The water-smart home

Element - - Home - By Jo­hann Bern­hardt

De­mand man­age­ment

The best bang for your buck is to save water by installing water sav­ing de­vices and by keep­ing an eye on our habits. • In­ex­pen­sive, low-flow shower heads can be in­stalled in the shower to re­duce flow rates from over 10 litres per minute to be­tween 7.5 and 9 litres. • The same can be done with kitchen, laun­dry and bathroom taps (for pur­chases of such de­vices check ecomat­ or safe­wa­ter. • When buy­ing new ap­pli­ances like wash­ing ma­chines and dishwashers it pays to check the star rat­ing of the Water Ef­fi­ciency La­belling Scheme (WELS) the more blue stars on the la­bel, the lower the water con­sump­tion. • Whether in a new house de­sign or the ren­o­va­tion of an ex­ist­ing house, one of the most ben­e­fi­cial steps to take is to lo­cate kitchen, laun­dry and bath­rooms as closely to­gether as pos­si­ble and to place the hot water cylin­der in their vicin­ity. If toi­let cis­terns are to be re­placed as part of a ren­o­va­tion, it pays to in­stall a dual flush sys­tem that uses only three litres per flush (as op­posed to the 15 litres that older cis­terns might use). If retaining an ex­ist­ing cis­tern, sav­ings can be made by installing a ‘Gizmo’ cis­tern flush lim­iter. The cost of a Gizmo is min­i­mal, you can fit it your­self and the gains can be con­sid­er­able. • Fix leak­ing taps and pipes. • Com­mon sense can save water: turn off the tap while brush­ing your

teeth and fill the ket­tle with only the amount of water you need. We can harvest rain­wa­ter by installing a tank that fills from the roof gut­ters. When de­sign­ing a new house, it is a no-brainer to in­stall a tank, prefer­ably over 10000l, but a 4500l tank (1000 gal­lons) is a good start. Con­nect this to as many down­pipes around the house as pos­si­ble and use the water in the gar­den and in the house for toi­let flush­ing or clothes wash­ing. In this case, dual plumb­ing will have to be in­stalled in the house which is not dif­fi­cult to do at the con­struc­tion stage. It is more dif­fi­cult and costly, how­ever, when retrofitting a tank to an ex­ist­ing house. It also re­quires build­ing con­sent. If that cost is pro­hib­i­tive, a more eco­nom­i­cal op­tion is to use a smaller, slim-line rain­wa­ter tank which fits un­der the eaves, and to use the water only for wa­ter­ing the gar­den (no con­sent re­quired).

Up­grad­ing rain­wa­ter to be used for drink­ing pur­poses makes sense mainly in ar­eas where there is no retic­u­lated water sup­ply as the re­quired treat­ment is not only ex­pen­sive to in­stall but also to run. Build­ing con­sent is also re­quired for this.

Water heat­ing

The water we use in our homes is now me­tered and charged for across Auck­land and in other cities. With the av­er­age house­hold in Auck­land spend­ing $750 a year for their water/wastew­a­ter bill, we have a per­fect rea­son to con­sider op­por­tu­ni­ties to save water and dol­lars at the same time.

Water, along with food, sun­light and air, is vi­tal for our sur­vival. Most parts of this ‘land of the long white cloud’ are blessed with co­pi­ous amounts of rain­wa­ter. Yet water short­ages oc­cur and oc­ca­sions where de­mand for potable water out­strips sup­ply are in­creas­ing. How can that be?

For a long time we have treated water as a free and abun­dant com­mod­ity and haven’t re­ally looked af­ter it the way it de­serves. In ad­di­tion, in­creas­ing water needs for en­ergy gen­er­a­tion, farm­ing and do­mes­tic sup­ply all have af­fected the qual­ity and avail­abil­ity of water. Our cities are cov­ered with im­per­me­able sur­faces send­ing pre­cious rain­wa­ter straight into streams and har­bours in­stead of al­low­ing it to per­co­late through the soil, re­plen­ish­ing aquifers in the process.

Here’s where we can help: there are two main ways to re­duce our de­pen­dence on town sup­ply – de­mand man­age­ment (use water wisely) and rain­wa­ter har­vest­ing and re­use.

Rain­wa­ter har­vest­ing

The po­si­tion­ing of the hot water cylin­der close to wet ar­eas like the kitchen, laun­dry and bath­rooms can not only lower water con­sump­tion but also re­duce the en­ergy needed to heat the water. If you want to lower the on go­ing en­ergy costs for water heat­ing, here are three good op­tions: • So­lar hot water pan­els gen­er­ate more hot water than we need in sum­mer, but not enough in win­ter, when the hot water has to be topped up reg­u­larly by electricity, wood (see be­low) or gas. • Water-heat­ing heat pumps work all year round and don’t need sun­shine in win­ter to gen­er­ate hot water. This makes them more eco­nom­i­cal in win­ter but not as pro­duc­tive as so­lar hot water pan­els in sum­mer. • A third water heat­ing sys­tem is the good old wet­back. The water cylin­der is con­nected di­rectly to a free-stand­ing fire­place and the water is cir­cu­lated through the sys­tem. The wood­burner needs to have a 65 per cent en­ergy ef­fi­ciency rate and the cylin­der needs to be el­e­vated to the fire­place to al­low the hot water to rise into the cylin­der.

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