Energy Modeling with FineGREEN: A Case StudyAECbytes Tips and Tricks Issue #81 (December 21, 2017)
Vasilios Giotis, ME, MESc PV, BE Mech
Director, BlueGreen Engineering
This article highlights the advantages of using the latest generation of BIM software for energy modeling by the presentation of a specific case study.
The case study was carried out by Blue Green Engineering (BGe), an Australian company with long and extensive experience in Building Energy Design, and refers to an existing building that was constructed back in 2012. The building has an area of around 1000 m² and consists of numerous offices, community and activity rooms, laundry, kitchen and shower facilities, as well as the typical mechanical services.
Regarding the selection of the energy simulation software, BGe considered the following criteria:
- Easy to learn and use Graphical User Interface, preferably similar to AutoCAD™ or IntelliCAD®, given that a familiar interface would assist in reducing the time to learn the software and construct the 3D models.
- Use of the Energy-Plus calculation engine, which is sponsored by the US Department of Energy, and is updated and improved on a regular basis.
- IFC Compatibility to import 3D BIM architectural models from other programs, in a precise and reliable way.
Based on the above criteria, the 4M FineGREEN simulation software package was chosen, due to the following reasons:
- FineGREEN has a familiar CAD user interface (Figure 1) and uses the native DWG format for its files, giving the end user a fairly flat learning curve.
- FineGREEN imports 3D architectural models from programs like Revit®, Archicad®, Vectorworks®, SketchUp Pro® or equivalent, through the IFC import function.
- FineGREEN belongs to a BIM Suite of multi-disciplinary software programs like IDEA for Architectural Design and FINE-MEP for Mechanical /Electrical Services, which also facilitates the sharing of 3D building models.
The final choice decision was empowered by the fact that FineGREEN belongs to the Official EnergyPlus Third-Party Graphical User Interfaces (https://energyplus.net/interfaces#finegreen) and it is also registered within the BEST (Building Energy Software Tools) Directory (https://www.buildingenergysoftwaretools.com/software/finegreen).
Case Study Data and Results
The use of BIM energy modeling software was necessary to determine the annual consumption of the building reliably and efficiently. Energy modeling software saves time when optimally determining building fabric construction and building services. The software is especially beneficial when it reduces time that energy assessors spend running multiple iterations of the calculations.
Regarding the specific project details, Blue Green Engineering (BGe) was commissioned to perform an energy audit for a community services building in Mt. Druitt, NSW, which is operated and owned by the NSW St. Vincent de Paul Society. The building was constructed in 2012. The building’s area was just under 1000 m². The building had numerous offices, community and activity rooms, laundry, kitchen and shower facilities. The mechanical services of the building consisted of the following:
- Central variable refrigeration flow air-conditioning system 25kW cooling capacity
- Central variable refrigeration flow air-conditioning system 7.1 kW cooling capacity
- Air-conditioning system for server room, 3.6 kW
- Air-conditioning system for meeting room, 3.6 kW
- Combined LPG and solar thermal underfloor heating and domestic hot water system
- LPG hot water boiler for showers, 55kW
- Under floor fresh air and ventilation system coupled to high-level motorized openings
Following the Australian Standard 1680.2, the minimum HVAC (heating ventilation and air conditioning) service levels assume a maximum indoor temperature of 24ºC for cooling and 21ºC for heating, as well as a minimum lighting level of 320 LUX for offices, 150 LUX for assembly spaces and 40 LUX for corridors.
The client provided access to 12 months of energy bills. However, due to maintenance issues, many of the service levels were not met because a large number of equipment was not operating. Hence, the energy bills did not reflect the energy baseline accurately (the term ‘energy baseline’, refers to the annual energy consumption of a building before any energy savings upgrades have been implemented).
Therefore, to predict the energy consumption of all the services in the building, two energy models were constructed:
- The first energy model predicted the energy consumption without the service levels being met (as per the actual situation of the building). We used this model to calibrate the energy consumption to the energy bills. Once we were satisfied with the quality of the results from this energy model, we proceeded to the construction of the second energy model.
- The second energy model was based on the first energy model and predicted energy baseline consumption after assuming that all service levels were met and that all maintenance issues had been rectified.
As a result, via this calibrated energy model, it was possible to calculate the baseline energy consumption for a building that met all service levels.
The baseline data was then used to objectively quantify the financial benefits of proposed upgrades. The proposed upgrades included the following:
- Rectify all maintenance issues
- Replace LPG systems with natural gas
- Replace LPG systems with heat-pumps
- Optimize ventilation and HVAC controls
The following figures show the energy modeling process.
Results confirmed that FineGREEN provides a suitable solution for energy modeling on real conditions. More specifically:
- FineGREEN was easy to learn and use, with a functionality that was easily understandable thanks to its familiar, AutoCAD-like graphical interface.
- Due to its BIM philosophy and IFC compatibility, FineGREEN was the optimal tool to import and manipulate 3D BIM building files composed of intelligent objects. The simple graphical interface also facilitated this.
- With FineGREEN, the designer can be confident with the numerical results (intermediate and final), given the well-known reliability of the embedded Energy Plus (e+) calculation engine.
- FineGREEN has the capacity to perform multiple calculations in a fast and reliable manner and at various levels.
For example, in this case study two separate energy models (model 1: energy baseline with the service levels NOT being met; model 2: calibrated energy baseline with the service levels being met) were generated. Therefore, FIneGREEN performed quickly and reliably a large number of calculations for 8.760 hours for a typical year and also performed multiple iterations of the calculations themselves.
For all the above reasons, FineGREEN has led to considerable time-savings as it produced reliable results in a short time which were facilitated by an optimal interface for outputting information into reports.
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