Building geometry in cove.tool is used for the following items:
- To calculate the Solar Gain, Heat Loss, and Wind-Heat Loss dependent on the height, orientation, and surface area of the thermal envelope.
- To select the inputs and standards which are dependent on the building size. For example, ASHRAE prescriptive inputs for building envelopes depend on the size of the project: a Small/ Medium/Large Office building each have their own set of R-values.
- To calculate the baseline inputs which are variables of available surface area (ex. CFM and Occupant Density).
- In the case of mixed-use projects, building geometry is used to split the building into specialized zones for differing building strategies. A mixed-use office/retail building will be designated by uploading geometry for the office area and retail area separately.
Cove.tool has two options for entering Geometry: Manual Mode and 3D Mode
- Manual Mode allows users to enter geometry information without a model. To see this process through, check out this article.
- 3D Mode is when users have a BIM model and use one of cove.tool's 3rd Party plugins, to export building geometry to cove.tool. This section will focus on setting up a model for 3D Mode.
- Both Modes require some amount of surface area in these 5 categories to allow the user to proceed: Building Height, Roofs, Floors, Windows, and Exterior Walls.
Making a 3D Model for cove.tool
cove.tool runs a single-zone energy simulation. The geometry needed to run this building analysis only requires inputs that represent the project's thermal envelope (required) and daylight obstruction (optional). Below, a diagram of a residential and commercial project in which their thermal envelope highlighted by a pink outline.
Note the thermal envelope should be a simple path between conditioned space and not-conditioned areas. (Examples of typical non-conditioned spaces include parking garages, open-air patios or walkways, mechanical rooms, un-insulated attics, so on).
Cove.tool has 8 geometry categories, 5 required, and 3 optional.
Required categories are minimum geometry required in order to access the daylight page. These are Building Height, Roofs, Floors, Windows, and Exterior Walls.
If your building design does not include one of these required categories, model a 1'x1' object to export in place of an empty view (example, a 100% Curtain wall building has no exterior walls but exporting a 1 SF panel is sufficient to meet the minimum requirement).
The optional categories are Skylights, Interior Walls, and Shading Devices.
Interior Walls and Shading Devices are primarily used for the Daylight related 3D simulations, and are not required but can help generate a bit more detailed results. Below is the same residential and commercial examples, but this time showing how they should be separated into the different categories for cove.tool's use.
For additional tips and clarification on how to determine which building components fall into what category, review the definitions below.
What is considered a roof, floor, window, ext./ int. wall, skylight, & shading device?
- Roof objects are defined as the insulated top surface of a conditioned space that protects against solar radiation and heat gain.
Roofs are part of the thermal envelope, therefore ceilings should not be considered roofs as they are not exposed to the outside environment. Roofs only depict the cap of a thermal envelope and may not expand beyond the conditioned space, such as a canopy, cantilever, overhang, balcony, etc.
- Floors are defined as a flat-horizontal surface area for regularly occupied and conditioned space.
Similar to roofs, floors do not expend beyond the conditioned space such as balconies, open-air walkways, terraces, etc. Also, floors area is the largest contributor to simulation wait-time, so be sure to remove any unnecessary individual objects such as stairs, windows sill, stages, or landings.
- Window objects can be classified by their low insulation properties in the vertical envelope.
Because they are a major factor in the envelope's bridging, transfusion, and infiltration attributes, it is important to only export windows on the building's envelope and not include any interior glazing objects. Also, windows are typically considered as a translucent and thin building material, however, this is not the case in energy simulation. The most important criteria for determining whether it belongs in the window layer or not, is 1) Is it in the building envelope layer, 2) are the insulation properties considerably lower than that of the exterior walls. Therefor objects like exterior doors and spandrels will also fall under the window layers export umbrella. These objects can also be exported in the shading device layer to provide shading when significant, however, the amount of daylight/radiation they obstruct will make nowhere near the impact on the building's EUI (Energy Use Intensity), then holes in the thermal envelope (which will affect heating/ cooling/ fans and more).
- Exterior Walls are defined as the highly insulated, up-right enclosing elements of a conditioned space that, like roofs, protect against solar radiation & heat gain, and subject to infiltration.
Exterior Walls should not continue inwards into the floor plan. Exterior Walls should also not include site walls or other outdoor shading obstructions; if it does not separate the outdoor and indoor environment, it is not an exterior wall.
- Skylights are considered holes of the tops surfaces of the thermal envelope and classified by their low insulation properties & direct exposure to solar radiation from above.
Skylights are a hybrid of roofs and windows objects, which enclose a below-conditioned space below but also are primarily used to bring in natural daylight.
- Interior Walls are defined as permanently installed up-right building elements that obstruct daylight from within the thermal envelope.
Interior walls object are not necessarily going to be used for the energy analysis model, but rather are crucial for modeling the conditions in the daylight simulation.
- Shading devices are defined as any daylight obstruction elements, not crucial to the insulation of the thermal envelope.
Objects like context, overhangs, fins, mullions, double facades, trees, stairs, furniture are examples of shading devices. Typically this export is the largest of any cove.tool project. When uploading shading devices to cove.tool, make sure the geometry is first simplified and not to include any high-mesh count objects like detailed tress, realistic rendering objects (furniture, fixtures, or manufacturer-provided elements). Learn more about what should be avoided in this article.
- Building Height is the vertical measurement of the lowest point to the highest point of conditioned space, and determine the buildings wind drag factor.
Learn more about building height here.
Once you have created a model in your respective BIM tool, upload your model using a 3rd party plugin. The plugins all include video tutorials and written guides on the unique requirements of each plugin workflow.