Code for sustainable homes Water efficiency and surface water runoff Jonathan Reed Atkins Water & Environment

Introduction Atkins Water – why important? The Code objectives Water efficiency Surface water runoff Conclusions

Atkins at a glance With 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 4 th largest design firm in the world Voted no.1 with Best Reputation in Environment

Water [water efficiency has] minimum standards that must be achieved at every level of the code, recognising [its] 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

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

Surface water run-off and flooding Impact of hard surfacing on run-off, infiltration and drainage

Water Efficiency Code Objectives Predicted internal consumption Points Awarded Required for code level 120 l/hd/d1.5 1( ), 2( ) 110 l/hd/d l/hd/d4.5 3( ), 4( ) 90 l/hd/d6- 80 l/hd/d7.5 5( ), 6( ) External consumptionPoints Awarded- Rainwater collection and use (eg water butts) 1.5-

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

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

Step 1 – minimise water use Taps Aerated taps (downstairs sinks) Flow restrictors Appliances Dishwashers Washing machines External Fit a water butt

Water Efficiency Code Objectives Predicted internal consumption Points Awarded Required for code level 120 l/hd/d1.5 1( ), 2( ) 110 l/hd/d l/hd/d4.5 3( ), 4( ) 90 l/hd/d6- 80 l/hd/d7.5 5( ), 6( ) External consumptionPoints Awarded- Rainwater collection and use (eg water butts) 1.5-

Step 2 – use of non potable water SourceUses RainwaterRoofs and hardstanding Toilet flushing, garden watering and vehicle washing GreywaterWastewater from sinks, baths and showers Toilet flushing and garden watering Rainwater and greywater Risk assessment Secondary pipework system

Surface water runoff New development has two main impacts: 1 Increases runoff rates – making flooding worse elsewhere 2 Reduces volume available for floodwater in the floodplain

Surface water run-off Code objectives Reduction of surface water run-offPoints AwardedRequired for code level Attenuation covering hard surfaces0.5 1( ) Peak run-off and annual run-off volume no greater than before development Attenuation covering roofs0.5 Flood riskPoints Awarded- Low annual probability of flooding1- Medium/high annual probability of flooding. See code requirements. 0.5-

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

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

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

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

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

Thank you