Ecoisland Project, Isle of Wight

Project: Ecoisland Project, Isle of Wight

Summary Benefits

The reAqua system offers savings of £300-600 per year in a family home with a typical payback period of 3-5 years. In addition to the annual savings it qualifies for double code points under the Code for Sustainable Homes for its water and energy savings.

Product Overview

Waterevolution’s reAqua system unit is the ideal solution for securing CfSH code points AND reducing running costs for your buildings. The reAqua unit saves money by reducing water consumption. The reAqua+ unit saves money by reducing both water and energy consumption. Both units collect greywater from the bath or shower. The reAqua+ also transfers heat from the water back into the central heating system. The treated greywater is then fed to toilets for flushing.  The reAqua system reduces water consumption by up to 30% and can also save up to 50% of the energy used to heat bath and shower water.

Water savings

 

The reAqua+ is in use on the Isle of Wight as part of Ecoisland home trials.  The recycled use of greywater has completely eliminated the use of potable water for flushing toilets delivering a 30% saving on consumption in the household. This confirms industry-accepted figures for the percentage of water used to flush toilets in the home.

The Isle of Wight is supplied by Southern Water at 0.3214p per litre (a combined potable water and sewerage charge).  From the Ecoisland study the occupants have saved between 205 and 477 litres of water per person per week.  This gives an annual saving on water charges of between £34 and £79, per person or £136 - £316 for a family of 4.

Using the same principle for South West Water illustrates the alternative savings that would apply.  South West Water charge 0.527p per litre (pre April ’13).  A saving of 205-477 litres per person per week in this region would therefore save between £56 and £130 annually per person or £224 - £520 annually for a family of 4.

In the Thames Water region, with charges of 0.190p per litre per person, the reAqua+ would typically save between £20 and £47 per person per year or £80 – £188 for a family of 4.

Water charges are rising as of 1 April 2013 delivering greater savings through reAqua+ and cutting the payback period even further.

Annual water saving

Southern Water

South West Water

Thames Water

Per person @ 205 litres saving/wk

£ 34

£ 56

£ 20

Per person @ 477 litres saving/wk

£ 79

£ 130

£ 47

Family of 4

£ 136 - 316

£ 224 - 520

£ 80 - 188

Based on a typical fully-installed cost for the reAqua unit (water only) this water saving alone would deliver an average pay-back period of around 5 years reducing to 3 in the more expensive water region.

Energy savings

 

The reAqua+ unit is SAP Appendix Q eligible as a Greywater Heat-recovery (GWHR) device. It has been tested by BRE and will soon appear in the Appendix Q calculator.

Using European Standards EN13203 Tapping Cycles (simulations of domestic water & energy usage patterns) BRE has provided the following assessment of the reAqua+ performance in a home where electricity is used for water heating.

Annual energy saving

Family of 4

BRE, Tapping cycle 2*

£ 64

BRE, Tapping cycle 3**

£ 93

‘Real-world’ study

£ 145

*   2 showers of 53 litres per day at 36ᵒC
** 1 shower and 2 baths per day at 73 and 180 litres respectively at 30ᵒC

The ‘Real-world’ study is based on data taken from the Ecoisland homes where water/energy consumption is typically 1 shower per person per day and 4 flushes per person per day.

Based on the incremental cost of the reAqua+ unit over the reAqua (water-only) device, the energy saving potential equates to a similar average payback period of 5 years dropping to 3 based on the ‘Real-world’ data.

Code for Sustainable Homes

The reAqua system offers two sets of code points under the Code for Sustainable Homes as it provides both energy and water saving solutions for the home.

Wat 01 – Internal Water Use

  • Helps to gain Code3 or 4 level Water level of 105 litres per person per day:
    3 credits/4.5 points and a mandatory threshold
  • Or helps to gain maximum water reduction of 80 litres per person per day:
    5 credits/7.5 points and mandatory Code level 5 and 6 threshold

Ene 01 – Dwelling Emission rate – reAQUA+ reduces CO2 emissions by reducing water heating fuel used. NB:  actual credits gained depends on the individual SAP calculation and fuel type.

Not only does it deliver class-leading water savings of around 30% of consumption but it does so without the need for flow restriction and low-volume devices that can impact on lifestyle and comfort and may also cause maintenance problems when wastepipes fail to clear adequately under low-volume flow. The reAqua philosophy is reuse rather than rationing as a better route to water saving.

The reAqua system is ‘fit and forget’ requiring no action or control by the occupier. To meet the British Standard for greywater it requires an annual replenishment of the proprietary disinfectant contained within the unit. This top-up is programmed to coincide with the annual boiler maintenance call.