Fire poses one of the greatest risks to historic places, but its prevention and extinguishment can also present a high risk to historic materials. Installing a traditional sprinkler system can negatively impact the character of a historic place, and the high volume of water used to quell fires can oversaturate fragile features. In the 1990s, a new solution was developed in Finland to mitigate the risk of fire, reduce subsequent water damage, and prevent major disruptions from installation: HI-FOG mist fire suppression systems. This innovative technology has protected historic places worldwide, including a historic cathedral in the remote community of Unalaska on the Aleutian Islands of Alaska.

Designated as a National Historic Landmark in 1971, Holy Ascension of Our Lord Cathedral is one of the oldest Russian Orthodox churches in Alaska. The cathedral’s history dates to the 1750s when Russian Orthodox missionaries started preaching to European fur traders and Alaska Natives. The current cruciform cathedral was built in 1896, replacing earlier churches on the site. Few modifications have been made to the cathedral despite ongoing use by the congregation, community, and visitors.

Holy Ascension has faced a heightened risk of fire throughout its history. The wooden cathedral hosts worship services that involve lighting many candles. Housed within the cathedral is a priceless collection of historic church icons and artifacts, transported to the Aleutian Islands over rivers, mountain ranges, and the ocean in treacherous conditions. Fire could destroy the church and its collection in the approximately five minutes it would take firefighters to respond.

Since 2013, the congregation, in partnership with Russian Orthodox Sacred Sites in Alaska (ROSSIA), a nonprofit focused on preserving Alaskan churches and religious iconography, has discussed upgrading fire protection at Holy Ascension. Congregants and stakeholders worried that Holy Ascension could burn down like other churches in Alaska, including St. Michael’s Cathedral in Sitka.

HI-FOG Mist as Fire Prevention

While Holy Ascension installed its first fire alarm system during a 1996 restoration and replaced these alarms around 2015, the cathedral never invested in any type of fire suppression system. ROSSIA proposed installation of a HI-FOG mist fire suppression system, which worked well at another National Historic Landmark, Holy Assumption Church in Kenai, Alaska.

As fire protection expert Jack Watts explained in the National Trust for Historic Preservation’s publication Fire Safety in Historic Buildings, HI-FOG mist fire suppression systems have many advantages for historic places compared to traditional sprinkler systems. By using high pressure water to penetrate the seat of the fire, cool the air, block heat, and starve the fire from oxygen, this system uses much less water, avoiding potential damage to fragile historic materials and collections. Additionally, the system can function even during harsh weather conditions or power outages because it relies upon pumps operated by compressed nitrogen as opposed to utility electric service.

A Closer Look At Installation

The HI-FOG mist fire suppression system installed at Holy Ascension was tailored to the size and needs of the space. Twenty-five gas pump units (GPUs) powered via compressed air or nitrogen and stored in pressurized containers are connected to the cathedral via a stainless-steel, insulated piping system in an underground utility tunnel. Water is then transported to 75 mist sprinklers installed in the ceiling of the cathedral’s occupiable areas. Considering Alaska’s climate, contractors used a dry system at Holy Ascension. Pipes are only filled with water when a fire alarm is triggered, and a releasing control panel is activated. The dry system causes a slight lag in water reaching the mist sprinklers but prevents the pipes from freezing.

Despite delays resulting from the COVID-19 pandemic, ROSSIA and Holy Ascension completed the installation of the fire suppression system in late 2021. David Gregory, a ROSSIA board member who was highly involved in this project, spoke to the impact of the project: "The installation of the fire mist system has been a wonderful addition. The Parish has always lived in fear that a fire would destroy our beloved cathedral. Now we can rest easier knowing we have one of the best fire systems for protecting our historic church." ROSSIA also looks forward to opening up Holy Ascension to tours now that cruise ships are starting to operate again.