New Honeybee-PH Tool Improves Workflows for Modelers

Having worked on huge numbers of Passive House projects over the years, we at bldgtyp are more convinced than ever that Passive House is a really useful framework for designers, builders, and building owners. However, we have also experienced first-hand how difficult, time-consuming, confusing, and frustrating the modeling and certification process can be for the design professionals involved. We believe that if we can help smooth out some of the headaches and roadblocks in the design and engineering process, more folks will take advantage of the Passive House approach to build better buildings.

With that goal in mind, we have released a series of free software tools designed to make Passive House energy modeling faster, easier, and more fun at passivehousetools.com. The newest member of this toolkit is the Honeybee-PH plugin for Ladybug Tools and Honeybee. Honeybee-PH helps streamline data management and modeling—particularly critical when working on large and complex Passive House buildings—allowing users to more quickly send data from a 3D building information model (BIM) to PHPP. By utilizing this new tool, Passive House modelers can easily output dynamic energy models, daylighting and thermal comfort assessments, and a complete PHPP—all from the same 3D BIM—while simultaneously producing a clear documentation trail for the certifier. And, while this article focuses on the PHPP process to explain the utility of Honeybee-PH, the tool can be equally helpful in exporting BIM data to WUFI-Passive.

Non-Residential Workflow Challenges

Modeling non-residential buildings brings a unique set of challenges not found at the small residential scale. These large buildings may have complex geometries, complicated construction assemblies, multiple thermal-zones, and multiple programs, or use-types, each with their own utilization-schedules and loads. In addition, values such as lighting installed-power-density, utilization-rates, occupancy schedules, and electrical equipment loads have very large impacts on these buildings’ primary energy demand—in some cases exceeding the impact of the heating and cooling loads.

It is, therefore, critically important for modelers to have easy access to robust and flexible data for internal loads and schedules, as well as tools to effectively manage the inherent complexity of buildings with many different use-types. While the PHPP does a good job at incorporating these loads into the final energy use results, the lack of a strong BIM connection inhibits the ability of modelers to input, update, and validate this information accurately and easily at the space-by-space level.

Honeybee-PH Workflows

The free, open-source Honeybee-PH toolkit has been developed to help modelers overcome the challenges of large and complex building modeling by essentially smoothing the flow between the popular 3D modeling program, Rhino3D, and the PHPP Excel document. The Rhino3D platform allows for easy creation and manipulation of 3D geometry as well as the associated component meta-data. In addition, Rhino3D has many powerful, freely available plugins that significantly enhance its core functionality. One such plugin relevant to Passive House designers is the popular Ladybug Tools, which allow for comprehensive environmental, solar, and energy analysis by connecting to powerful free tools such as Radiance and EnergyPlus, which are developed and maintained by the U.S. Department of Energy.

Using Honeybee-PH, modelers can create and maintain libraries of complex program data, including lighting, occupancy, and electrical equipment—each with their own schedules of operation and detailed load values. Additionally, Honeybee-PH provides easy access to the full NREL/ OpenStudio commercial program database, which currently features more than 1,700 pre-defined program types within 23 different categories, from retail to datacenters. Honeybee-PH includes custom adapters for converting these hourly-value program types from the NREL library into PHPP formats.

Once created, PHPP modelers can easily assign program types directly to model spaces as required. This information model can be subsequently queried, modified, visualized, and output directly to PHPP as part of the building energy modeling process.

Lighting provides a good example of how Honeybee-PH’s ability to simplify managing data within a 3D BIM environment can decrease modeling time, while improving flexibility and reducing the risk of modeler error.  For many non-residential buildings, electric lighting energy consumption is a key driver of overall site and primary energy use. While the pre-defined lighting loads from the NREL database may be useful during the early design stages, for many buildings the lighting needs to be carefully modeled at the individual fixture scale in order to properly capture the effect on cooling loads and total primary energy demand. This task can be very challenging for large, complex buildings with hundreds or thousands of fixtures, which all need to be tracked throughout the design and construction phases. Honeybee-PH allows modelers to easily model the fixtures within a 3D BIM environment, and the analysis of lighting-power-density (LPD) and construction of the relevant PHPP inputs is then calculated automatically by Honeybee-PH at the space-by-space level. This method of modeling significantly eases the burden of tracking and evaluating LPD. And, Honeybee-PH can also ease the burden of certification compliance, as it can easily output automatic PDFs documenting LPD calculation inputs.

By utilizing Honeybee-PH as part of a BIM-first workflow, Passive House practitioners can significantly decrease model time, reduce errors, and improve the flexibility of their models.