Draft PUSH Sustainable Development SPD

WATER

Draft PUSH Sustainable Development SPD

Resource Document

Introduction

Water

Energy/CO2

Materials and Waste

Health and Wellbeing

Green Roofs

Sustainable Management

Infrastructure and Major Developments

April 2009

WATER

Resource Document Contents

THI
S VOLUME / Volume / Chapter / Chapter title
Introduction / 1 / Introduction to this Guidance
1.1. / Purpose of this Resource Document
1.2 / Scope of this Resource Document
1.3. / Government Policy
1.4 / South East Plan Policies
1.5. / PUSH Planning Policy Framework
1.6. / The Council Core Strategy Policies
1.7. / How to use thisResource Document
2 / Sustainable Development: General
2.1 / National Policy Drivers
2.2 / Evidence Base in South Hampshire
2.3 / Design and Access Statements
2.4 / Code FSH and BREEAM
2.5 / Sustainability Checklist
THIS VOLUME / Water / 3
3.i / Introduction to Water
3.1 / Water Appliances
3.2 / Rainwater Harvesting
3.3 / Grey Water Recycling
3.4 / External Potable Water
3.5 / Reduction in Surface Water Runoff
3.6 / Flood Risk
3.7 / Adaptation to Climate Change
Energy/CO2 / 4
4.i / Introduction to Energy/CO2
4.1 / Natural Daylight
4.2 / Passive Solar Heat Gain
4.3 / Natural Ventilation
4.4 / Drying Space
4.5 / Energy Efficiency
4.6 / External Lighting
4.7 / Small Scale Zero/Low Carbon Technologies
4.8 / Zero Carbon Residential Developments
Materials and Waste / 5
5.i / Introduction to materials and waste
5.1 / Construction Waste
5.2 / Construction Materials
5.3 / Waste Recycling
5.4 / Composting
Health and Wellbeing / 6
6.i / Introduction to Health and Wellbeing
6.1 / Biodiversity
6.2 / Noise
6.3 / Private Space
6.4 / Lifetime Homes
6.5 / Pollution
6.7 / Accessibility
6.8 / Residential Density
6.9 / Security
Green Roofs / 7
7.i / Introduction to Green Roofs
7.1 / Green Roofs
Sustainable Management / 8
8.i / Introduction to Sustainable Management
8.1 / Building User Guides
8.2 / Considerate Constructors Scheme
8.3 / Construction Site Impacts
Infrastructure and Major Developments / 9
9.i / Introduction to Infrastructure and Major Developments
9.1 / Waste Management Infrastructure
9.2 / Green Infrastructure
9.3 / Large Scale Renewable Energy
9.4 / Major developments
Appendices
A / Model Essential Requirements
B / Sustainability Checklist

WATER

3.Water

3.i.Introduction to Water

This chapter looks at two aspects of water management:

1the use of potable water (i.e. treated water from the tap), with the aim to reduce its use both in the home and in non-residential buildings as well as in associated outdoor spaces.

2the way in which we manage rainfall in new development, identifying ways to reduce surface-water run-off in new development and reduce flood risk.

Potable Water

Water is becoming increasingly scarce as demand continues to increase dramatically. Over the last 30 years water consumption in the UK has risen by 70%. The average domestic water consumption is approximately 160 litres/person/day (150 l/p/day for new dwellings). There are many actions that can be taken to minimise water consumption and all should be considered. Sanitary use of water within a dwelling is significant and a number of steps can be taken to minimise consumption.Water-saving/efficient devices and appliances are just as economical to install into an existing building as they are at the initial construction phase.

Once all the possible water efficient appliances have been fitted, further significant efficiencies can be attained through recycling of rainwater and ‘greywater’. Sustainable Drainage Systems (SUDS) help to minimise the unnecessary loss of water to the mains drainage system and also reduce the likelihood of damaging and polluting flash floods.

Measures for rainwater harvesting, greywater drainage and SuDS are more economical to install during the construction phase than as part of a retro-fitting scheme, particularly in domestic situations.

Typical domestic water consumption (Source: Mid Kent Water)

WATER CONSUMPTION

3.1.Water Consumption

Buildings can be designed with appliances and fittings and management systems can be put in place to make the predicted water use of that building substantially lower than would otherwise be the case. Although the subsequent water consumption behaviour of the building’s users cannot be controlled the opportunities for using water much more sparingly are in place.

In residential buildings the following efficiency measures can be employed to reduce the building’s predicted water consumption

APPLIANCES / DETAILS
Spray Taps / Many taps can be retro-fitted with a spray head to reduce the flow of water. Account should be taken of who would be using the tap and for what purposes.
Flow
Regulation / Due to the water pressure being set by water companies,
regulation is generally more applicable than restriction. The maintenance of a standard flow rate can be achieved by in-pipe fittings, or outlet fittings, such as specially adapted shower heads.
Water-efficient Toilets / Toilets can account for 25% of water-use in a typical
household. Low-flush toilets and dual-flush toilets are inexpensive ways to rein in the amount of water used. Low-flush toilets simply use less water in the cistern, whereas dual-flush toilets can vary the flush depending on the amount of waste.
Urinals / Depending on the potential usage of urinals, systems to restrict flushing, or even remove flushing, can be employed.
Showers / Generally, showers use less water than baths, however this is mainly due to personal preference when washing. Power showers are actually more likely to waste water than a bath. Fitting a flow-regulation device to the shower head can maintain both the comfort and water-saving aspects of usage.
Washing Appliances / Although not strictly a construction issue, many new homes are fitted with washing machines and dishwashers, the use of energy efficient appliances (usually A or B rated) can help to cut water usage.
Meters / Water meters do not specifically save water themselves but can cut consumption. By linking water habits to a charging structure, it is likely that householders and businesses alike will take steps to ensure that less water is wasted.

Devices and Appliances to Save Water (Source: Maidstone Borough Council Sustainable Construction SPD Part 1- Using Water July 2006)

Code Credits

There are mandatory requirements for decreasing levels of predicted water consumption at different levels of the Code and there are a maximum of 5 potential credits in Wat 1.

Water consumption (litres/person/day) / Credits / Mandatory Levels
≤ 120 / 1 / Levels 1 and 2
≤ 110 / 2
≤ 105 / 3 / Levels 3 and 4
≤ 90 / 4
≤ 80 / 5 / Levels 5 and 6

(From Wat 1 (Internal Potable water Use) CSH Technical Guide)

Credits are based on the predicted average household consumption calculated using the BRE Code Water Calculator and includes any reductions of mains supply due to rainwater harvesting and/or greywater recycling systems.

BREEAM Credits

BREEAM credits for non-residential buildings are awarded in the following ways:

• based on the improvement over standard specification of water fittings, calculated using the BREEAM water calculator including the reduction of supply through rainwater or grey water systems.
• where evidence that a water meter with a pulsed output will be installed on the mains supply to each building.
• where evidence that a leak detection system is specified or installed.
• where proximity detection shut off is provided to water supply for all urinals and
• where evidence that there are established and operational maintenance procedures covering all sanitary fittings.
• where evidence water consumption is monitored and recorded at least once every quarter.
• Where evidence is provided to demonstrate the specification of systems that collect, store, and where necessary, treat rainwater or greywater for WC and urinal flushing purposes. (Some BREEAM assessments only, e.g. BREEAM Schools)

Model Essential Requirement 3.1

* At the time that planning permission is granted

Compliance Check

Residential:

Up to 2011: Level 3 certificates at both design and post construction phases

2012-2016: Code FSH Assessor’s reports at design stage and post construction stage stating at least 4 no. Wat 1 credits achieved.

From 2016: Level 6 Code FSH certificates at both design and post construction phases

Non-residential and Multi-residential:

Up to 2011: BREEAM Assessor’s reports at design stage and post construction stage stating at least 50% of BREEAM Water credits achieved.

2012-2016: BREEAM Assessor’s reports at design stage and post construction stage stating at least 60% of BREEAM Water credits achieved.

From 2016: BREEAM Assessor’s reports at design stage and post construction stage stating at least 70% of BREEAM Water credits achieved.

Planning Implications

More efficient appliances are unlikely to have any implications for the external visual appearance of buildings.

Further Guidance and References

ENVIRONMENT AGENCY, National Water Demand Management Centre, A Study of Domestic Greywater Recycling (2000)

ENVIRONMENT AGENCY: Assessing The Cost Of Compliance With The Code For Sustainable Homes WRc Ref: UC7231.

CIRIA, Buildings that Save Water (2001)

CIRIA. C522, Sustainable Urban Drainage Systems - design manual for England and Wales, (2000)

BRE, Water Conservation: a guide for installation and maintenance of low-flush WCs (1997) Available from CRC Tel: 020 7505 6622

BRE, Water Conservation: IP 2/00, Low Flow Showers and Flow Restrictors. (1997)

Available from CRC Tel: 020 7505 6622

DEFRA Water Supply (Water Fittings) Regulations, (1999)

RAINWATER HARVESTING & GREYWATER RECYCLING

3.2.Rainwater Harvesting and Greywater Recycling

Rainwater Recycling

Rainwater harvesting involves the channelling of water from one or more roofs via a filter into a storage tank placed in a convenient location. Table x displays the potential for water collection, depending on the size of roof used. Consequently, the installation of a single collection system is often more suited to a larger building; with smaller buildings benefiting from a linked, communal system, such as on a housing estate.

Rainwater harvesting potentially reduces the initial consumption of 150 litres/person/day to 80 l/p/d, although this will be dependent on rainfall and roof area. The potential rainwater yield is illustrated in the table below. The mean annual rainfall in South Hampshire is approximately 800mm

Table x

Roof Area (m2) / 50 / 75 / 100 / 125 / 150
Annual Rainwater Yield (litres) / 24000 / 36000 / 48000 / 60000 / 72000
Average Annual Consumption
(litres) / 55000

Rainwater Annual Yield (litres)( Source: The Environment Agency)

Water harvested from roofs has been shown to be suitable for use in toilets and washing machines. Additionally, it can be used for other non-potable purposes, such as general cleaning. A dual water supply ensures that when rainfall has been minimal, appliances such as washing machines (and any other use that relies principally on rainwater) can be switched to the mains supply.

The installation of a harvesting system is more cost-effective and less

energy-intensive if incorporated at the outset of construction.

The size of the storage tank is determined by considering the amount of water available for storage (a function of roof size and local average rainfall), and the amount of water likely to be used (a function of a building’s occupancy and function).

Where the installation of a rainwater system is unlikely (such as in an existing single dwelling), smaller measures can be taken usefully e.g. the use of garden water butts, which cost less and provide a quicker return on investment. All harvesting systems will require periodic maintenance to ensure their ongoing quality and effectiveness.

Commercial systems are usually larger, more sophisticated

versions of those used in the domestic situations.

Benefits

The main advantages to installing rainwater harvesting systems are:

• Up to 50% of main supply water can be substituted by stored rainwater thereby reducing overall water supply costs significantly;
• Dependence on the mains water supply is reduced and in remote areas rainwater harvesting can provide an off-site water supply;
• Used as part of a storm-water management scheme it reduces the amount of storm-water runoff and can control the flow-rate off site;
• The sustained water savings add value to the property as well as demonstrating commitment to conserving natural resources;
• Can dramatically reduce attenuation volumes for restricted run off situations.

Greywater Recycling

Greywater – the water that has already been used in hand basins, baths and showers – can be recycled to save up to 49 litres per person per day(l/p/day) representing on average 33% of household water use. After basic processing, the water can be reused around the home, including flushing toilets, watering the garden or general cleaning purposes i.e. windows, floors etc. The installation of a greywater recycling system is more cost-effective and less energy-intensive if incorporated at the outset of construction.

Source: Maidstone Borough Council Sustainable Construction SPD Part 1- Using Water July 2006

Case Studies

Underground storage tank

Code Credits

The Code for Sustainable Homes has no specific credits for reducing the consumption of potable water in the home by rainwater harvesting or greywater recycling but it will help to gain extra credits under Wat 1. The amount of rainwater or greywater that it is predicted can be collected and used per person is subtracted from the total potable water used per person to arrive at the final predicted potable water consumption per person in Wat 1.

Wat 2 encourages the recycling of rainwater/greywater for external use (for landscape/garden watering). See section 3.3 below.

BREEAM Credits

There are specific extra credits under some BREEAM assessments for greywater/rainwater recycling e.g. BREEAM School and BREEAM Courts (Wat 5). Other BREEAM assessments, e.g. BREEAM Office, do not have specific extra credits however all non-residential developments which reduce their total water consumption via rainwater harvesting will achieve more credits under the water consumption heading. (e.g. Wat 1 for BREEAM Office).

Model Essential Requirement 3.2

Compliance Check

Code FSH or BREEAM Assessor’s report to confirm the amount of predicted water consumption for each building or developmentwhich is reduced separately by rainwater harvesting and grey water recycling systems.

OR

(Where rainwater harvesting or grey water recycling systems absent) Receipt of a feasibility report clearly showing how either or both systems are not feasible in practical physical terms for any particular building or development.

Planning Implications

The visual impact would normally be minimal (ground level inspection covers) as the storage tanks are typically sited underground, or under the building’s roof. There may be implications for tree planting which would not be possible over or near to underground tanks.

Further Guidance and References

WATER REGULATIONS ADVISORY SCHEME. Information and Guidance Note 09-02-04. Reclaimed Water Systems. Information about Installing, Modifying or Maintaining Reclaimed Water Systems (1999)

ENVIRONMENT AGENCY, Conserving Water in Buildings 4: Rainwater re-use,

UK RAINWATER HARVESTING ASSOCIATION (UKRHA)

Figures for UK rainfall are available from the Met Office

CIRIA Rainwater and Greywater Use in Building, Best Practice Guidance (2001).

WRAS Reclaimed water systems – information about installing, modifying or maintaining reclaimed water systems”; 9-02-04, (1999)

BSI BS1710: Specification for identification of pipelines and services, (1984)

BSI BSEN12056-3:2000: Gravity drainage systems inside buildings. Roof drainage, layout and calculation, (2000).

Grey Water website:

Rainwater harvesting website:

EXTERNAL WATER CONSUMPTION

3.3.External Water Consumption

Approximately 13 % of domestic water consumption is via external taps mainly for watering the garden but also for cleaning cars and outside surfaces. Many non-residential buildings also use significant quantities of water for maintaining their landscaped areas.

Rainwater could be collected to reduce the amount of mains water used for these purposes as well as reducing the amount of water being discharged into drains and watercourses, and the risk of localised flooding and the overall water bills for householders and non-residential users.

The simplest and most cost effective system for rainwater collection is the water butt. This typically intercepts water from the rainwater down pipes. More complex central collection communal systems, (using the same principles as the water butt), are available for apartment blocks.

Collection of rainwater for use in the dwelling, e.g. for WC flushing, is covered in section 3.2 above. If a rainwater harvesting system is implemented for internal water use, external taps can also be supplied.

Source: combinedharvesters.co.uk

Code Credits

Wat 2 (External Potable Water Use) awards one credit for a correctly specified system to collect rainwater for a garden, patio or communal garden space. The size requirement for the potential maximum storage of collected rainwater varies according to the size of the dwelling and the type of garden space. Detailed specifications are provided for the rainwater collector to meet the Code’s requirements for this issue.

Pools hot tubs or other large water-using features which are fed by mains water, will automatically mean a score of zero for this issue. This rule applies whether it is an internal or external pool. Where pools are present, credits can only be awarded if the features use 100%

rainwater or 100% recycled water.

BREEAM Credits

There are no specific extra credits under BREEAM assessments for rainwater recycling to supply outside taps for non-residential buildings.

Model Essential Requirement 3.3

Compliance Check

Residential:

Code FSH Assessor’s reports at design stage and post construction stage stating that the Wat 2 credit has been achieved.

Non-residential and Multi-residential:

The developer to submit details of the amount of square metres of landscaped area (private and communal gardens) associated with the development or buildings as well the provided rainwater collection storage capacity.