Freeze Losses – Using a Thermal Analysis

Published January 10, 2018
By Stanley C. Stoll, M.Eng., P.E., CFEI, CVFI

Winter this year seemed to take its time getting here, but it looks like it is finally upon us. With winter comes insurance claims for freezing pipes that rupture and cause substantial damage to buildings. Take JFK International Airport in New York for example, who is mopping up after a water main broke due to a frozen pipe: read it here.

As you approach the freeze loss claims on your desk this year, we want you to consider some causes and what further evaluation might be available. We hear all the time, “the thermostat was set at 65.” But was it set at 65?

These are not easy questions to answer, but Knott has several ways to help out. There is always the initial look at the utility records and the comparison year over year to see if they indicate the fuel consumption dropped. This is a great indicator, but make sure you evaluate any other potential reasons for why the residence did not consume the same amount of fuel this month as it has consumed in past years.

When Knott approaches a claim like this, we take a scientific approach and evaluate the structure’s envelope as a whole and perform an energy analysis on the residence. In big picture, an energy analysis is evaluating the heat that is lost through the walls, floors and ceilings to the exterior compared to that which was delivered in the form of natural gas and/or electricity to heat the residence.

In more specifics, an energy analysis is performed by measuring the area of all walls, windows, floors and ceiling surfaces and assigning their respective thermal resistant values. The thermal resistant values are the insulation values known for each material and construction method. Once a thermal model of the residence has been constructed, weather records are evaluated to compare exterior and interior (or an assumed interior) temperature setting. This information is used to determine the amount of thermal energy that will be lost to the exterior. Once the energy loss is known, the amount of energy supplied to the residence, obtained by utility records and any photographs of the utility meters, can be compared to the energy that was lost to the exterior. If the energy lost does not match the energy input, it indicates one of the assumptions is inaccurate, like the reported thermostat setting, was not accurate and the thermostat was not actually set at 65. From there, the models can be adjusted to understand what the thermostat was actually set at prior to a frozen pipe.

Of course, there are items that must be accounted for, like was there an alternative fuel source such as a wood burning stove used in the residence. Or was there something inherently wrong with the structure that made a pipe susceptible to freezing, like a pipe being installed on the outside of the insulation – a construction defect. Don’t forget about the furnace malfunctioning. Once these items have been considered, the actual thermostat setting in the residence can be calculated.

Here are five items to document, if you think you might want to have a thermal analysis performed on a claim:

• When were the occupants last present in the residence?

• What was the thermostat set at after the loss – take a photograph.

• Document the readings on the gas and electrical meters.

• Document the type of heating appliances in the residence.

• And… don’t slip on the ice!