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ENVIRONMENTAL ASSESSMENT

THOMAS EDISON NATIONAL HISTORICAL PARK

BASIS OF DESIGN REPORT

SCHEMATIC DESIGN

SEPTEMBER 15, 2025

Margaret Breuker @david_vago@nps.gov Please view this document. You can also add comments.

John G. Waite Associates, Architects pllc 384 Broadway, Albany NY 12207

225 Broadway, Suite 1515, New York, NY 10007

GLENMONT

THOMAS EDISON NATIONAL

HISTORICAL PARK

ENVIRONMENTAL ASSESSMENT

TASK ORDER: 140P4520F0043

SCHEMATIC DESIGN

BASIS OF DESIGN REPORT

SEPTEMBER 15, 2025

GLENMONT

THOMAS EDISON NATIONAL HISTORICAL PARK

ENVIRONMENTAL ASSESSMENT

for NATIONAL PARK SERVICE

Margaret Breuker, NPS-Historic Architecture, Conservation, and Engineering (HACE)

David Bittermann, NPS-HACE

David Vago, NPS-Thomas Edison National Historical Park (EDIS)

Beth Miller, NPS-EDIS

Timothy Stauffer, NPS-EDIS

JOHN G. WAITE ASSOCIATES, ARCHITECTS pllc

John G. Waite, FAIA, FAPT

Nancy Rankin, AIA, LEED-AP

Preme Chaiyatham

Brandy Nguyen

Anne E. Weber, FAIA, FAPT

KOHLER RONAN, CONSULTING ENGINEERS

Robert Hedman, PE, LEED AP BD+C, WELL AP, Fitwel Amb, CPHD, LFA, Partner

Jerry Manavalan, Associate

GLENMONT, THOMAS EDISON NATIONAL HISTORICAL PARK, BASIS OF DESIGN REPORT

CONTENTS

Executive Summary����������������������������������������������������������������������������������������������������� 1

Mechanical System Recommendations�������������������������������������������������������������������� 4

Alternative 2����������������������������������������������������������������������������������������������������������� 5

Alternative 3����������������������������������������������������������������������������������������������������������� 5

Alternative 5����������������������������������������������������������������������������������������������������������� 6

Architectural And Landscape Recommendations ������������������������������������������������� 8

Architecture����������������������������������������������������������������������������������������������������������� 8

Cultural Landscape��������������������������������������������������������������������������������������������� 18

Recommended Work������������������������������������������������������������������������������������������������ 21

All Alternatives����������������������������������������������������������������������������������������������������� 21

Mechanical Alternative 2������������������������������������������������������������������������������������ 22

Mechanical Alternative 3������������������������������������������������������������������������������������ 22

Mechanical Alternative 5������������������������������������������������������������������������������������ 22

Other Recommendations����������������������������������������������������������������������������������� 22

Cost Study������������������������������������������������������������������������������������������������������������������ 24

Appendix A - Floor Plans

Appendix B - System Alternative Narrative

Appendix C - System Drawings

Appendix D - Load Calculation

Appendix E - Geothermal Loop Site Drawing

Appendix F - Window Insert Cutsheet

Appendix G - Awning Estimate

Appendix H - Schematic Cost Study

SEPTEMBER 15, 2025 • 1

EXECUTIVE SUMMARY

This Basis of Design Report is a deliverable of the Schematic Design Phase of Environmental Assessment for Glenmont Mansion, and presents recommendations for three alternatives for improvements to the climate control systems to provide an enhanced conservation environment for the collections and historic structure.

Architectural improvements for the building envelope are also recommended both to correct deficiencies that may threaten conservation efforts and to facilitate better climate control.

The National Park Service (NPS) engaged John G. Waite Associates, Architects PLLC (JGWA) in October 2020 to perform an environmental assessment for Glenmont, the private estate of Thomas Edison, and subsequent schematic design for environmental control systems and associated building improvements. Located within Llewellyn Park in West Orange, New Jersey, Glenmont Mansion is listed on the National Register of Historic Places and is a part of the Thomas Edison National Historical Park. The JGWA team includes Kohler Ronan Consulting Engineers (KR) for assessment of mechanical and electrical systems; and Wendy Jessup and Associates, Inc. (WJ&A), for evaluation of the conditions of the museum’s collections and identification of where environmental conditions may be affecting their conditions. The house is located in Climate Zone 4A, mixed-humid, with cold winters and hot summers with elevated humidity. A field investigation done in late 2020 resulted in a Field Investigation Report, dated March 2021. The report evaluated the building fabric and envelope, existing mechanical systems, museum collections, and building operations in order to indicate potential deficiencies in the interior environment of the historic house museum and provide recommendations for improvement.

Following the Field Investigation Report, a two-year environmental monitoring program was performed between December 2021 and December 2023 to assess the interior localized climate and air quality trends. Additionally, an airside system balance was recorded to evaluate the airflow for the air handling units, supply, and return grills. The collected environmental data included interior temperatures, relative humidity, dewpoint temperature, and indoor air pollutants. However, Wi-Fi connectivity issues at Glenmont led to this data being impractical for use in evaluating the potential impact of pollutants on the collection and building fabric.

The May 2024 Environmental Data Monitoring Report includes analyses of the collected data to evaluate the efficacy of the current HVAC system, to assess the impacts of the existing environment on the collections, and to understand the limits and contributions of the building envelope relative to the mechanical system and collections; and recommendations for HVAC system upgrades, collections management, and building envelope improvement.

The existing HVAC and controls system appears to be intended to operate on a range of 70 - 75 degrees F and a 58 degree F dewpoint. However the monitoring found the actual operating conditions were 45 – 85 deg F and 12 – 85% relative humidity (RH).

While interior temperature was most often within the desired range, the relative humidity fluctuated greatly in many locations around the building, indicating that humidity control must be addressed in system improvements. These discrepancies can be attributable both

SEPTEMBER 15, 2025 • 2

to control system deficiencies as well as equipment simply being incapable of maintaining these conditions at this time. As a result of the testing and building and collections evaluation, a revised RH range of 35 – 65% is proposed, with a dewpoint of 27 – 65 degrees F. To allow for better seasonal control, different summer and winter setpoints are recommended: 51 – 69 degrees and 30 – 40% RH in winter; and 66 - 80 degrees and 50 – 60% RH in summer. The transition from one setpoint to the other should happen gradually, over a period of at least a month to allow for acclimation of building materials and collections objects. Options for control of humidity include increased cooling capacity and dehumidification for elevated humidity, and humidification and temperature reduction for low humidity. NPS subsequently determined it does not want to provide humidification, so no alternative including this was carried forward.

The Environmental Data Monitoring Report presented five HVAC system configurations as being responsive to the conditions found, and appropriate for the building and site.

After review of these alternatives with the NPS, including staff from Thomas Edison National Historical Park (EDIS) and from Historic Architecture, Conservation, and Engineering Center (HACE), three – Alternatives 2, 3, and 5 – were selected for further development in the current Schematic Design Phase. JGWA and KR made a site visit on April 1st, 2025 to refine recommendations in each selected alternative.

These Alternatives are:

• Alternative 2: The existing system with new controls throughout to provide improved regulation of conditions.

• Alternative 3: The existing system with new controls and dehumidification added to the air distribution.

• Alternative 5: The existing system with additional air conditioning capacity provided by a chiller, Dedicated Outside Air System (DOAS) units, and circulating hot and chilled water for fancoils located at dispersed locations around the house

Alternative 2 has the least impact on the structure, cultural landscape, and visitor experience, but will result in a wide range of temperature and relative humidity and so limited improvement in conservation conditions for the collections and building fabric is likely to be achieved.

Alternative 3 improves summer humidity control, with different levels of impact on the building fabric, cultural landscape, and visitor experience.

Alternative 5 creates the best control of temperature and humidity, with the greatest physical impact on the building fabric, cultural landscape, and visitor experience.

No alternative studied brings the low (winter) humidity into the recommended range.

Humidification would be required to address this issue.

Other alternatives were not pursued for a variety of reasons:

Alternative 1 – Addition of DOAS units, humidification, and a Variable Refrigerant Flow (VRF) system – would provide good control of environmental conditions including both summer and winter humidity, but with a significant maintenance commitment for the humidification and life-cycle and fire safety concerns with the VRF system.

Humidification also increases the likelihood of creating the conditions for condensation on collection items and building fabric. NPS determined that they did not want to provide humidification at Glenmont.

SEPTEMBER 15, 2025 • 3

Alternative 4 – Addition of DOAS units and a VRF system – would not provide significantly better humidity control than the selected alternatives, and has the life-cycle and fire safety concerns associated with the VRF system.

The comprehensive schematic design approach to the mechanical upgrades proposed at Glenmont also includes architectural work related to the installation of improvements to the mechanical and electrical systems and passive building envelope interventions aimed at improving conditions for the collections and building fabric. Following the principle to avoid adverse effects rather than mitigate them, the architects and engineers will work closely together to minimize the impact of the system improvements on character-defining features of the building and landscape, and on significant building finishes. Architectural improvements will include exterior awnings and window curtains and shades to reduce visible light and solar heat gain through shading;

additional storm window panels to help limit air infiltration and ultra-violet and infra-red light; replacement of floor canvases at porches; foundation and roof drainage and window repairs to reduce moisture transport and air infiltration into the structure; and maintenance at water-shedding elements such as roofs, gutters, and downspouts.

While this task order does not include a formal Class C estimate, it appears that Alternative 2 would be the least expensive, and Alternative 5 the most expensive. Within Alternative 3, Alternative 3B would be the least expensive, with Alternative 3C the most.

A budget estimate for the awnings is included in Appendix G. (Note that this estimate assumes general performance fabric for estimating purpose. Appropriate color and pattern will need to be updated per a recommendation included in the following sections.) This improvement, as well as other recommended architectural work, could be done as separate Park projects, and do not necessarily need to be a part of the HVAC upgrade project.

SEPTEMBER 15, 2025 • 4

MECHANICAL SYSTEM RECOMMENDATIONS

The Data Monitoring Report included five alternatives for a mechanical system that would address the environmental conditions at Glenmont, which were narrowed down to three for the Schematic Design phase: Alternatives 2, 3, and 5.

The desired range of temperature and relative humidity is 55 – 80 deg F and 30 - 65% RH.

A site visit was conducted on April 1, 2025 for JGWA and KR to review site conditions with NPS to develop scope details for the three selected alternative systems. Existing mechanical and electrical systems were reviewed, mainly in the basement and attic.

Recent maintenance projects were also reviewed. Possible spaces for additional fan coil units were surveyed (Alternative 5,) primarily on the second floor. Information on architectural elements that have an impact the environmental conditions was discussed, including historic awnings and the recently installed window interior inserts.

Additionally, exterior locations for on-grade equipment and for intake and exhaust through basement openings were investigated.

A summary of the developed alternatives is provided in this section. Comprehensive descriptions for each alternative can be found in Appendix B. Table 1 demonstrates similarities and differences among the 3 alternatives.

All alternatives include the following assumptions:

• Existing geothermal loops will be utilized and connected to new water-to-water heat pump units. From existing documents and reports, the cooling capacity of the system is about 15 to 18 tons, calculated from the number and depths of the wells, the capacity of the existing water-to-water heat pumps, and the sizes of the two existing air handling units.

• Existing ductwork will remain and be insulated where feasible, generally at currently exposed areas in the basement and attic.

• Existing control system will be replaced, including valves, sensors, thermostats, and actuators.

• To reduce cooling load and light levels, historic awnings will be reintroduced or new window shades provided.

• The building envelope will be air-sealed where feasible.

SEPTEMBER 15, 2025 • 5

• Existing heat pumps and piping will be replaced in the mechanical room. Provide five new water-to-water heat pumps to generate hot and chilled water for the air handling units (Alternatives 2 and 3) or DOAS units (Alternative 5.)

• Provide one shell-and-tube heat exchanger.

• The existing boiler will remain.

• Provide new circulating pumps for the geothermal loop and the heat pumps.

• The system will be rebalanced and commissioned to ensure that it operates as specified.

• A service contract for maintenance is recommended.

Note that there will be downtime for the mechanical system during the removal and installation of equipment. The approximate duration of the equipment replacement is three months. Temporary heating or cooling equipment can be implemented to maintain the environmental interior conditions, depending on the time of the year. The units can be located at grade, with temporary water hoses and flexible ductwork connected to them through basement openings.

ALTERNATIVE 2

Alternative 2 maintains the current system design with replacement in kind of the existing equipment. New heat pumps provide limited capacity for control of humidity in the summer season. The existing geothermal loop, existing boiler, and new heat pumps may have the capacity to maintain an interior condition of 50°F - 85°F and 12%RH - 85%RH.

The expected relative humidity range is below the target range in the winter and above the target range in the summer.

While this alternative poses the most minimal physical impact on the structure and cultural landscape and results in improvements over the existing conditions, this alternative will result in a wide range of temperatures and humidities similar to the existing conditions which may affect artifact conservation. This alternative does not require upgrade of the existing electrical service.

ALTERNATIVE 3

Alternative 3 includes replacement in kind of most existing equipment, and adds a side-stream dehumidifier to each existing air handling unit, allowing a greater level of summer humidity reduction than increased cooling capacity alone. The dehumidifier units would be located adjacent to the air handlers. This system may have the capacity of maintaining an interior condition of 50°F - 85°F and 12%RH - 60%RH, not providing winter season control of low humidity within the desired range. The existing electrical system does not require an upgrade for this alternative.

Dehumidifiers produce / require heat as part of their operation. To handle this generated heat, there are three dehumidifier sub-alternatives available:

• A - Provide two dehumidifiers, one at each existing air handler, with remote heat dissipation. Heat would be exhausted through remote condensers outdoors at grade, SEPTEMBER 15, 2025 • 6 which can be located at a distance from the dehumidifiers, possibly near the visitor parking lot or geothermal well field, connected to the dehumidifiers with underground refrigerant lines. This sub-alternative has the most physical impact on the surrounding landscape, including the visual effect created by the remote condensers and the landscape and archaeological impact of 400'-500' of trenchwork. The noise generated by the condenser is also an impact on the cultural landscape.

• B - Provide two dehumidifiers without remote heat dissipation. Heat will be dissipated directly at the site of the dehumidifier, i.e. into the basement or attic. While this alternative poses the least impact on the landscape and architecture, the cooling capacity of the units will be decreased slightly, as the heat of the compressors is put back into the stream and not rejected to the exterior.

• C - Provide two dehumidifiers each containing an integral gas-fired hot water heater with flues routed through a basement window panel at the same location as the existing central heating boiler. Intake and exhaust ductwork will be routed to basement window openings also. While impact on the landscape in this sub-alternative will be limited to additional basement window modifications, two additional make-up and exhaust ducts, flue piping, hot water piping, and gas piping will be required in the basement. There would be a similar impact of piping and ductwork in the attic.

ALTERNATIVE 5

Alternative 5 replaces all air handling units with DOAS units to provide dehumidification, ventilation, heating, and limited cooling. This system also provides positive building pressure, limiting air infiltration to allow better temperature and humidity control.

A remote air-cooled chiller (outdoor unit) will be provided. The chiller can be located in the vicinity of the well field and visitor parking, 400 - 500 feet away from the house, and connected with underground water piping. This alternative requires an electrical system upgrade to 800A 3-phase service.

17 fan coil units and 40 supply grilles will be provided as follows:

• Seven horizontal fan coil units will be mounted in the basement and ducted to new and existing first-floor floor grilles.

• Four vertical fan coil units will be mounted in second-floor closets and ducted to new sidewall grilles.

• Six horizontal fan coil units will be mounted in the attic and ducted to third-floor ceiling grilles.

Note that the fan coil units on the second floor will need new piping – supply, return, and condensate return – running to them from the basement. Penetrations on the existing second-floor closet walls and undercuts at closet doors will need to be provided to install ducts and grilles for the fan coil units. Sound deadening will also be provided at doors and walls. Additional floor-mounted grilles for both return and supply air will need to be installed on the first floor and ceiling grilles for supply and return air on the third floor.

The shape and dimensions of each grille will vary to fit the existing element in which they are located, but the net area will be determined by the amount of air required and noise considerations.

SEPTEMBER 15, 2025 • 7

This system, comprising five new heat pumps, a new air-cooled chiller, two DOAS units, and 17 fancoil units has the capacity to maintain an interior condition of 60°F - 75°F and 12%RH - 60%RH, providing the most controlled and evenly distributed conditioned air in the spaces out of all the alternatives, although the low-end humidity is outside the target range. However, this alternative also has the greatest impact on the building and site out of all 3 proposed alternatives, including the exterior chiller at grade and additional penetrations on the floors and walls throughout the interiors of the structure.

Table 1. Comparison among three alternatives for the systems.

Alternative 2 Alternative 3 Alternative 5

50-85 F 50-85 F 60-75 F

12-85% RH 12-60% RH 12-60% RH

Remain Remain Provide (2) DOAS units

Provide 54 Provide 54 Provide 54

Provide 6 Provide 6 Provide 6

Replace Replace Replace

Remain Remain Remain

Yes Yes Yes

Remain Remain Remain

Provide 6 Provide 6 Provide 6

Provide 5 Provide 5 Provide 5

Provide 1 Provide 1 Provide 1

Remain Remain Remain

Option A Provide 2 with remote condensers

Option B Provide 2

Option C Provide 2 with outdoor air, exhaust air, and reactivation heat.

Provide (1) condensing gas fired boiler

Provide (1) Air cooled chiller Provide (2) primary chilled water pumps Provide (1) 5-gallon expansion Provide (1) 140-gallon buffer tank Provide (1) air separator

Provide (7) horizontal fan coil units in the basement Provide (4) vertical fan coil units on the 2nd floor Provide (6) horizontal fancoil units in the attic

Provide (40) grilles

About 400' for Alternative 3A About 400'

Remain Remain Provide 800 amp 3-phase service and distribution equipment

Shell-and-Tube Heat Exchanger

Boiler and Hot Water Pump

Dehumidifier

Ductwork

Service Contract

Geothermal

Inline Pump

Water-to-Water Heat Pump

Temperature

Relative Humidity

Air Handling Units

Awnings

Controls

Window Inserts

Chiller

Fan Coil Units

Grilles

Trenching

Electrical System

SEPTEMBER 15, 2025 • 8

ARCHITECTURAL AND LANDSCAPE

RECOMMENDATIONS

To preserve the historic fabric and character-defining features of Glenmont and its surrounding landscape, the team followed the Secretary of the Interior's Standards for the Treatment of Historic Properties in making recommendations. Determinations of contributing features in the landscape are made from the National Park Service 2011 Cultural Landscapes Inventory. Character-defining features of the building are referred from the 1998 Historic Structure Report Part 1 and 2017 Historic Structure Report Part 2.

ARCHITECTURE

Architectural work associated with the environmental control improvement project includes certain envelope modifications, maintenance tasks, and alterations necessary to integrate the systems into the building with minimum impact on the integrity of the site.

The three alternatives for the mechanical system pose varying impacts on the structure.

These impacts should be considered in the selection of a preferred approach.

INTEGRATION OF SYSTEMS INTO ARCHITECTURE

The system design primarily focuses on exhibition and storage spaces on the first, second, and third floors. The recommended achievable temperature and relative humidity ranges take into consideration collections and material conservation, and users’ comfort. While the achievable ranges of these conditions vary depending on the alternative selected, careful consideration is taken into the system design to prioritize conditioning more sensitive spaces, which are those that are planned for exhibits with objects and finishes directly associated with the Edison family occupancy of the house. Collections items may be stored in microclimate conditions, but those on exhibit in a historic house museum are subject to the prevailing environment. These spaces include all rooms on the first and second floors, except the Conservatory Room (101). See A1.3 in Appendix A. For the third floor, rooms selected for future exhibits take priority. These include Master Hall (312), Sewing Room (305), Bedroom 1 (306), Bedroom 2(307), Bedroom 3 (308), Bedroom 4 (309), Bedroom 5 (310), and Service Hall (311). See drawing A1.5 in Appendix A.

Alternative 2 is the least invasive of the three alternatives, since the existing system will be utilized with limited modifications not affecting the visible devices in public areas.

For Alternative 3, central dehumidifiers will be added to the existing system. Devices in the public areas of the building will not be altered. The dehumidifier units themselves will be located in the basement and attic. There are 3 sub-alternatives available for this equipment. Sub-alternative A requires outdoor remote condensers at grade (measuring roughly 70x65x35 inches), which can be located 400 feet or more from the house.

Locating this equipment on the Johnson-Tilney property near the visitor parking and geothermal wellfield minimizes both visual and acoustical impacts on the structure.

Sub-alternative B does not require any outdoor equipment or alteration of devices in

SEPTEMBER 15, 2025 • 9

significant spaces. Sub-alternative C requires ducts and piping through the basement and attic for outdoor and exhaust air. These ducts can be terminated at windows in the basement and at shielded locations at the attic. Windows that can receive these ducts, considering their distances from the units and exterior appearance of the structure, are 002, 012, and 013. Window 013 already has a flue for the existing boiler, making it a good candidate for the exhaust air louver and flue, while window 002 is concealed behind existing shrubs, making it possible to install the intake air louver. See drawing A1.2 in Appendix A.

Alternative 5 requires an air-cooled chiller at grade, measuring 114x50x85 inches. As discussed in the previous section, it can be situated 400 to 500 feet away from the house, which minimizes its impact on the site. Because this alternative requires multiple fan coil units in the interior spaces, careful consideration should be given to the placement of these units, specifically on the second floor. Closet spaces can be utilized to conceal the ductwork and piping. Penetrations in the existing floors and walls are needed to install additional pipes and grilles. Placement of fans in or near program spaces will increase noise levels, although sound deadening measures can be employed to mitigate this increase.

BUILDING ENVELOPE MODIFICATIONS

Since the complex forms, details, and use of materials are part of the character-defining features (CDFs) of the Queen Anne style structure, any modification to the building envelope should not alter these elements. To improve the environmental conditions of the interior spaces and lessen the heat loads on the mechanical system, certain repairs and restoration are recommended, while ensuring the integrity of the house.

To prevent water infiltration into the basement of the building, which will tend to increase the humidity in the upper floors, particularly the first floor, the existing floor canvas system at the front porches should be replaced, as it is at the end of its service life, evident in the loss of materials in localized areas (Figure 1 and 2). Openings in the building, such as a former coal delivery chute below the front porches, should be routinely checked to ensure that they are closed and watertight (Figure 3). The Park is taking on other preventive maintenance projects such as foundation and roof drainage and window repairs to reduce moisture transport and air infiltration into the structure.

To mitigate the summer solar gain through the exterior envelope, seasonal installation of awnings is recommended. Apart from reducing the heat gain at openings, the historic appearance of the structure will be restored, as recommended in the 1998 Historic Structure Report. Openings to receive awnings are identified from information in the 2017 Historic Structure Report Part 2 and historic photos. Floor plans indicating locations of awnings are included in Appendix A. Archival documents show that the pattern is striped, with deeply scalloped edges (Figure 4). However, there is no record on the color of the fabric. Thus, careful selection should be made from typical color schemes of the period. Repositories of trade catalogues, such as Avery Library at Columbia University or the APT Building Technology Heritage Library should be consulted.

Existing hardware, which can still be found on some openings, should be evaluated and replicated (Figures 5-7). Contract service should be included to install the awnings in late spring and remove for storage in early fall. See Appendix A.

SEPTEMBER 15, 2025 • 10

The Park recently installed interior secondary glazing inserts at almost all windows (Figure 8). The inserts help prevent drafts that may infiltrate gaps in the openings, as well as filter out ultraviolet light, which is detrimental to the collections. Approximately 8 openings have not received the inserts due to their locations or irregular shapes, along with being exits or having mechanical equipment installed. Moreover, the Park did not install the inserts at the openings in the Conservatory (101), since there may be a reconstruction project in the future for this section of the building and there are currently no sensitive collections being placed in this area (Figure 9). To realize the full potential of the inserts in regulating the interior environmental conditions, it is recommended that the remaining openings, and the to-be-reconstructed Conservatory, receive similar treatment as others. (Information on the inserts is included in Appendices A and F.) Weatherstripping at doors will also serve to reduce infiltration, which will make temperature and humidity control easier.

Currently, most of the spaces with exhibits have curtains that limit light exposure and help offset the solar heat gain in the summer and heat loss in the winter (Figure 10). It is recommended that these curtains be maintained and replaced when they reach the end of their service life. Blackout curtain liners should be considered on large openings, especially on the south, east, and west elevations, provided that they do not interfere with the interpretation of the spaces. Many rooms on the third floor have modern shades installed that are incongruous to the period of significance (Figure 11). Period-appropriate curtains should be installed when these spaces are turned into exhibit spaces. Moreover, certain windows in non-exhibit spaces on the third floor and attic appear to have temporary shades, while others do not have any at all (Figures 12-14).

It is recommended these spaces be provided with shades that have the proper shading coefficient to address heat gain, while offering some visible light transmittance to illuminate the rooms.

Figure 1. Existing floor canvas system at front porches. (JGWA, 2025)

SEPTEMBER 15, 2025 • 11

Figure 2. Loss of material at edges of the floor canvas. (JGWA, 2025)

Figure 3. Unprotected opening in the basement can be a source of water infiltration into the space, increasing humidity in the building. (JGWA, 2025)

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Figure 4. Historic awning with striped fabric and scalloped edge. (HABS, 1930)

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Figure 5. Existing awning hardware still remains on certain locations. (JGWA, 2025)

Figure 6. Existing awning hardware should be assessed to determine its re-usability and replication. (JGWA, 2025)

SEPTEMBER 15, 2025 • 14

Figure 7. Existing awning hardware should be assessed to determine its re-usability and replication. (JGWA, 2025)

Figure 8. Most windows have interior inserts installed, which help with air infiltration and UV light filtering.

(JGWA, 2025)

SEPTEMBER 15, 2025 • 15

Figure 9. The openings in the Conservatory do not have the interior inserts, as a future reconstruction project is expected. (JGWA, 2025)

Figure 10. Rooms with exhibits have curtains installed. (JGWA, 2025)

SEPTEMBER 15, 2025 • 16

Figure 11. Several spaces on the third floor have modern shades installed. Period-appropriate curtains should be installed when these spaces are turned into exhibit spaces. (JGWA, 2025)

Figure 12. Some of the windows on the third floor and attic appear to have temporary shades that do not help much with the interior environmental condition improvement. These shades should be replaced with fabric that has proper heat and light transmission properties. (JGWA, 2025)

SEPTEMBER 15, 2025 • 17

Figure 13. Some windows in the attic do not have shades installed. (JGWA, 2025)

Figure 14. Some of the windows on the third floor and attic appear to have temporary shades that do not help much with the interior environmental condition improvement. These shades should be replaced with fabric that has proper heat and light transmission properties. (JGWA, 2025)

SEPTEMBER 15, 2025 • 18

CULTURAL LANDSCAPE

Glenmont Estate is a 15.67-acre property situated within Thomas Edison National Historical Park. The property is significant for its associations with American inventor and businessman Thomas Edison, its contribution to the Llewellyn Park Historic District, its central Queen Anne-style house, and its landscape design. The house is surrounded by an expansive lawn scattered with several service buildings, pathways, and vegetative features originating from the Estate’s period of significance, 1857-1931. Though some changes have occurred since 1931, the landscape still retains its overall integrity through the preservation of its plantings, viewsheds, small-scale structures, and spatial relationships with the main house.

The Glenmont Estate landscape is organized into seven spaces: the west (back) lawn, front lawn, south (lower) lawn, laundry yard, woodland, service area, and Johnson-Tilney property (Area highlighted in purple on Figure 15). The first six spaces are considered contributing features to the Estate’s historic character. The non-contributing status of the Johnson-Tilney property and its proximity to the Glenmont House make it a suitable parcel for new mechanical equipment on grade (condensers, Alternative 3A; air-cooled chiller, Alternative 5).

The Johnson-Tilney property contains the visitor parking lot and a mix of trees and shrubs, all of which are non-contributing features. All other vegetation on the estate is considered a contributing feature and should be protected and preserved during sitework. This includes the main house’s foundation plantings, the planting bed within the main driveway, the trees and shrubs within the laundry yard, and the hemlock trees lining Honeysuckle Avenue. The driveways, walkways, and garden paths around the Mansion, excluding those within the Johnson-Tilney property, are also contributing features to be maintained.

Underground piping for refrigerant or chilled water would be required for Alternatives 3A and 5. Trenchwork and sitework should avoid any contributing structures and tree root zones between the main house and new equipment, including the hose house (Figure

16) and historic clothesline posts in the laundry yard (Figure 17). Sitework should also avoid the pump house located north of the main house (Figure 18). To be least invasive to the significant features on the site and minimize the disturbance on the archeologically sensitive areas, the trenchwork can follow the existing geothermal supply and return route, which has been previously disturbed, as shown in Appendix E.

Any new equipment on the Johnson-Tilney property should not alter the viewshed from Glenmont to the east.

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Figure 15. Organization of spaces at Glenmont Estate. The area highlighted in purple is the Johnson-Tilney property.

(OCLP, 2009)

Figure 16. (Left) Historic hose house. (JGWA, 2025)

Figure 17. (Right) Historic wooden clothes line posts. (OCLP, 2009)

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Figure 19. Glenmont landscape site diagram with 400-foot radius for potential new mechanical equipment location highlighted in red. (JGWA, 2025)

Figure 18. Historic pump house. (JGWA, 2020)

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RECOMMENDED WORK

The improvement of the interior environmental condition at Glenmont will be beneficial to the collections, users' experience, and overall preservation of the structure at large.

To achieve this, a combination of architectural restoration and system alternatives are recommended. Since there are three alternatives for the building systems under consideration, the following recommendations are categorized as such, with some overlapping items across the alternatives.

ALL ALTERNATIVES

ARCHITECTURAL

• Replace the floor canvas system on the two front porches.

• Provide awnings in their historic locations. Existing hardware should be evaluated and replicated. Fabric pattern and fringe detail should follow those in historic photographs.

Since there is no evidence on the color of the fabric, the selection should be period-appropriate.

• Provide interior inserts at all windows that do not have them currently.

• Provide period-appropriate curtains on the third floor, especially in the spaces that will be turned into exhibits.

• Provide shades with proper thermal and light transmission properties at windows in non-exhibit spaces on the third floor and attic.

• Provide blackout curtain liners at large openings, especially on the south, west, and east elevations.

• Provide weatherstripping at exterior doors.

MECHANICAL

• Connect the existing geothermal loops to new water-to-water heat pump units.

• Insulate the existing ductwork where feasible, generally where it is exposed in the basement and attic.

• Replace the existing control system in its entirety, including valves, sensors, thermostats, and actuators.

• Replace the existing heat pumps and piping in the mechanical room.

• Connect the existing boiler to new equipment.

• Replace circulating pumps for the geothermal loop and heat pumps.

• Balance and commission the system to ensure that it operates as specified.

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• Provide temporary air handling units and associated components during the removals and installations of new equipment to ensure that the interior environmental conditions are controlled to minimize adverse effects on the collections.

MECHANICAL ALTERNATIVE 2

• This alternative includes only common mechanical and architectural work noted above.

MECHANICAL ALTERNATIVE 3

• Provide dehumidifiers associated with the two existing air handlers.

• Alternative 3A – install the outdoor equipment for the dehumidifiers on the Johnson- Tilney property and at the least conspicuous location. Install a metal picket fence and gate around the equipment for security, with vegetative screening as well. Trenchwork should follow the existing route for the geothermal supply and return. Implement arborist and archeological monitoring during trenching.

• Alternative 3C - Use the existing opening where the flue for the existing boiler terminates for required exhaust duct and flue terminations. The intake air duct should terminate at an inconspicuous window opening in the basement.

MECHANICAL ALTERNATIVE 5

• Provide a new system replacing existing air handlers with DOAS units, and providing an air-cooled chiller and with associated fan coil units for heating and cooling.

• Install the chiller on the Johnson-Tilney property and at the least conspicuous location. Provide a metal picket fence and gate around the equipment for security, with vegetative screening as well. Trenchwork should follow the existing route for the geothermal supply and return. Implement arborist and archeological monitoring during trenching.

• Provide piping routes, duct routes, and wall, ceiling, and floor penetrations for air grilles in a way that is the least invasive to the existing fabric of the structure.

OTHER RECOMMENDATIONS

• Implement a service contract for maintenance of mechanical systems.

• Develop an operation and maintenance plan to ensure that openings on the structure are closed and watertight to prevent water and air infiltration into the spaces.

• Continue research efforts to find more information on the historic awnings in available archival materials.

• Execute a service contract with a professional awning installer to install the awnings in spring and remove for storage in fall.

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• Perform blower-door testing to evaluate the extent of air infiltration at the building envelope.

• Undertake a Value-Based Decision Making process to select mechanical and electrical system alternatives as well as on-site vs. off-site collections storage approach.

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COST STUDY

Because a full Class C estimate is not included in the scope of this project, JGWA worked with Nasco Construction Services to develop a Schematic Cost Study for selected equipment and features of the alternatives. These costs will be used by the NPS in a value methodology process to identify a preferred alternative. They cannot be taken as a complete construction cost estimate for the project. Standard construction markups such as General Conditions, contractor overhead and profit, and bonds and insurance have been included as shown, but other NPS typical markups such as the location factor and contracting factor have not been included. The numbers do not include any escalation, and are as of August, 2025.

SUBJECT: SUMMARY - ALL OPTIONS EST. NO: 25-0153

PROJECT: GLENMONT HVAC EST. BY: BA

LOCATION: THOMAS EDISON NATIONAL HISTORICAL PARK CHKD. BY: EH

TYPE EST.: SCHEMATIC COST STUDY DATE: 07/28/2025

CLIENT: JOHN G. WAITE ASSOCIATES REV. DATE: 8/8/2025

GSF: 1,458

ALTERNATIVE 2 3A 3B 3C 5

GENERAL CONSTRUCTION 12,477 136,450 136,450 136,450 243,581

HVAC 674,656 1,154,049 1,012,073 1,054,609 1,369,732

ELECTRICAL 40,412 56,203 56,203 56,203 168,391

SUBTOTAL 727,545$ 1,346,702$ 1,204,726$ 1,247,262$ 1,781,704$

GENERAL CONDITIONS - 15% 109,132 202,005 180,709 187,089 267,256

SUBTOTAL 836,677 1,548,707 1,385,435 1,434,351 2,048,960

G.C. OH & P - 21.0% 175,702 325,229 290,941 301,214 430,282

SUBTOTAL 1,012,379 1,873,936 1,676,376 1,735,565 2,479,241

DESIGN CONTINGENCY - 20.0% 202,476 374,787 335,275 347,113 495,848

SUBTOTAL 1,214,855 2,248,723 2,011,651 2,082,678 2,975,089

BONDS & INSURANCE - 5.0% 60,743 112,436 100,583 104,134 148,754

TOTAL CONSTRUCTION COST 1,275,597$ 2,361,159$ 2,112,234$ 2,186,812$ 3,123,844$

THE FOLLOWING ITEMS ARE NOT INCLUDED:

PROFESSIONAL FEES

CONSTRUCTION CONTINGENCY COSTS

FURNITURE, FURNISHINGS AND MOVABLE EQUIPMENT

INTERIOR FINISH REPAIRS, CUITTING, & PATCHING

FENCING AND PLANTINGS AT OUTDOOR UNITS

ENVELOPE IMPROVEMENTS: AWNINGS, WINDOW PANELS, PORCH DECK

INTAKE AND EXHAUST LOUVERS

ARCHAEOLOGY

NOTE: This chart is for reference only, and has been simplified from the Schematic Cost Study detail. Refer to Schematic Cost Study for further detail.

Page 1 of 1 8/11/2025 10:01 AM

Alternatives 2 and 3 will have a similar level of impact on the interior of Glenmont because the existing HVAC distribution system will remain the same. Alternative 5 will have the greatest impact due to an additional distribution system for the fan coil units which will require alterations to walls, ceilings, floors, and doors for new supply and return grilles.

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Alternatives 3A and 5 include trenching and placement of an outdoor unit remote from the house, which will be an impact on the cultural landscape. The trenching is expected to follow the line of the existing piping from the geothermal well field in an attempt to limit this impact.

Once a preferred alternative is selected, a more detailed estimate for the work such as a Class B estimate, can be completed.

APPENDIX A - FLOOR PLANS

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