05/09/19

Jennifer Cappeto, Landmark Preservation Manager

Community Planning and Development – City and County of Denver

RE: LPC application for 1019 York Street – Boettcher Memorial Center Renovation

As you know, our first application to the Landmark Preservation Commission was

denied on 05/07/19, due to concerns of the Commission that a proposed louver

on the east side of the building would be detrimental to the historic fabric of the

building.

This louver served an economizer for our HVAC system, and was required by the

new Energy Code, 2015 IECC: C403.3.3. As suggested by the Commission, we

considered other locations for the louver, but are significantly restricted in where

we can run the economizer’s ductwork given the bulky nature of the concrete

structure within the interior of the building, and the low ceilings. Also, finding a

different location for the louver on an exterior wall that would be acceptable to

the commission seemed unlikely. The other suggestion of creating a window well

louver was estimated to be cost-prohibitive due water mitigation requirements

and its more extensive structural implications.

So now we plan to pursue an exemption in the IECC for historic buildings, C501.6,

which will eliminate the requirement for an economizer as well as any new louver

on the exterior of the building. This will also allow us to remove two new exhaust

fans on the roof, which served the economizer. One of them was within the

Landmark designation area, and one was outside of it. We believe this is the best

path forward and faithfully addresses the Commission’s concerns over the new

louver.

We have updated our application packet by removing the louver and its

associated exhaust fans. The application is now limited to the two remaining

exhaust fans, and the work we plan to do to remove the exterior RTU and its

mechanical screen, along with replacing the windows that are currently used for

duct penetrations with matching windows that the Gardens has in storage.

Respectfully Submitted,

David Daniel

Patrick Lee

Micah Holroyd

Davis Partnership Architects

Landmark Preservation Community Planning and Development

201 W. Colfax Ave., Dept. 205 | Denver, CO 80202 www.denvergov.org/landmark

p. 720.865.2709

May 9, 2019 Scott Prisco Building Official City and County of Denver 201 W. Colfax Avenue Denver, CO 80202 Subject: Energy Code Exemption for 1019 York Street Dear Scott: The property located at 1019 York Street at the Denver Botanic Gardens is an individual landmark structure known as the Boettcher Memorial Center designated in 1974. As such, the property is considered a historic building per the 2015 International Energy Conservation Code. Section C501.6 of the 2016 Denver Amendments to the International Energy Conservation Code states:

No provisions of this code relating to the construction, repair, alteration, restoration and movement of structures, and change of occupancy shall be mandatory for historic buildings provided that one of the following applies: c. The local historic preservation authority having jurisdiction provides documentation to the code official with a finding that compliance with that provision would be in conflict with locally adopted historic preservation policies, standards, and guidelines, outlining the specific provisions that are in conflict and how compliance would threaten, degrade or destroy the historic character or features, of the historic form, materials or function of the building.

Denver Landmark Preservation is the local historic preservation authority for the City and City and County of Denver, and we adopted the Secretary of the Interior’s Standards for Rehabilitation as the guiding principles for all historic preservation work in the city; the Design Guidelines for Denver Landmark Structures and Districts are based on the Secretary of the Interior’s Standards. To comply with Section C403.3.3 and C403.3.3.1 of the 2015 IECC, the project team originally proposed to install an air economizer in the building. This would entail installing louvers on the east elevation of the building by cutting through the poured concrete face of the building. On May 7, 2019, the applicant presented the project to the Landmark Preservation Commission, which voted to deny the application. The Commission expressed concern that cutting out a portion of the concrete face of the building would destroy the historic form and fabric of this significant Modernist building. In their motion to deny the application, they cited two design guidelines: guideline 2.60 “Place mechanical, utility and communications equipment to minimize visual impacts on a historic building”; and guideline 2.61 “Install communications, utility and mechanical equipment to minimize damage to historic building fabric.” Following the Commission’s denial of the application, the applicant requests an exemption from Sections C403.3.3 and C403.3.3.1 of the 2015 IECC to allow them not to install air economizers at the building. Landmark Preservation staff would recommend that the project be exempt from this section of the IECC so as not to threaten, degrade or destroy the historic form and fabric of the Boettcher Memorial Center at 1019 York Street. Sincerely, Jennifer Cappeto On behalf of the Landmark Preservation Commission City and County of Denver

DATE:PROJECT NUMBER:COPYRIGHT - DAVIS PARTNERSHIP, P.C.

15523.10

DENVER BOTANIC GARDENS - BOETTCHER MEMORIAL CENTER

RENOVATION

Extent of Landmark Designation 04/19/19

1

7

1

7

35' - 9 3/8"

NEW EXHAUST FAN (EF-1)REPLACING EXISTING

EXISTING DUCTWORK TO REMAIN

MAIN ENTRANCE

EXISTING RTUs TO REMAIN

NEW EXHAUST FAN (EF-2)ON NON-LANDMARK DESIGNATED ROOF

DATE:PROJECT NUMBER:COPYRIGHT - DAVIS PARTNERSHIP, P.C.

15523.10

DENVER BOTANIC GARDENS - BOETTCHER MEMORIAL CENTERRENOVATION

Roof Plan 05/09/19

1" = 20'-0"1BOETTCHER - MECHANICAL ROOF PLAN

EF-1

DATE:PROJECT NUMBER:COPYRIGHT - DAVIS PARTNERSHIP, P.C.

15523.10

DENVER BOTANIC GARDENS - BOETTCHER MEMORIAL CENTER

RENOVATION

Building Section 05/09/19

1/16" = 1'-0"1EAST - WEST BUILDING SECTION

BOETTCHER - L1109' - 7 1/32"

BOETTCHER - LL99' - 7 1/32"

0

3' -

10

1/2

"4

' -

10

1/2

"

12

2

12

3

INSTALL SALVAGED

ALUMINUM WINDOWS

FROM STORAGE THAT

MATCH EXISTING

WINDOWS ON THIS

ELEVATION

1' -

6"

3 1/2"

1' - 8"

0

SET SALVAGED WINDOW BACK FROM EXTERIOR

FACE OF CONCRETE WALL TO MATCH SETBACK OF

OTHER EXISTING WINDOWS

EXTERIOR FACE OF EXISTING CONCRETE

WALL BEYOND SECTION CUT

3 1/2"

0

SET SALVAGED WINDOW BACK FROM EXTERIOR

FACE OF CONCRETE WALL TO MATCH SETBACK OF

OTHER EXISTING WINDOWS

EXTERIOR FACE OF EXISTING CONCRETE

WALL BEYOND SECTION CUT

3 1/2"

1' - 8"

EXTERIOR FACE OF

EXISTING CONCRETE

WALL CUT BY

SECTION

DATE:PROJECT NUMBER:COPYRIGHT - DAVIS PARTNERSHIP, P.C.

15523.10

DENVER BOTANIC GARDENS - BOETTCHER MEMORIAL CENTER

RENOVATIONWall Section at New Windows inExisting Opening 04/19/19

1/2" = 1'-0"1

Wall Section at New Windows in ExistingOpenings

1 1/2" = 1'-0"2Window Head

1 1/2" = 1'-0"3Window Sill

OVERALL HEIGHT MAY BE GREATER DEPENDING ON MOTOR.

19.00 SQ

1.75

23.70

Ø 24.40

35.70

(12.00)

Model: G-103-VGDirect Drive Centrifugal Roof Exhaust Fan

DimensionalQuantity 1

Weight w/o Acc's (lb) 35

Weight w/ Acc's (lb) 52Roof Opening (in.) 14.5 x 14.5

PerformanceRequested Volume (CFM) 1,000

Actual Volume (CFM) 1,000

Total External SP (in. wg) 0.75

Fan RPM 1709

Operating Power (hp) 0.23

Elevation (ft) 5,430

Airstream Temp.(F) 70

Air Density (lb/ft3) 0.061

Tip Speed (ft/min) 4,978Static Eff. (%) 50

MotorMotor Mounted Yes

Size (hp) 1/4

Voltage/Cycle/Phase 115/60/1

Enclosure ODP

Motor RPM 1725

Windings 1FLA (Amps) 2.85

Notes:All dimensions shown are in units of in.*NEC FLA - based on tables 430.248 or 430.250 ofNational Electrical Code 2014. Actual motor FLA may vary,for sizing thermal overload, consult factory.LwA - A weighted sound power level, based on ANSI S1.4dBA - A weighted sound pressure level, based on 11.5 dBattenuation per Octave band at 5 ft - dBA levels are notlicensed by AMCA InternationalSones - calculated using AMCA 301 at 5 ft

Sound Power by Octave BandSoundData 62.5 125 250 500 1000 2000 4000 8000 LwA dBA Sones

Inlet 73 76 73 69 61 58 54 48 70 59 9.3

04/15/2019Printed Date: 16098-DBG-Boettcher RenovationJob:

EF-1Mark: G-103-VGModel:

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