Air Floors

How to use Air floors to model double height and mezzanine spaces

Written by Christopher Riddell
Updated over a week ago

## What is an Air Floor?

An Air Floor is a type of floor element that can be used to divide spaces between levels of a building without a physical floor slab. Similar to Air Walls horizontally, an Air Floors allows separation of rooms vertically within a building. They can also be used to represent the vertical space that runs through a building and accommodates vertical transportation, mechanical systems such as ducts, pipes, and electrical conduits. Such shaft spaces are not typically heated, cooled, or ventilated The following are examples of where you would model an Air Floor :

1. Atrium: An air floor may be used to represent the space above the base level of an atrium. For example an atrium that extends four stories would be represented by one room with a floor on the base level, and three rooms on each next level with an air floor.

2. Stairwell: An air floor may be used to represent the stacked rooms that make up a stairwell in a building.

3. Double-Height: Rooms that have higher floor to floor height than their neighbors are considered double-height. Common examples include gymnasiums, auditoriums, and lobbies. These can be modeled as two rooms, with the top room having an air floor.

## How to draw Air Floors?

Air Floors are not drawn directly with the interface, instead we convert Floors into Air Floors via the toggle in the Properties Panel. To create an Air Floor, first start by drawing the rooms of your project, remember that Floors will automatically be created! Next follow these steps:

1. Select the interior floors that will be converted to Air Floors.

2. Once selected, locate the Floor sidebar properties on the left and Select the "Air Floor" checkbox to convert the Floor to an Air Floor.

Important Notes:

1. Air Floors need to be present within the thermal envelope of the building and therefore will always be surrounded by walls.

2. Air Floors have limited properties that can be assigned.

3. Air Floors should not be placed on the ground floor or over hanging floors.

## How does an Air Floor impact analysis?

#### 3D Analysis:

Air Floors are exported as voids in the floor plate in 3D Analysis. This means that daylight and views will pass through them. Since Air Floors are voids make sure to uncheck the "Occupied" field in the room properties when exporting which excludes these rooms. from the required "Regularly occupied spaces" needed when creating the Occupied vs Unoccupied LEED Report.

#### Baseline Energy Page:

Air Floors will also impact the Baseline Energy model by reducing the total floor area, each floor assigned as an Air Floor will be deducted from the total. This will impact energy consumption for end uses such as lights and equipment which are calculated based on the total building area.

For calculations in EnergyPlus, the Air Floors do not include any conduction gain components and do not block solar gain. This means that elements like skylights can show solar gain for rooms below an Air Floor. In addition rooms with an Air Floor will have an area of zero in the simulation, so any internal loads such as occupants or equipment calculated per area will also be zero. To include loads in these rooms define them with an absolute input.

Note - for information the area is noted in the Project Editor and Results for rooms with Air Floors. However, as noted above the area is not part of the simulation.

## Air Floor Properties

Air Floors only have reporting properties, such as area. This is of course due to their representation of lack of material.