COMMERCIAL SHOWERHEAD METERING STUDY

April 5, 2011Regional Technical Forum

Presented by: Michael BakerSBW Consulting, Inc.

Study Objective

Statistically reliable estimates of electrical energy savings from the installation of low-flow showerheads on showers operated within commercial buildings.

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Possible Market Segments

Hospitality (Guest rooms). Health (Assisted Living and various types

and nursing and convalescent care). Businesses that provide shower facilities

for employees. Dormitories Recreational (community centers,

swimming pools, health clubs)

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Measure Specification

Propose to use Sunbeam unit

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Showerhead Model Flow Rate Approximate Retail Pricing

Sunbeam Rotating 1.5 gpm at 60psi $10/unit

Niagara Sava 1.5 gpm at 60 psi $10/unit

Bricor SuperMax 1.25 gpm at 50 psi $80/unit

Results from Cascade Water Alliance Pilot

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Shower room total measured for public pool and community center

Research Plan

Random sample of King County commercial parcels (Tax Assessor database)

Telephone interview Are there showers in the building that get regular

use? Fuel used for water heating? (supplemented by

SBW direct install database) Random selection of showers in regular use

with electric water heat, by market segment

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Sample Size

Based on variance observed in metering of single family shower use

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Number of Market Segments

Sample Size by Confidence Level / Relative error

90/10 90/15 80/15 80/20

1 179 88 56 32

2 358 177 111 64

3 537 265 167 96

4 716 353 223 128

5 894 441 278 161

Measurement Procedure

Three visits to each site for engineering data First visit

Select random shower head One-time flow measurements Install TOU flow meter

Second visit Download and check pre data Install new low flow showerhead

Third visit Download and check post data Restore old head if requested

Satisfaction survey

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Metering Design

Time of use flow metering for individual shower heads

Allows comparison of pre and post shower duration

Clark Solutions Model CLXC-150-H-S, dry type, single-jet totalizing water meter.  Provides a digital output signal for every gallon of water used. Onset model U9-001 event logger records the date and time each gallon of water used . 

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Savings Analysis

Identify separate shower events in time-series Compute number of shower events in pre and

post and average gallons per event Estimate total events per year using full

record adjusted to reflect information about the daily,

weekly and seasonal operating schedule obtained from facility staff

Estimate mixed water temperature

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More Savings Analysis

For pre and post conditions: Annual energy use (kWh/year/head) = Annual Mixed water use(gal/year) * [Mixed Water temperature (°F) – Cold Water temperature (°F)] * Density (8.33 lb./gal) * Specific Heat (1 Btu/lb. °F) ÷ Domestic hot water efficiency ÷ 3413 Btu/kWh.

Savings is the difference between annual pre and annual post

Compute market segment average savings

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