Presentation at the 2011 USGBC Illinois Chapter Credential Maintenance Day by Rob Young and Scott Bowman. Using the LEED Platinum Wellmark BCBS Headquarters in Des Moines, Iowa as a case study, the presenters provide factors related to rainwater capture systems, how LEED credits relate, demonstrate the system from design through start-up, and discusses pros and cons of rainwater capture and flushing systems.
1. USGBC Illinois Chapter
November 1, 2011
Taking Water Efficiency
to the Limit
Presented by:
Scott Bowman, P.E., LEED AP BD+C
Rob Young. P.E.
Slow the Flow
2. Learning Objectives1
• Feasibility factors of a rainwater capture
system
• Evaluate LEED guidelines
• Comprehend system design through
implementation
• Weigh pros and cons of rainwater capture
6. Why should we care?
• Water is a undervalued resource, at least
in the Midwest
• Potable water use is increasing at 2x the
rate of world population growth
• 100 years ago, we used 10 gallons of
water a day1today we use 100!
• Americans spend $523 on water per year,
and $707 on soda!
7. Why should we care?
• Save some money
• Reduce pollution
• Reduce reliance on aging infrastructure
• Conserve energy
13. Why do we care?
• Energy is used to deliver water
– Pump from source
– Treat to potable standards
– Distribute to use
– Desalination
– Waste water treatment
14. Why do we care?
• Water is linked directly to energy
– Cooling towers of power plants
– Direct cooling of power plants
– Scrubbing of plant discharge
– Oil recovery
– Bio>fuel production
• 8% of freshwater withdraw around the
world is for power plants!
15. Why do we care?
• LEED is often invisible
• Energy efficiency is tough to visualize
• Water use is a common language
• Rainwater capture is a tangible
benefit1you can see it!
• Every project needs a story1
17. LEED and Water Efficiency
• Some changes in v2009
• Not a major change in the way credits are
calculated
• New prerequisite
• Baseline has been clarified, making credits
more difficult to achieve
• Values changed, impact similar
20. WEp1 Reduce by 20%
• First credit of v2.2 is now prerequisite
• This savings was so easy, it is now
mandatory
• Baseline fixtures now defined by table in
the standard
• Baseline lavatories are clearly now 0.5
gpm (rather than 2.5 gpm)
Water Use Reduction
21. WEc2 Innovative
Wastewater Technologies
• Increased to 2 points
• Reduce generation of wastewater
• Reduce potable water use for sewage
conveyance by 50%, or1
• Treat 50% of wastewater on site to tertiary
standards
• Waterless urinals or composting toilets
22. WEc3 30>40% Reduction
• Now three levels up to 40%, first step
gains 2 points, 4 total possible
• Maximize water efficiency in buildings
• May be difficult to reach higher levels with
only fixture selection
• Higher levels will require rainwater capture
Water Use Reduction
23. IDc1 45% Reduction
• Exemplary Performance ID credit
• Adds one more point
• Requires 45% reduction from baseline
• Waterless or ultra low urinals required
• Rainwater or Gray Water
Water Use Reduction
24. Pilot Credits
• PC10 – Sustainable Wastewater
Management
– Focus on innovative systems
– Recovery and treatment
– Reduces Threshold to 25%
• PC17 – Cooling Tower Makeup
– Modification of EBOM credit
– Controlled blowdown and filtration
• PC18 – Appliance and Process Water Use
Reduction
– Modification of LEED for Schools credit
– Minimum performance for different equipment
25. LEED Healthcare
• WEc2 – Measurement and Verification
• WEc4.2 – Cooling Tower Makeup Water
• WEc4.3 – Food Waste Systems
• ID credits can be from different product)
26. LEED 2012?
• WEp1 – Landscape Water Use Reduction
• WEp2 – Minimum Fixture and Fitting
Water Use Reduction
• WEp3 – Appliance and Process Water
Use Reduction [PC18]
• WEc1 – Additional Landscape Water Use
Reduction
27. LEED 2012?
• WEc2 – Additional Fixture and Fitting
Water Use Reduction
• WEc3 – Sustainable Wastewater Systems
[PC10]
• WEc4 – Cooling Tower Makeup Water
[PC17]
• WEc5 – Additional Appliance and Process
Water Reduction
29. Water Efficient Design
• Thought process for reducing
water usage.
1) Baseline
(Demographics / Usage)
2) Conserve (Fixture Selection)
3) Generate (Reclaim, store, treat,
and distribute Rainwater,
Graywater, Condensate,
Subsoil Drainage)
FTE’s
Demographics
Usage
Fixture
Types
Human
Waste
Rainwater
Capture
Total
Water
Rainwater
Capture
31. Water Efficient Design
• Once it has been determined
that rainwater capture is
necessary:
– Refine goals.
– Define cistern size.
– Iterate with goals to determine
proper size and type.
– Determine diagrammatical layout,
equipment, and treatment.
Rainwater
Capture
Goals > %
Cistern
Size/Type
Pumps /
Piping
Treatment
37. LEED NC v2.2
WEc2 / WEc3 Calculations
Note that this drops to 43.2%
under LEED v2009!
38. Fixture Selection
• Which fixtures contribute the most?
– Based on WEc3 – total water usage
– Assumes 50/50 gender distribution
Baseline Water
Usage
Percentage
of Total Use
Lowest Possible
Water Usage
Potential for
Savings
Urinals 1.0 22% 0 21.6%
Men's Water Closets 1.6 17% 1.28 3.5%
Women's Water Closets 1.6 52% 1.1/1.6 10.8%
Lavatories 0.5 6% 0.5 0.0%
Sinks 2.5 1% 2.2 0.2%
Mop Basins 2.5 1% 2.5 0.0%
Total 36.1%
39. Fixture Selection
• Lavatories: 0.5 gpm base, 15 second use
– Sensor faucets save additional 20% (12
second use rather than 15 second)
• Sinks: 2.5 gpm base
– Standard 2.2 gpm faucets save 12%.
• Showers: 2.5 gpm base
– Many options available. Beware of
performance!
40. Fixture Selection
• Urinals – 1.0 gpf base
– Waterless Urinals
• Save 100%
– 1/8 gpf urinals
• Save 87.5%
• Sensor only
– 1/2 gpf urinals
• Save 50%
• Manual / Sensor
41. Fixture Selection
• Water Closets – 1.6 gpf base
– Dual Flush
• 1.1 / 1.6 gpf
• Save 21%
• Manual / Sensor
– Low Flow
• 1.28 gpf
• Save 20%
• Manual / Sensor
• Requires special bowl
46. Rainwater Capture Design
• Cistern sizing – what’s the big deal?
– Inputs
• Monthly Rainfall – how many events per month?
• Other inputs (subsoil, condensate, site, etc)
• How much water can be captured?
– Roof capture coefficients
– Filter efficiencies
– Outputs
• Daily usage
• Overflow
47. Rainwater Capture Design
• Cistern sizing – what’s the big deal?
– Other uses
• Irrigation (Landscape Architect)
• Stormwater Detention (Civil Engineer)
– The mechanical engineer cannot size cisterns
for these types of systems.
• Conclusion – not just a tank in the ground!
49. Rainwater Capture Design
Material List
• Roof Drains
• Pre>Filters
• Cisterns
• Intake Filters
• Pumps
• Final Filters
• Final Treatment
• Day Tank
• Makeup Water
• Level Sensors
• Booster Pumps
• Meters
)following a drop of water
60. Rainwater Capture Design
• Hydraulic implications
– Adding two sets of pumps
• Reclaim Pumps (cisterns treatment day tank)
• Booster Pumps (to distribute to flush valves)
61. Rainwater Capture Design
• Multiple Levels of Metering
– Main Meter
– Sanitary Add
• Flushing Reclaim
– Sanitary Deduct
• Irrigation Makeup
62. Rainwater Capture Design
• Other types of water to consider for re>use
– Subsoil drainage
– Cooling coil condensate
– Gray water (possibilities exist for 5>25%
savings depending on lavatory and shower
selections)
63. Rainwater Capture Design
• Code implications
– Get the code officials involved early – this is new to
most of them.
• Uniform Plumbing Code – Chapter 16
– No direct connection to any potable water system
– Building and equipment room signage
– Pipe and equipment labeling
– Tank>type water closets
64. Rainwater Capture Practice
• Keeping the Cisterns Clean
– Pre>Filters
– Aeration
– Chlorination
– Natural (Biofilm)
68. Wellmark BCBS
• HOK
• RDG Planning & Design
• Snyder Associates
• KJWW Engineering
• The Weitz Company
• Baker Group
• Baker Electric
• The Weidt Group
77. Wellmark BCBS
• 2,330 full time equivalents
– Established for LEED and Design purposes
• 70/30 split women to men
• Current Water Modeling:
– 55.8% reduction in human water flushing
– 57.9% reduction in total water use
• 8,000 gallons per day required for flushing
Note that all values related to this project are for design purposes
based on averaged historical data. Actual performance cannot
be confirmed until after final construction and commissioning.
80. Wellmark BCBS
• Achieved 7 LEED points related to Water
– SSc6.1 – 1 point
• Stormwater Detention (integrated into system)
– WEc1 – 2 points
• No water use for irrigation
– WEc2 – 1 point
• Greater than 50% reduction in wastewater flushing
– WEc3 – 2 points
• Greater than 30% reduction in water use
– IDc1 – 1 point
• Exemplary performance, Greater than 40% reduction in
water use
89. Wellmark BCBS
• Mechanical Site Work
• Piping cost would normally be
in site budget
Material Labor Total
1.07% 0.25% 1.31%
Material Labor Total
0.75% 0.16% 0.91%
2.23%Total cost for site and cistern piping and pre-filters
Mechanical Site Work as Percent of Site
Underground site piping
Vault pre-filters and piping
90. Wellmark BCBS
• Reclaimed Water System Costs
Less than 0.8% Mechanical Budget
Material Labor Total
Reclaim water pumps 0.14% 0.08% 0.22%
Reclaim tank 0.41% 0.07% 0.48%
Pressure booster pump 1.33% 0.06% 1.39%
Meters/solenoid valves 0.06% 0.02% 0.08%
Total 2.17%
Irrigation System Costs as Percent of Plumbing
Material Labor Total
Reclaim water pumps 0.14% 0.08% 0.22%
Final filters 0.11% 0.07% 0.18%
Ozone generator 0.68% 0.06% 0.74%
Reclaim tank 0.41% 0.07% 0.48%
Pressure booster pump 0.51% 0.06% 0.57%
Meters/solenoid valves 0.09% 0.02% 0.11%
Total 2.31%
Flushing System Costs as Percent of Plumbing
91. Wellmark BCBS
• And the grand total is1
Less than 0.5% of Total Construction!
1.90%
0.91%
Flushing system costs 0.41%
Irrigation system costs 0.38%
Plumbing fixture premium 0.01%
Misc piping/labels/valves 0.19%
3.81%
Perecent of Mechanical for Reclaim Water System
Total
Cistern piping/pre-filter cost
Flushing Cistern
94. Wellmark BCBS
• Wellmark will1
– Save 7,200 gallons of water a day
– Will not discharge 1,550,000 gallons of
sewage
– Save 2,600,000 gallons of water a year
• Enough to fill four Olympic sized pools
each year
95. Wellmark BCBS
• Or thinking of a standard water cooler1
• 1435 Water Cooler Bottles a Day
• 520,000 Bottles a year!