory
consultees Aims to minimise the risks of
development in flood risk areas Areas designated by the risk of
flooding
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Benefit of SUDS
Manages water at source and reduces peak flows Improves water quality Improves both visual and natural habitats
Hard surfacing
Natural runoff rate
Run
-off
Time
Run-off vs Time for storm event
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SUDS techniques
Permeable paving Allows water infiltration
Swales Flow attenuation and
conveyance
Green roofs Reduce run-off volume and
rate
Underground storage High density development
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Long term maintenance of SUDS Maintenance
Long term maintenance of SUDS needed
Who by? Sewerage undertaker Local Authority Highways Authority
How? Early consultation needed Sewers for Adoption Model agreements for
SUDS
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Conclusions
Water efficiency Water efficient appliances
Toilets and showers
Non potable use of water Rainwater or greywater for toilet flushing
Water butts
Surface water runoff SUDS to reduce and improve surface water runoff Flood risk controlled through links with PPS25
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Thank you