Roof Rainwater Harvesting: Questions Answered

Published on December 2021 | Categories: Documents | Downloads: 11 | Comments: 0 | Views: 43
of 2
Download PDF   Embed   Report

Comments

Content

 

I TI

  Roof Rainwater Harvesting

Questions

nswered

  y Anne K Goedken

Previous generations collected water in bar rels and used the contents for watering gar

ing a project

dens and plants. Today, water is being har vested and reused on a much larger scale to save money, earn LEED points, and tell a

th thee safe safest st wat ater er poss possib ible le..

stor story y abou aboutt sust sustai ain n abil abilit ity y in acti action on..

best suited for new construction.

ultraviolet treatment

ing, but according

Just as it does in any building, the roof serves as the collec

and

What is it used for? The primary application

How do does es it work? rk?

Filtering

of the rainwater are also needed to produce

for rainwater

is usually toilet flush

to Yudelson, it varies depending

on the loca

tion and type of building. Because of the ratio of roof area to restrooms, low- to mid-rise commercial buildings are the best

tion point for rainwater. A roof washer is installed to remove dirt, rt, lea eave vess, and debris ris from rom the the roof perio eriod dica callly ly,, ensurin ring clean lean

candidates

water. Gutters or downspouts still carry the water away, but instead of depositing water to the ground, the gutters carry the rainwater to a storage tank. All we re really doing is taking

building, which would have a large surface area and few toilets to flush. In high-rise buildings, rainwater can also be used for

[the roofl system

(which is in place and designed

into every

building), intercepting the run-off, and diverting it to a storage tan ank k, explain lainss Jer errry Yudel elsson, sustain ainab abiility ity direct recto or at Inter ter face Engineering Inc. in Portland, OR. Yudelson is the author of Dev Develop elopin ing g Gr Gree een: n: Stra Strate tegi giees for for Suc Success cess

a primer on green

mark market etin ing g fo forr de deve velo lope pers rs.. The storage tanks are typically located underground ing garages or basements precast

concrete,

in park

and made of epoxy steel, fiber glass,

polyethylene,

or poured-in-place

concrete.

for a roof rainwater

system.

rai rainwater ater,, up to 80 perc rceent of rai ain nfa falll can be collected and used in a build ing. You re just not going to get it all, all, Y Yud udel elso son n emph emphas asiz izes es.. Tota Totall co col l lection

is impossible

due to negli

to collect 600 gallons of water per 1,000 square feet of roof area. The delivery and treatment system requires installation of a

Where does it work?  Th  The very first thing you try to do as you integrate a building design is [ask], What s nature me for for fre free?  The Northwest

........... .......... RAIN

..........

of

Although it s difficult to say how much water can be saved by reusing

Tank size is based on a mathematical equation, keeping this guideline in mind: For every inch of annual rainfall, it s possible

system em,, typi ypically ally mak akiing roo roof rain rainw water harv rves estt-

would be a

required fire-suppression storage by simply up s iizzing the tank, in incu curr rrin ing g mini minima mall extr extraa cost costs. s.

gible rainfall when the water pools and evaporates on the roof or when ov over erfl flow ow occu occurs rs duri during ng heav heavy y rain rain..

dual al-p -pllumbing ing

Irrigation

more suitable use for rainwater collected on a warehouse-type

for rainwater

going to give

Yudel elsson ex exp plai ain ns. is an ideal climate collection

because

Some mun Some munici icipal paliti ities es require buildings to label any source of ra rain inwa wate terr .

it

comes in fairly regularly and fairly gently. H Ho owever, many other areas of the country also receive enough rainwater to make harvesting it an option. According to (www.weather.com). Orlando, FL, receives an average of 48 inches of rain per year; 37 inches of precipitation falls yearly in

COOLING



BLACKWATER

PRODUCED



POTABLE



NO N P PO OTABLE



R AI NW AT ER

WATER

SUPPLY

WATER SUPPL Y

Dallas. Northerly cities like Chicago (38 inches per year) and New York City (46 inches per year) receive enough rainfall to make a harvesting system possible, but frozen precipitation needs to be taken into account. In extremely dry climates, such as Phoenix, where rainfall is less than 10 inches per year, rain

TOWER

water harves rvestting

CU.P.

is not as pra ract ctic ical al..

How much does it cost? One dollar per gallon of the tank s storage capacity is a simple cost cost esti estima mate te for for inco incorp rpor orat atin ing g a roof roof ra rain inw wat ater er-h -har arve vest stin ing g syst system em into a new-construction project. The bulk of the expense comes from the storage tank and the dual-plumbing ha hand ndle le th thee wate water. r.

system needed to co conti ntinu nued ed pa page ge

24

BUILD ILD IIN NGS

Augu sstt 2006

www. bu build ild in ings. co com

6

 

.••• .••• 11 ::11 11

Although rainwater systems are considered more of a LEED  po poin intt-ge gett tter er th than an an econo economi micc building measure at this point, there are some cases when they make financial sense. Yudelson

RAINWATER

0.5

G ROU NDWA TER

AS NEEDED

SUMMER

~

WATER

FROM

J

CITY

•••

points to Portland as an exam ple of one city whe herre stormwater hook-up fees are climbing dra matically. If you can avoid the hook-up fee, that can often pay for for the the en enti tire re syst system em,, he st stat ates es.. When looking at sustainable meas measur ures es,, Yu Yude dels lson on reco recomm mmen ends ds that building owners ask them selves, What s for free here that I can harvest, that s going to be there forever, and that I m not going to have to pay for over and overr agai ove again? n?

R EC lA IM ED

MGY

IRRIGATION

COOLING T OW OW E ER R

F IX IXTU R RE E

MA AK KE EU UP

US SE E

 P A R RK K BL LO OC CK KS 1. 2 MGY

1. 7 MGY

1. 5 MGY

FUTURE

BIO-REACTO BIO-RE ACTOR R

SEWAGE SEWAGE

TREATMEN TREATMENT T

5 MGY

MGY

=

MIL MIL LIO LION N

GA GAL L LON LONS S //Y YE EAR AR

SA AN N IT IT AR AR Y

What are the benefits? Wha The most obvious benefit of a rainwater system is LEED certification; up to 7 points can be garnered by installing a system in a new building. The process itself is inherently green - reusing rainwater reduces the stress on groundwater supp supplly an and d help helpss cu curb rb run un--off off and and er eros osio ion. n. Yudel udelso son n says says that that one of the most important benefits is using the process as a

a

SE EW WE ER R

MGY

B IO IO- S SW W Al Al E E..

W ET ET llA AN DS DS

TREATMENT

  DISPOSAL

te teac achi hing ng op oppo port rtun uniity for bu buiildin lding g occu occupa pant ntss an and d st stak akeh ehol old d ers. You can talk about a rainwater system, you can di diaagram it, [and] you can show it to people; you can even have cut outs where people see the rain. It s one of the [most] easily grasped sys ysttems that you can put in a buildi din ng [and have] the aver averag agee pers person on under underst stan and. d. .B.   nne

K

Goedken  [email protected]

pr prod oduc ucts ts ed edit itor or at Bu Buil ildi ding ngss maga magazi zine ne

is new

Sponsor Documents

Or use your account on DocShare.tips

Hide

Forgot your password?

Or register your new account on DocShare.tips

Hide

Lost your password? Please enter your email address. You will receive a link to create a new password.

Back to log-in

Close