commercial showerhead metering study
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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.
24/5/2011
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)
34/5/2011
Measure Specification
Propose to use Sunbeam unit
44/5/2011
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
54/5/2011
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
64/5/2011
Sample Size
Based on variance observed in metering of single family shower use
74/5/2011
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
84/5/2011
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 .
94/5/2011
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
104/5/2011
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
114/5/2011
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