The “Little White House” was built by Franklin Delano Roosevelt in 1932 in Warm Springs, Ga., a small town in which Roosevelt often retreated for rest and physical therapy for the paralysis caused by the polio.The trustees of the Georgia Warm Springs Foundation, to which FDR willed the Little White House, donated the property to the State of Georgia on the condition that the Little White House was suitably administered as a memorial. The State of Georgia established the Franklin D. Roosevelt Warm Springs Memorial Commission in January 1946. In July 1980, administration of the memorial was transferred to the Parks, Recreation and Historic Sites Division of the Georgia Department of Natural Resources.
Today, buildings on the property include the original, unrenovated Little White House and servants’ quarters; a 10,500-square-foot (976-m2) museum, which was built in April 2004; and 3,305-square-foot (307-m2) existing gatehouse that was converted into an entrance for the museum. The existing maintenance barn was deconstructed and replaced with a new maintenance barn. The water system for the property was upgraded, and the existing administrative offices received interior renovations. The museum and renovated gatehouse were certified Silver under LEED for New Construction, a green-building rating system of the Washington, D.C.-based U.S. Green Building Council. The project was accomplished through a design-build delivery method within a $5 million budget. rest and physical therapy for the paralysis caused by polio. After his death in 1945, thousands of visitors sought to visit President Roosevelt’s Little White House.
MOISTURE: A MUSEUM’S ENEMY
Museums have very special requirements for maintaining indoor temperature and humidity conditions to maintain historic artifacts. The Georgia Department of Natural Resources selected Buford, Ga.-based Commissioning & Green Building Solutions Inc., or CxGBS, to identify and help correct issues that would have affected the Little White House Museum’s intent and performance, including moisture control, correct operation of demand-based ventilation, accessibility to equipment for routine maintenance, incomplete work and missing equipment required for operation of the facility.
The new museum and renovated gatehouse are conditioned by a watersidechiller that uses a cooling tower supplied by a roof storm-water collection system and supplemented by the updated water system when necessary.
Two variable-air-volume air handlers with electric reheat and return-air humidifiers maintain interior temperatures between 68 and 78 F (20 and 26 C) and relative humidity between 45 and 55 percent. One of the main constraints in temperature and humidity control in a museum occurs in the winter when indoor humidity levels could typically drop to 20 to 30 percent relative humidity without humidification. Raising the indoor relative humidity to the desired 50 percent requires significant energy and limits setback temperatures during unoccupied periods. The table on page 37 illustrates the difficulties associated with lowering space temperature.
As shown in the graph, lowering the room temperature from 72 F (22 C) at 50 percent relative humidity to 65 F (18 C) as a conservation measure raises relative humidity levels to 75 percent, causing excess moisture levels in the building and potential for mold growth. Mold growth occurs when all of the following conditions are present:
• Temperatures between 45 and 95 F (7 and 35 C)
• Organic nutrients from building materials
• Moisture (water or relative humidity above 70 percent)
A Leed silver museum two years after completion.
It is essential to understand this phenomenon when operating the museum because the higher humidity levels will damage artifacts unless the building is dehumidified.
During the commissioning process, after the controls contractor had completed his programming, CxGBS observed humidity problems while conducting system-performance testing and observed condensation forming in the artifact storage area. Working with the building operator, the controls contractor and designers, changes in sequences of operation and establishment of operating parameters were implemented to protect the artifacts within FDR’s Little White House Museum. Understanding how wall and HVAC systems work was critical to correctly operating the facility after commissioning.
For example, CxGBS discovered designers and contractors often misunderstand how demand-based ventilation control should be designed and installed. Designers who do not specify a clear sequence of operation leave how to set damper positions and implement control
sequences open to contractor interpretation. In the Little White House Museum, the control contractor called for the outside air damper to modulate between open and closed based on carbon-dioxide concentrations in the building’s interior. This would have caused the building to fluctuate between positive and negative pressurization and introduced too much outside air during periods of high visitor occupancy. The commissioning process identified the correct minimum outside-air damper position during occupied periods to maintain positive pressurization and maximum outside-air damper position to meet ventilation requirements specified by the designer. These damper positions do not exceed the HVAC system’s capacity to properly condition the outside air.
FDR’s Little White House Museum was designed to reduce operating energy costs by 36.89 percent compared with a building constructed to ASHRAE Standard 90.1-1999. Some of the energy efficiency features include the following:
• R-20 continuous insulation on the roof and R-19 continuous insulation on the exterior wall with 6-inch (152-mm) metal studs for the new building addition
• 1/2-inch (13-mm), low-E, double-pane insulated windows
• 45 percent reduction in general lighting power density
• Dimmable display lighting
An energy analysis for the Little White House Museum was performed using eQuest and calculation protocol from USGBC’s LEED version 2.1, which is derived from ASHRAE 90.1-1999. Chapter 11, “Energy Cost Budget Method.” The original model completed in 2003 predicted that the regulated load, which includes heating and cooling, general lighting and service hot-water heating, would be 14.43 kilowatt hours per square foot per year. The unregulated loads, which include exhibits, exhibit lighting, rainwater make-up pump, plug loads, operation of exhibits, theater, etc., were estimated to be 17.05 kWh/square foot/year resulting in predicted energy usage for the museum and renovated guard house to be 31.48 kWh/square foot/year.
CxGBS discovered designers and contractors often misunderstand how demand-based ventilation control should be designed and installed. Designers who do not specify a clear sequence of operation leave how to set damper positions and implement control sequences open to contractor interpretation.
ASHRAE 90.1-1999 does include process loads, such as the exhibits, exhibit lighting, theater operation, etc., within the regulated energy-costbudget calculations. Table 2, page 38, shows the original lighting-power-density assumptions for the Little White House Museum. It is easy to see that moving the exhibit lighting alone into the unregulated column significantly reduces the regulated lighting load and is a major contributor to the building’s calculated energy efficiency.
Based on 2005 actual energy usage the facility consumed 42.46 kWh/square foot/year, which is approximately 25 percent more than the original energy model predicted. To correlate between actual energy usage and calculated energy usage predicted in the original energy model CxGBS must obtain actual weather data for the area during the same period. This weather information has several problems because the museum is 40 miles (64 km) north of the closest weather station and hourly information was missing. In addition, the following conditions are unknown:
• Actual weather conditions versus historic averaged annual data used by energy-modeling software
• Variations between actual conditions and ones assumed by the energy modeler
• Additional equipment installed not included in the original contract documents
• Changes by building operators
The actual energy consumption of a well- commissioned building is the best benchmark for establishing energy performance. The commissioning process verifies that building systems are operating as intended. Fluctuations in energy consumption need to be identified and analyzed so that operators and owners can maintain a building at peak performance for its lifespan.
With actual energy usage 25 percent greater than predicted in the Little White House Museum, efforts are currently underway to analyze and understand why the predicted performance is not closer to actual. For example, CxGBS is recording actual electrical consumption for lighting, plug loads and equipment loads that can be compared to initial assumptions, so the energy model can be revised to reflect what actual conditions are.
CxGBS also is trying to correlate the years of electrical bills to the actual weather that occurred during those years so the team can compare at the performance of the energy model to the actual performance of the building using the same assumptions and parameters. By completing this analysis, the Little White House Museum and its
artifacts will continue educating many generations about one of our nation’s most revered presidents.
>> H. JAY ENCK is founder and chief executive officer of Commissioning & Green Building Solutions Inc., Buford, Ga. He can be reached at email@example.com or (770) 831-6760.