February 1, 2023

A New Geothermal System Provides a Heart Transplant to Brucemore

In 2022, Brucemore, a National Trust Historic Site in Cedar Rapids, Iowa, completed the installation of a geothermal HVAC system. The installation in an 1886 Queen Anne mansion that anchors a 26-acre landscape was carefully executed to bypass the home’s original steam heat infrastructure. Grounded in the philosophy that a commitment to historic preservation is a perpetual responsibility, the project repeatedly adhered to the credo that short-term fixes are ultimately more expensive and less effective.

View of a digger at the National Trust Historic Site Brucemore as it prepares to install Geothermal systems.

photo by: Brucemore

Installing a geothermal HVAC system at Brucemore required directional boring and trenching to upgrade the mansion’s electrical power supply.| Credit: Brucemore

Heating Brucemore: A Historical Perspective

Caroline Sinclair, the widow of a Midwest meatpacking scion, oversaw the completion of the mansion’s construction in 1886. Designed as a home to raise her six children, the structure featured 18 modestly sized rooms. During the harsh Iowa winters where temperatures could drop below zero, coal boilers fueled by a then state-of-the-art steam heat system were supplemented by 14 fireplaces on five chimneys to provide warmth and protection.

During the sweltering heat of the summer, relief was provided by scores of windows and the siting of the home atop a gentle, windswept hill. Over several decades, undersized air-conditioning units were added to cool a few key living spaces, but the upper floors continued to suffer from heat over 90 degrees and high relative humidity. Eventually, the boilers were converted to gas, but the system spread inconsistent heat to the individual spaces, simultaneously desiccating the air each winter.

As the aging estate transitioned from a private residence to a national model for historic sites—the site was bequeathed to the National Trust in 1981 and is operated by Brucemore, Inc—the preservation challenges mounted. The dependence on the antiquated environmental control system made the interiors uncomfortable for people, and destructive for artifacts and interior finishes. Efforts to repair and replace the steam boilers several times in recent decades came at a great expense, and the ability to employ staff with the expertise and time to coddle the fragile system became increasingly difficult.

Trenching occurred on the six-acre lawn in front of the mansion to install a geothermal wellfield. | Credit: Brucemore

More ominously, the visible and increasing failures in several exposed pipes suggested the 130-year-old piping system concealed in the walls was not faring much better, but was hidden from view. The possibility, and occasional occurrence, of a boiler failure in the winter posed a great threat to public programming and a looming structural, preservation, and financial crisis.

Updating the infrastructure of the Victorian-era residence was both necessary and daunting. Brucemore leadership commissioned a holistic HVAC study through an architecture and engineering firm in 2020 to evaluate a range of options.

  1. An air-cooled variable refrigerant flow system.
  2. A water-cooled variable refrigerant flow system.
  3. A water-cooled air-to-air heat pump system.
  4. Steam heating with air cooled split system air conditioning.
  5. Steam radiators with gas furnace systems.

After careful consideration, a water-cooled variable refrigerant flow system that utilizes a geothermal energy source was selected. With an eye towards future maintenance costs, this solution offered long-term sustainability, energy efficiency, environmental control of individual spaces, improved ventilation, and humidification of key spaces. It also did not require equipment to be visible on the exterior, minimized disruption to the historic interiors, and offered low sound levels.

The Technology Behind Cooling and Heating Brucemore Today

Today, a visitor walking across the six-acre “front” lawn may not realize the technology deep beneath their feet. A geothermal wellfield serves as the heat source and sink for the robust system hidden within the mansion. Each loop consists of many segments of directionally bored pipe at a depth of 15 or 30 feet below grade. This depth allows the system to harness the Earth’s steady temperature to bring the glycol and water mixture back to 55 degrees Fahrenheit, limiting the energy required to heat the mansion in the winter. In the summer months, the wellfield works to shed the heat from the structure. Within the mansion, the design allows variable heating or cooling amongst multiple zones, providing customization for a variety of interior spaces with different orientations and large windows.

Energy recovery units located in the attic and basement circulate outside air into the mansion, improving air ventilation and maintaining the desired temperature. To account for the increased ventilation, humidifiers help offset the dry winter months with emphasis in key spaces. Strategically located sensors allow for monitoring and data collection necessary to continue to customize the system and address issues..

The building’s structure required upgrades to the backbone infrastructure to support this project, including electrical power, and fiber communications.

A basement room used for storage was converted into a geothermal mechanical room. The glycol-water mixture circulates from the wellfield into this space using two pumps. | Credit: Brucemore

Creative Solutions for HVAC in a Historic House

Installing the new HVAC equipment and routing the refrigerant and electrical lines within the 19th century mansion required a project team with an appreciation for the nuances presented by a large, quirky historic home. Reviewing and adapting design plans throughout the project to address the implementation challenges resulted in a thoughtful and creative solution that minimized the loss of historic material and ensured reversibility.

Closets and storage spaces—above or below the zone—hide the fan coil units that heat or cool the space; however, the design considered interpretative opportunities. In a bedroom on the servants’ side of the home, a fan coil unit was intentionally left on display next to a historic radiator to provide contrast between the original steam system and modern geothermal technologies.

Staff worked closely with the architects, designers, and contractors to determine the best solutions for routing necessary mechanical piping and electrical conduit throughout the mansion while minimizing the impact on the historic fabric. | Credit: Brucemore

With most large equipment housed in the basement or attic, channels were created between the levels to allow the refrigerant, controls communication, and power to connect on each level. An existing freight elevator was decommissioned to create a chase to connect each floor. The elevator car was stationed at the basement level where it can be displayed. Decisions to make necessary penetrations to install ductwork, pipes, and grills throughout the home was unnerving, but in the end, minimized distractions.

A sleeping porch designed in the 1920s by internationally known artist, Grant Wood, presented a significant challenge to the design of the system that will also be one of the most rewarding for long term preservation of a rare artifact. The plaster on brick wall finish is very susceptible to temperature and humidity changes; however, altering the walls to mount a grille was not allowable. Instead, a system large enough to push air through the porch by way of the adjacent room was designed and installed in a nearby closet. This system is able to maintain a tight design range of temperature and humidity, ensuring the plaster will not need to expand and contract as much as it has in the past.

In other spaces, such as the pipe chamber for the rare 1920s Skinner residential organ, decisions were made to balance control of the space without introducing new airflow or particulates. The room will be passively heated and cooled from its anteroom to avoid disrupting the sound produced by the organ.

Closets in several interpreted rooms were utilized to hide the mechanical equipment added as part of the geothermal project to heat and cool the mansion. This minimized the visual disturbance and interpretation to spaces like the nursery. | Credit: Brucemore

Upgrading the heating and cooling system of the 1880s mansion represents a fundamental investment in long-term preservation. It addresses systemic causes that pose a threat to not only the structure, but the artifacts housed inside, and does so in an environmentally conscious way. The most commonly cited measure for evaluating a major change in utilities is how quickly the lower energy costs will compensate for the investment in new technology.

While Brucemore’s mansion no longer requires any natural gas service, a cost increase in electricity is projected and will be tracked. However, in the final analysis the cost/benefit of the project will not be found in annual utility bills. Rather, abandoning the dangerously antiqued building system and investing in a modern heating and cooling systems is a fundamental step in ensuring the relevance and preservation of the structure for the next century.

David Janssen is the executive director of Brucemore, a National Trust Historic Site.

By: David Janssen

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