This article explains the 3 steps it takes to make your first project in cove.tool.
- What is the energy model? A brief recap of the science behind cove.tool
- Selecting Key Inputs: Building Location, Energy Code, and Building Type
- How to make a model for cove.tool?
Let's get started!
1. WHAT IS AN ENERGY MODEL?
An energy model is just the calculation of heat flow into and out of a building. It measures the amount of energy that must be expended in order to maintain the ideal level of indoor comfort, thus the name Heat Balance Equation Method.
Since the "primitive hut", humans have always sought ways to improve their shelters and make even the most hostile environment comfortable. Whether their building strategies were designed to combat hot/cold/wet/dry/or mild climates, or locations with poor air quality, high winds, seismic events, and/or resource scarcity, humans have found solutions to build ever-evolving shelters. Today, building science continues this tradition with the development of rules and equations to combat these classic struggles as well as address the demands of the modern world (ie. human rights, growing populations, technologies, hyper-specialized building typologies, and, most importantly, climate change).
There are four key ingredients to an energy simulation:
- Recreating the conditions of your environment; using weather files, a typical climate season is simulated which includes everything from humidity, temperature, radiation, precipitation, evapotranspiration, wind, and more.
- A model representation of your building: every geometric configuration will result in a unique set of conditions and can help determine which strategies must be pursued in order to optimize the building's performance.
- The performance and mechanical strategies of building systems and products; the better compatible each of the strategies become with the environment and the building design, the more efficient the design becomes.
- The last ingredient is energy codes, building standards, and simulation methodologies; the standards and equations which are used to ensure outcomes of your building meet the minimum safety and zoning requirements, as well as accurately measuring the performance of your building design are key towards understanding what your baseline looks like and setting up targets to achieve.
2. Selecting Key Inputs
I. Selecting a Building Type
Building Type is a template used to differentiate the components of your building into their proposed energy & programmatic categories.
When selecting a building template, the user is linking their project with a set of standardized energy consumption & expenditure data, component efficiencies, and control strategies unique to their commercial or residential building type (i.e. the PNNL Prototype Buildings). Templates are there to help initiate the project's inputs and jump-start the automation process. More information on how building templates are generated here. Building templates are also used to help find the best fit for prescriptive inputs when the decision is based on the program and selecting relevant building products for cost optimization.
When you start a new project, you will see the 8 building templates. According to the American Institute of Architects (AIA), the standard 8 types will cover 80% of all projects which are just a collection of engineering inputs and factors. However, for projects outside of these 8 standard types, users can further customize an existing template to model a unique use-type project. This article lists the other 60+ building types which cove.tool supports, and this article is a guide on creating custom templates for your project (ex. modeling a K-12 school, religious center, gym, and more).
Projects with single use-type (1 template selected) will have only one building type through the project, but mixed-use projects inside cove.tool (multiple templates) can have up to 3 parallel building templates in a single cove.tool project. When creating a mixed-use project, the key is knowing where the building splits to a new function that demands different inputs for the spaces. Review the reasons you might want to create a mixed-use project, in these situations below:
- There are different mechanical strategies for different spaces in the building. For example, a hospital building with office spaces may need two system types that support the unique demands of either space.
- There are different envelope properties for each space. For example, a project with below-grade functions will have envelope properties drastically different from the above-grade space. This situation occurs in most urban commercial spaces where store-front glazing is the first level and the rest of the project is an air-tight wall assembly. The two spaces need specific inputs for each space.
- There are different schedules for each space. For example, a sports arena will have office spaces that are occupied daily, however, their largest energy expenditure, the stadium, and support spaces are only used a couple of days out of the year. Since these spaces will both contribute to the EUI but have wildly different expenditures dependent on the calendar then it is important to split these spaces to demonstrate their operations schedule.
Further clarification on which template to select can always be clarified by a Live Chat support expert.
II. Selecting a Building Location
When starting a new project, users will be required to add a building's location in the form of a street address or as geo-coordinates (examples below). This input will select the nearest and most recent weather file, align the project with regional manufacturing costs and utility rates, carbon benchmarking using the Architecture 2030 methodology, and also site your building in its real-world context. Not much decision making is required here, just have where your building will be located is need to create the environment for your energy model.
Once the geometry has been loaded into the Daylight Page, if the placement in the site is incorrect, use this video tutorial to edit the scene.
III. Selecting an Energy Code
Energy Codes set minimum efficiency requirements for new and renovated buildings, assuring reductions in energy use and emissions over the life of the building. Code buildings are more comfortable and cost-effective to operate, assuring energy, economic and environmental benefits.
In cove.tool, the project's energy code is automatically selected based on building location. The selected code will load all the prescriptive inputs (envelope, lighting, etc.) based on the codes. Other inputs that are not specified by energy codes are based on industry-standard practice, ASHRAE User's Manual, and the PNNL Prototypes.
Available energy code options are listed in the Energy Code section in the Help Glossary article. Options include national (domestic and international), state/province, and local/city amendments energy codes and standards. If interested, PNNL has a great article on understanding building energy codes and standards here, which breaks down the extent and demand for performance targets and regulations. We are adding more all the time. If your country or code is not yet in cove.tool please let the support team know and any resources or links to the requested code version.
2. BUILDING GEOMETRY
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.
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.
When preparing to upload the building geometry for cove.tool it is crucial to filter each element into the correct geometry category. Cove.tool has 8 geometry categories, 5 required, and 3 optional. The 5 required categories are minimum geometry required in order to access the daylight page. These 5 are Building Height, Roofs, Floors, Windows, and Exterior Walls. If your building design does not include one of these required categories it is sufficient to model a 1'x1' object and export for that category (example, a 100% Curtain wall building has no exterior walls but exporting a 1 SF panel is sufficient to meet the minimum requirement).
The 3 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 unless they are not exposed to the outside environment. The roof object for cove.tool must only depict the cap of a thermal envelope and not expand beyond the conditioned space such as a canopy, cantilever, overhang, balcony, etc. Make these objects shading devices instead.
- Floors are best defined as a surface area that bounds a conditioned space from below, and the best indicated for regularly occupied and conditioned space. Similar to roofs, floors do not extend beyond the conditioned space such as balconies, open-air walkways, terraces, etc.
- Window objects can be classified by their low insulation properties, and are mostly attributed as holes in the project's thermal 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. Therefore 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 and heat gain. Exterior Walls should not continue inwards into the floor plan, those objects would be interior walls and only provide daylight benefits rather than exterior walls which impact the building's energy use. 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. Last, in the case of a mixed-use project or limited interior study, exterior walls may not have to be included for energy analysis. In a mixed-use project study, where two programs are side-by-side, split by a wall in between them, this wall would technically be the edge of a thermal envelope for both uses, but since it is not exposed to the outdoor environment, it will not generate heat loss/gain/etc and would be defined as adiabatic wall and is better fitting for the interior walls category. In the case of a limited interior study, such as a renovation project of 50% of the 4th floor in an existing hospital, users only need to export exterior walls that are relevant to the envelope of their analysis area. It would not be necessary to export the entire building or floor if you are only looking at a single space. Further direction can be provided in a discussion with the Live Chat support team.
- 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. The amount of daylight obstruction your interior walls provide will impact the sDA%/ASE% of your project, which may in turn impact your energy results if sensors are included in the building design. Underground spaces that are occupied, like basements, should export all walls into this category to maintain the accuracy of the energy model. Floors for these areas should be uploaded on the floor layer.
- 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, under the Highly triangulated surfaces section.
- Building Height is the vertical measurement of the lowest point to the highest point of conditioned space and determines the building's 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.