ASHRAE’s space conditioning types include: conditioned space, unconditioned or semi-heated space. ASHRAE’s definitions for these types:

**space**: an enclosed space within a building. The classifications of spaces are as follows for the purpose of determining building envelope requirements.

(a) conditioned space: a cooled space, heated space, or indirectly conditioned space defined as follows.

1. cooled space: an enclosed space within a building that is cooled by a cooling system whose sensible output capacity exceeds 5 Btu/h*ft^{2} of floor area.

2. heated space: an enclosed space within a building that is heated by a heating system whose output capacity relative to the floor area is greater than or equal to the criteria in Table 3.1.

3. indirectly conditioned space: an enclosed space within a building that is not a heated space or a cooled space, which is heated or cooled indirectly by being connected to adjacent space(s) provided:

(a) the product of the U-factor(s) and surface area(s) of the space adjacent to connected space(s) exceeds the combined sum of the product of the U-factor(s) and surface area(s) of the space adjoining the outdoors, unconditioned spaces, and to or from semi-heated spaces (e.g., corridors)

**or**

(b) that air from heated or cooled spaces is intentionally transferred (naturally or mechanically) into the space at a rate exceeding 3 air changes per hour (ACH) (e.g., atria).

(b) semiheated space: an enclosed space within a building that is heated by a heating system whose output capacity is greater than or equal to 3.4 Btu/h*ft^{2} of floor area but is not a conditioned space.

(c) unconditioned space: an enclosed space within a building that is not a conditioned space or a semiheated space.