Increasing Resiliency in Cold, Arctic Climates
In mission-critical facilities in extremely cold climates, how long do engineers, system designers and facility managers have to correct energy supply problems before indoor air temperature drops below habitability or sustainability thresholds?
A study conducted by a research team with the U.S. Army Corps of Engineers Research and Development Center (ERDC) recently addressed this question, and the results are included in ASHRAE’s Guide for Resilient Thermal Energy Systems Design in Cold and Arctic Climates.
The first-of-its-kind attempt was designed to address a deficiency in the industry’s ability to monitor and model thermal decay in cold environments, according to Alexander Zhivov, Ph.D., Fellow/Life Member ASHRAE, a research/development engineer at the Construction Engineering Research Laboratory for the ERDC. The thermal decay test (TDT) was designed to help the industry better understand the level of reliability required for energy supply systems that can support environmental conditions required for a facility’s mission, occupant comfort and sustainment of a building in arctic environments under predominant threats. On top of testing the reliability of the thermal systems in real-time under actual extreme conditions and high winds (summer and winter air leakage tests), the research also built a model to better forecast future cases and vulnerable failure mechanisms, Zhivov said.
“Information provided in the guide allows prediction of temperature decay in buildings when thermal energy supply to the building is lost without putting a critical facility at risk,” said Zhivov. “This allows buildings to have a maximum time to repair (MTTR) determined so that emergency and facility managers can prioritize resources in times of need.”
Addressing the Arctic’s Challenges
The Guide for Resilient Thermal Energy Systems Design in Cold and Arctic Climates describes best practice examples of robust and reliable HVAC, plumbing and thermal energy systems with the emphasis on their redundancy, durability and functionality. It also discusses the most common heating system and ventilation system approaches used in arctic climates.
“The information provided in this guide was not previously available. One of the most visible consequences of a warming world is an increase in the intensity and frequency of extreme weather events, especially in extreme climates,” said Zhivov.
Foundation options on permafrost vary widely and are dependent on intended use, allowable risk, budget, location (climate and permafrost characteristics) and logistical constraints, said Zhivov.
“Shallow ice-rich layers can be excavated and removed, whereas deeper lying ground ice may require the structure to be elevated on piles or columns/pads to allow for winter air to flow under the structure,” he said. “Alternatively, mechanical freezing may be prescribed using buried refrigeration loops either with mechanical cooling or thermosyphons.”
Designed for energy systems designers, architects, energy managers and building operators involved in building planning and operation in cold and arctic climates, the guide focuses on resilience of thermal energy systems and emphasizes the importance of a maintenance program that allows building operators to successfully troubleshoot and maintain buildings in the arctic.
“The main challenges for construction and maintenance of these systems include extremely cold outdoor air temperatures in winter and high temperatures in summer and remote locations. Special attention shall be paid to construction in areas with frozen soil,” Zhivov said.
This guide is meant to complement the ASHRAE Cold-Climate Buildings Design Guide, Second Edition.