20250801-AurariaMediumVoltageCapacity RPT.pdf

Auraria Campus Medium-Voltage

Capacity Study

Prepared By:

Prepared For:

AUGUST 1, 2025

Auraria Campus Medium-Voltage Capacity Study

RMH21454 Auraria Campus Medium-Voltage Capacity Study TOC i

TABLE OF CONTENTS

INTRODUCTION

CAMPUS DISTRIBUTION

EXISTING LOAD

NEW LOAD ADDED TO CAMPUS

NEW XCEL CALCULATED LOAD

NEW ARTS SWITCHGEAR CALCULATED LOAD

NEW HOLLY LOT SWITCHGEAR CALCULATED LOAD

RECOMMENDATIONS

RMH21454 Auraria Campus Medium-Voltage Capacity Study Page 1

Introduction

The purpose of this report is to determine the amount of spare capacity of the Auraria Campus medium-voltage electrical distribution system and forecast if the system has capacity for the future buildings currently in design. Over the next two years there are four new buildings being constructed on campus, as well as two buildings being moved off an Xcel Feeder and onto the campus distribution and one major renovation project. The campus is currently set up to be completely redundant from each building up to the Xcel substation. The redundancy is to remain on campus after the new loads are added.

RMH21454 Auraria Campus Medium-Voltage Capacity Study Page 2

CAMPUS DISTRIBUTION

The campus medium-voltage distribution system is a 13.2kV system owned and operated by Auraria

Campus facilities. Xcel Energy provides power to the campus with two redundant 16.92MW feeders

(#1308 and #2217) that feed a 1200A Automatic Throw-Over Switchgear (ATO) located in the Holly

Parking Lot. The ATO is fed from feeder #1308 on one side and #2217 on the other side, with an automatic throw-over switch-tie between the two buses. The configuration is commonly referred to as a

“Main-Tie-Main,” and is an important factor for reliability. Under normal operating conditions, the campus load is split roughly 50/50 between the two feeders, and if one feeder goes down, the ATO can operate and feed the whole campus from the feeder still in operation. This configuration can remain in use until the campus exceeds a load of 16.92MW, which is the capacity of the Xcel feeders. The ATO feeds two sets of switchgear, The Holly Lot gear and The Arts Building gear.

Figure 1 - Xcel ATO Switchgear

The Holly Lot gear consists of two Vista Switches located in the Holly parking lot. The two switches are “SWGR C” and

“SWGR D,” with “C” being fed from the 2217 side of the

ATO and “D” being fed from the 1308 side of the ATO.

There are three circuits coming out of each switchgear: 1C, 2C, 3C and 1D, 2D, 3D. The circuits are dual radial feeds

(1C/1D, 2C/2D, 3C/3D) and run through campus together so that each building connected to that circuit can be fed from either switchgear through pad-mounted switches or transfer switches within the transformers. Along with the dual feeds into the ATO this setup allows complete redundancy of the system in case an Xcel feeder, Vista

Switch, or Campus Circuit goes down all the buildings can remain online after switching is complete. Figure 2 - Holly Lot Switchgear

RMH21454 Auraria Campus Medium-Voltage Capacity Study Page 3

The Arts Building gear consists of two fused switchgear lineups located in the Arts Building. The two switchgear lineups are “SWGR A” and “SWGR B,” with “A” being fed from the 2217 side of the ATO and

“B” being fed from the 1308 side of the ATO. There are three circuits coming out of each switchgear: 1A, 2A, 3A and 1B, 2B, 3B. The circuits are dual radial feeds (1A/1B, 2A/2B, 3A/3B) and run through campus together so that each building connected to that circuit can be fed from either switchgear through pad-mounted switches or transfer switches within the transformers. Along with the dual feeds into the ATO, this setup allows complete redundancy of the system in case an Xcel feeder, fused switch, or campus circuit goes down all the buildings can remain online after switching is complete.

Figure 4 - Arts Building Switchgear

Figure 5 - Typical Transformer

Switching Configuration Figure 3 - Typical Pad-Mount Switching Configuration

RMH21454 Auraria Campus Medium-Voltage Capacity Study Page 4

EXISTING LOAD

The existing peak load at the Xcel ATO is 8.8MW when combining both Xcel feeders. This peak occurred in September of 2022. The peak over the last 3 years was 8.4MW in August of 2024. The current load profile on campus has peak load during the August and September timeframe when students are back in class and the weather is still hot. Over the winter months of November through March the peak load is lower at approximately 6MW.

The Owner provided the Engineer with building level metering data from October 2021 to May 2025. This data was compiled to determine the peak demand for each building, campus circuit, and campus switchgear.

The peak demand for the campus circuits and switchgear was determined by adding up the peak building loads for each month and determining the highest month. While this is not an exact peak demand load on each circuit or switchgear, it was the closest that could be accomplished since the only load data was monthly peak kW on each building. Since each building is likely not peaking at the same time or day, the actual load on the system is expected to be slightly lower than those shown below. For example, using this

Circuit

Existing Peak

Demand (kW)

Amps @

94% PF

1A/B 1259 58.7

2A/B 2975 138.6

3A/B 229 104.3

Arts Total 6365 296.5

1C/D 2597 121.0

2C/D 752 35.0

3C/D 867 40.4

Holly Total 4030 187.7 methodology the peak campus load is calculated at 10.4MW when the Xcel peak load metered at this time was 8.4MW. To get more accurate peak load information on the circuits and campus switchgear the engineer would need either 12 months of direct metering on the circuits/switchgear or 15-minute interval data for each building with matching timestamps. The campus has historically been at 94% Power Factor during peak load times so that is the Power Factor that is used in all our calculations.

kW

Date

Xcel ATO KW

RMH21454 Auraria Campus Medium-Voltage Capacity Study Page 5

NEW LOAD ADDED TO CAMPUS

Over the next 3 years, there are a number of buildings expected to be added to the campus grid. These buildings are a combination of remodels of existing buildings, existing buildings currently on Xcel services being moved over to the campus grid and new buildings to be built. Below is a list of new loads and the dates that are expected to be complete.

Building Timing Building Type Metered or NEC Calc

Load Added

(kW)

Boulder Creek 2025 Remodel NEC Calc 250

Admin/5th St Hub 2026 Existing Xcel Metered 807

Ballfield Ph 1 2027 New Build NEC Calc 6150

Health Institute 2027 New Build NEC Calc 1900

Ballfield Ph 2 2027 New Build NEC Calc 6150

Public Safety 2027 New Build NEC Calc 1360

NEW XCEL CALCULATED LOAD

Per the National Electrical Code (NEC), when adding load to existing equipment, metered load can be utilized but must be multiplied by 125% and added to the new NEC calculated load. The loads that are calculated below are based on NEC calculations. Based on these calculations, the campus would exceed the Xcel feeder size of 16.92MW sometime in 2027 (after the health institute was completed) and have a total load of 25.4MW after all buildings have been added.

However, Xcel Energy does not follow the NEC, they perform their own calculations based on energy model calcs and a multiplier based on their historical data. Because the feeders and ATO are owned and operated by Xcel Energy, it is their responsibility to do the final load calculations so the NEC calculations below are for reference only.

Building Timing

Metered or NEC

Calc

Load Added

(MW) Previous Total New Total

Historical Peak Current Metered 0 8.806 8.806

Boulder Creek 2025 NEC Calc 0.25 8.806 9.1

Admin/5th St Hub 2026 Metered 0.807 9.056 9.9

Ballfield Ph 1 2027 NEC Calc 6.15 9.863 16.0

Health Institute 2027 NEC Calc 1.9 16.013 17.9

Ballfield Ph 2 2027 NEC Calc 6.15 17.913 24.1

Public Safety 2027 NEC Calc 1.36 24.063 25.4

RMH21454 Auraria Campus Medium-Voltage Capacity Study Page 6

On July 14, 2025, Tanner Thompson at Xcel Energy sent Xcel load calculations to Auraria. These calculations are based on Energy Modeling data for Ballfields Phase 1 and 2. Based on their calculations the campus peak demand will be 16.82MW and below the capacity of their feeders.

Building Timing Metered or NEC

Calc

Load Added

(MW)

New Total

Demand

Historic Peak

Demand Current Metered - 8.806

Boulder Creek 2025 NEC Calc 0.25 9.056*

Admin/5th St Hub move to PG 2026 Metered 0.807 9.863

Ballfield Ph 1 2027 Energy Model .652 10.515

Health Institute 2027 NEC Calc 2.6 13.115*

Public Safety 2027 NEC Calc 1.36 14.475*

Ballfield Ph 2 2027 Energy Model 1.116 15.591

Tivoli move to PG 2027/2028 Metered 1.227 16.818

*Updates based on energy model and historical peak

8.81 8.81 9.06 9.86

16.01 17.91

24.06

0.00 0.25 0.81

6.15

1.90

6.15

1.36

Historical Peak Boulder Creek Admin/5th St Hub

Ballfield Ph 1 Health Institute Ballfield Ph 2 Public Safety

C am p u s D em an d

M W

Buildings Added to Campus

Auraria Campus Demand with Added Buildings

RMH21454 Auraria Campus Medium-Voltage Capacity Study Page 7

NEW ARTS SWITCHGEAR CALCULATED LOAD

The Arts Switchgear is currently slated to have two new loads added: Boulder Creek Remodel and the

New Health Institute Building. Both of these new loads will go on Circuit 1A/1B. Based on these calculations the circuits and switchgear have capacity for the added load. These load calculations do not include Ballfield Phase 2, as there is no additional capacity to add approximately 269A of additional load between the Arts Switchgear and Holly Lot Switchgear.

Circuit 1A/B Timing

Metered or NEC

Calc Load Added

(Amps @13.2kV)

Previous Total (Amps

@13.2kV)

New Total (Amps

@13.2kV)

Current Peak Load Current Metered 58.7 0.0 73.3

Boulder Creek 2025 NEC Calc 11 73.3 84.3

Health Institute 2027 NEC Calc 83.2 84.3 167.5

Circuit 1A/B NEC Calculated Load After Current Project Pipeline 167.5

Circuit 2A/B Timing

Metered or NEC

Calc Load Added

(Amps @13.2kV)

Previous Total (Amps

@13.2kV)

New Total (Amps

@13.2kV)

Current Peak Load Current Metered 138.6 0.0 173.2

Circuit 2A/B NEC Calculated After Current Project Pipeline 173.2

Circuit 3A/B Timing or NEC

Calc Load Added

(Amps @13.2kV)

Previous Total (Amps

@13.2kV)

New Total (Amps

@13.2kV)

Current Peak Load Current Metered 104.3 0.0 130.4

Circuit 3A/B NEC Calculated After Current Project Pipeline 130.4

Arts Switchgear Timing or NEC

Calc Load Added

(Amps @13.2kV)

Previous Total (Amps

@13.2kV)

New Total (Amps

@13.2kV)

Current Peak Load Current Metered 296.5 0.0 370.6

Boulder Creek 2025 NEC Calc 11 370.6 381.6

Health Institute 2027 NEC Calc 83.2 381.6 464.8

Arts Switchgear NEC Calculated After Current Project Pipeline 464.8

RMH21454 Auraria Campus Medium-Voltage Capacity Study Page 8

NEW HOLLY LOT SWITCHGEAR CALCULATED LOAD

The Holly Lot Switchgear is currently slated to have three new loads added: Admin/5th Street transformer moved over from Xcel to campus grid, Ballfield Phase 1 new building, and Public Safety new building.

Admin/5th Street and public safety will go on Circuit 3C/D. Ballfield Phase 1 will have one of their transformers added to Circuit 2C/D and the other two added to the spare Circuit 4C/4D. Based on these calculations, the circuits have capacity for the added load. The switchgear is currently calculated to be over capacity at 610.4A. These load calculations do not include Ballfield Phase 2, as there is no additional capacity to add approximately 269A of additional load between the Arts Switchgear and Holly Lot

Switchgear.

Circuit 1C/D Timing

Metered or NEC

Calc

Load Added (Amps

@13.2kV)

Previous Total (Amps

@13.2kV)

New Total (Amps

@13.2kV)

Current Peak Load Current Metered 121.0 0.0 151.2

Circuit 1C/D NEC Calculated After Current Project Pipeline 151.2

Circuit 2C/D Timing or NEC

Calc

Load Added (Amps

@13.2kV)

Previous Total (Amps

@13.2kV)

New Total (Amps

@13.2kV)

Current Peak Load Current Metered 35.0 0.0 43.8

Tivoli 2027 Metered 57.16 43.8 115.2

Ballfield Ph1 MSB-1 2027 NEC Calc 69.61 115.2 184.9

Circuit 2C/D NEC Calculated After Current Project Pipeline 184.9

Circuit 3C/D Timing or NEC

Calc

Load Added (Amps

@13.2kV)

Previous Total (Amps

@13.2kV)

New Total (Amps

@13.2kV)

Current Peak Load Current Metered 40.4 0.0 50.5

Admin/5th 2026 Metered 37.6 50.5 97.5

Public Safety 2027 NEC Calc 59.6 97.5 157.1

Circuit 3C/D NEC Calculated Current Project Pipeline 157.1

Circuit 4C/D Timing or NEC

Calc

Load Added (Amps

@13.2kV)

Previous Total (Amps

@13.2kV)

New Total (Amps

@13.2kV)

Current Peak Load Current Metered 0.0 0.0 0.0

Ballfield Ph1 MSB-2 2027 NEC Calc 76.75 0.0 76.8

Ballfield Ph1 MSB-3 2027 NEC Calc 122.75 76.8 199.5

Circuit 3C/D NEC Calculated Current Project Pipeline 199.5

RMH21454 Auraria Campus Medium-Voltage Capacity Study Page 9

Holly Lot Switchgear Timing or NEC

Calc

Load Added (Amps

@13.2kV)

Previous Total (Amps

@13.2kV)

New Total (Amps

@13.2kV)

Current Peak Load Current Metered 187.7 0.0 234.7

Admin/5th 2026 Metered 37.6 234.7 281.7

Ballfield Ph1 MSB-1 2027 NEC Calc 69.61 281.7 351.3

Ballfield Ph1 MSB-2 2027 NEC Calc 76.75 351.3 428.0

Ballfield Ph1 MSB-3 2027 NEC Calc 122.75 428.0 550.8

Public Safety 2027 NEC Calc 59.6 550.8 610.4

Holly Lot Switchgear NEC Calculated After Current Project Pipeline 610.4

RECOMMENDATIONS

We recommend that the buildings be connected to circuits as indicated in the calculations above. The public safety building is currently early in design, and it appears that the calculated load will push the

Holly Lot switchgear over its 600A capacity. It is recommended that the public safety project closely monitor their load calculations and consider incorporating additional energy conservation measures if available. If they remain at a level that would put the calculated load on Holly Lot switchgear above 600A, then the building connection could be moved to Circuit 3A/3B on the Arts Building switchgear.

With all these buildings coming online in a short period of time, the calculated spare capacity does not allow the Ballfield Phase 2 project to be added to the campus grid without modification to the existing switchgear and campus distribution. If some of these buildings are completed and occupied, there is potential to get new metered data and to redo the above calculations based on metered data rather than

NEC Demand Calculations. The metered data, however, needs to be taken when the building is fully operational and during peak load times of the year. Based on the timelines of the buildings, their design and construction are likely not a viable option.

If metering of buildings as they come online is not an option, then we recommend studying the most effective option of expanding the campus distribution capacity to be able to connect Ballfield Phase 2.

We recommend that the campus ensure that all metering on the Holly Lot switchgear and the Arts Building switchgear is being recorded in the central metering database. Metering should include the meters on all circuits, as well as the main meters for the switchgear. We also recommend recording 15minute interval data where possible so that the data can be matched up between A and B as well as C and D circuits to get an accurate recording of peak loads on each circuit and switchboard. There is some metering data that has begun to be recorded for Holly Lot circuits for the last six months, but the data is not consistent, with some months being recorded and other months not. As the load on campus starts to increase, it is very important to have accurate and reliable metering.

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