HomeMy WebLinkAboutPOWERHOUSE 2 - FDP220015 - SUBMITTAL DOCUMENTS - ROUND 3 - ALTERNATIVE COMPLIANCE REQUESTDear Rick Surbrugg,
(PEC Responses and edits in Red in body of letter so letter can be responded to point by point)
This letter is to following up with Neenan Archistruction regarding Neenan’s application for alternative compliance for the required Water Supply Requirement (WSR) for CSU Powerhouse
2. In a letter dated December 6, 2022, Professional Engineering Consultants (PEC) provided a justification for the estimated annual water consumption at Powerhouse 2 of 579,500 gallons
or 3.021 gallons per square foot per year. PEC’s methods for determining theWSR of Powerhouse 2 can be summarized as follows:
Powerhouse 2 will have similar occupancy types as Powerhouse 1 including office spaces, conference rooms, assembly rooms, and lab/research space.
Because Powerhouse 1 and 2 have similar occupancy types, PEC has assumed that the WSR per square foot of indoor building space will be similar and Powerhouse 1 can be used as a comparable
for Powerhouse 2.
Powerhouse 1 is approximately 77,000 square feet and Powerhouse 2 is approximately 167,530square feet.
Powerhouse 1 has a single water tap that serves all typical indoor water use as well as irrigation and evaporative cooling.
Powerhouse 2 will have a separate irrigation tap and will not utilize water for evaporative cooling.
Because water use for irrigation and evaporative cooling only occurs in summer months (May through October), PEC only used water use data from November2016 through March 2023 to not
include months with irrigation and evaporative cooling.
During this time period water consumption ranged from 8,400 to 87,100gallons per month and averaged 1,080 Gallons per day.
PEC divided the average gallons per day by the total area of powerhouse 1 (PH1) to give a approximate daily usage of 0.0141 gallons/day/sqft. Powerhouse 2 (PH2) is anticipated to have
a 365 days per year occupancy. Daily occupancy is multiplied by 365 days to calculate annual usage.
Using this same WSR of 0.0141 gal/sqft/day, the 167,530 square foot Powerhouse 2 is estimated to have an annual WSR of 859,255 gallons.
The Water Resources Division of City of Fort Collins Utilities has reviewed this WSR justification and finds it to be inadequate. Each paragraph below points out a particular inadequacy
and a request for additional information.
Period of Record
PEC looked at a single year of water use data from the fall of 2020 to the spring of 2021. Water use data from Powerhouse 1 is available from 2016 through present. While PEC’s decision
to exclude summer months seems like a valid way to exclude water use for irrigation and evaporative cooling, there does not appear to be a good reason to not include other years of water
use at Powerhouse 1. It is possible that the 2020/2021 years were abnormal years of water use due to factors such as people working from home due to Covid restrictions. Please utilize
the entire available water use dataset from Powerhouse 1 in the analysis.
To give a more accurate representation of water usage for powerhouse, water usage from 2016 to 2023 has been used to calculate the updated estimated usage for powerhouse 2. The same
methodology that was previously used has been expanded on, utilizing winter water usage data from powerhouse 1 from 2016 to 2013.
Peak Annual Water Use
The methods used by PEC are an estimate of the average annual water use based on the 2020/2021 non-summer season. According to Section 26-149 of Fort Collins Municipal Code, “the applicant
shall provide the Utilities Executive Director with its estimated peak annual water use and any supportive information.” The WSR should be estimated as the peak annual water use.
Monthly water usage data excel file has been attached for reference. This file contains the full data set that was used from powerhouse 1 to estimate water usage for powerhouse 2. “Powerhouse
1 water Oct through May 2017 to 2023” gives the total monthly usage for powerhouse 1 for the years noted. As previously stated months may through October have been excluded due to the
increased water usage from irrigation and cooling. The “2023-04-17 PH2 Anual Water Usage Estimate” is the excel document used to calculate estimated water usage created and edited by
PEC.
Similar Floorplans
PEC states Powerhouse 1 and Powerhouse 2 have similar occupancy types and list office space, conference rooms, assembly spaces, and lab/research spaces. Please provide information to
support this statement including the square footage of each occupancy type fromthe as-built floor plans for Powerhouse 1 and the designed floor plans for Powerhouse 2.
The floor plan comparisons are as follows:
The above snips show the area and space type percentage for both powerhouse 1 and powerhouse 2.
The percentage of space in each building that is associated with “building core & circulation” & restroom spaces is similar between both buildings. With PH1 at 18.2% and PH2 at 18.8%.
The percentage of space in each building that is associated with “conference rooms” space is similar between both buildings. With PH1 at 5.4% and PH2 at 6.2%.
The amount of large occupancy spaces within each building is similar with PH1 being 2.5% classroom space and PH2 having 3.6% assembly spaces.
The two areas that differ slightly between powerhouse 1 and 2 are the lab and office areas. Powerhouse 2 will have approximately 10% more office space that powerhouse 1 did. Office spaces
include “research offices” and “student researchoffices”. All these spaces are anticipated to be similar occupancies since students will be using these spaces as strictly office spaces.
With 41.3% office space in PH1 and 51.7% in PH2.
The amount of lab spaces in PH1 does exceed that of PH2 by almost double. However due to the increased water consumption associated with lab spaces, using the PH1 water usage for estimates
of water consumption will give a more conservative estimate in case additional spaces in PH2 are converted to labs in the future as was previously discussed by ownership team.
Cooling Water Requirements
PEC states Powerhouse 2 will not utilize cooling methods that do not continuously consume water to produce cooling. Please provide information about the planned cooling system for the
Powerhouse 2 and any water requirements.
The proposed cooling system will be a full geothermal system with water-to-water heat pumps at individual zones within the building and outdoor/ventilation air being handled by RTU's/DOAS
units with internal heat pumps tied to the geothermal loops. Neither of these systems will utilize domestic water for cooling beyond the initial system filling and a small amount of
makeup water if geothermal system requires maintenance or a leak occurs in the system.
Calculation of Annual Volume Requirement
PEC estimated an annual water requirement for Powerhouse 2 of 579,500 gallons. This appears to be a miscalculation as it is not the product of 3.021 gal/sqft/yr and 165,000 sqft. Please
clarify the inputs or correct this calculation.
Updated calculations have been stated in the notes above, yielding an estimated peak water usage for the new building of 0.0141 gal/sqft/day (5.1465 gal/sqft/day). For the 167,530 square
foot Powerhouse 2 is estimated to have an annual WSR of 859,255 gallons.
Updated calculations and explanations performed by:
Chad Schilt
Professional Engineering Consultants
Chad.schilt@pec1.com
We look forward to working with you to come to a conclusion on what the WSR should be.
Sincerely,
Jen Dial, Water Resources Manager
Cc: Miles Daly, Water Resources Engineer