IECC Q&A: Warehouse freeze protection

In this column, we will address some of the typical questions asked of our technical support team. As always, code opinions issued by International Code Council staff are based on published Code Council codes and do not include local, state or federal codes; policies; or amendments. This opinion does not imply approval of an equivalency, specific product, specific design or specific installation and cannot be published in any form implying such approval by the International Code Council. As this opinion is only advisory, the final decision is the responsibility of the designated authority charged with the administration and enforcement of this code. All code citations reference the 2018 International Energy Conservation Code (IECC) unless otherwise specified.

Warehouse freeze protection

Q: Can a storage warehouse be built without wall and roof insulation if the space is to be maintained above 32 degrees Fahrenheit only to keep water pipes from freezing during cold winter days?

A: Unlikely, but it depends on your climate and equipment needed to maintain temperatures above freezing. Both the IECC and ASHRAE 90.1 reference “low-energy” buildings. Section C402.1.1 exempts low-energy buildings from the thermal envelope requirements of the code, including those buildings without conditioned spaces and those with a peak design rate of energy usage less than 3.4 Btu/hr*ft2 of floor are for conditioning purposes.

These buildings are only exempted from the envelope provisions and must still be in compliance with the heating, ventilation and air conditioning; service water heating; electrical; and lighting systems provisions found in the balance of Chapter 4 [CE].

The phraseology “a peak design rate of energy usage for space conditioning purposes” refers to the total peak primary energy used for space conditioning. There is no distinction in the code regarding where the energy is derived from, just a limit on usage. The usage is for space heating or cooling. There are no limits placed in such buildings for the energy used for lighting or service water heating other than those found in the balance of the chapter.

Few buildings designed for human occupancy will qualify for this exemption. If an exemption is claimed for a building, the permittee should provide enough supporting documentation to validate the claim. The peak rating of an appliance or piece of equipment can be determined by its nameplate rating or the manufacturer’s literature.

Portions of buildings can also qualify for this exemption. Where a portion of a building meets the criteria for this exemption, that portion of the building is not required to comply with the envelope requirements. Other portions of the building, including the construction assemblies separating conditioned and unconditioned portions, define the limits of the building envelope that must meet the code requirements.

Additionally, ASHRAE 90.1 Tables 5.5-0 through 5.5-8 provide thermal envelope requirements for semi-conditioned spaces, which use more energy for conditioning than a “low-energy building” and less than a “heated building”.

Finally, note that in accordance with Section C401.2 of the 2018 IECC, ASHRAE 90.1 may be used as a compliance path. If so chosen, it must be the compliance path for the entire project.