DIALOG is an integrated design firm offering architecture, structural, mechanical & electrical engineering, interior design, urban design, and landscape architecture services. They are passionate designers who believe in the power of the built form to meaningfully improve the wellbeing of our communities and the environment we all share.
Alexander Tansowny, a budding building energy analyst at DIALOG, is pioneering the use of IES’ new ERGON tool to accurately quantify energy and CO2 savings of high performing HVAC systems.
Using the integration between ERGON and the IESVE suite of building performance analysis tools, he successfully modelled several innovative and creative HVAC systems, including an exhaust air heat recovery system as part of an entry into a building simulation competition and a unique chilled water economizing system for a hospital targeting LEED® Silver certification.
Alexander developed a two-step process to feed simulated data back into the model to improve the accuracy. In a second simulation, hourly results from the first preliminary simulation become inputs using the free-form profile tool ERGON.
“Previously, the only way to model these unique, high-performing HVAC systems was to use spreadsheets. Now the IES ERGON tool provides a streamlined process, that is also less prone to error with easy results viewing in VistaPro,” commented Alexander. “I’m confident now that I’ve been able to model these systems with greater accuracy and better quantify the energy and CO2 savings of such high performance HVAC systems.”
For the competition entry, all of the IESVE and ERGON features were required. The design included a dedicated outdoor air unit with heating provided by an air source heat pump. This system was unique because the heat pump was configured to transfer energy from the building exhaust air to the supply air.
Modelling this system was a challenge as it was critical to use hourly exhaust air temperature data to accurately predict heat pump efficiency. To model the heat recovery heat pump, an initial simulation with a generic heat source serving the heating coil in the supply air stream was run.
This was done with the system in its final configuration so that exhaust air temperatures were accurate including the effect of all system components. Hourly exhaust air temperatures were imported into the free form profile-generating tool ERGON. With the exhaust air temperature data in a format to be used by IES, the final simulation could be done.
The final simulation of the exhaust air heat recovery heat pump was completed with a water source heat pump component within the VE. The annual hourly exhaust air temperature profile was applied as the source water temperature as to capture the actual efficiency of the heat recovery heat pump.
“Modelling to this level of accuracy is important because high performance buildings are moving towards absolute energy and greenhouse gas emission targets. Designing to an absolute target holds the accuracy of an energy model to a higher standard in contrast to comparing a proposed design to a reference case. Fully accounting for the details of a system design will help to close the performance gap between modelled and actual performance.” added Alexander.
Alexander also used this two-step modelling technique to simulate a seasonal chilled water economizing system for a LEED® Silver Hospital project. Here he combined simulation results in the form of a free-form profile with the scheduled load functionality on a chilled water loop. During the winter a waterside economizer provides process cooling for the facility but in the summer the load is served by the chiller plant. A summer and winter cooling system was modelled for the process cooling loop. After the preliminary simulation, the chilled water load on the summer process loop was processed into a
free-form profile using ERGON and applied to the building chiller plant using the scheduled load functionality.
“This is not just a one off use. ERGON combined with the scheduled load functionality on chilled and now hot water loops in VE2017 allows us a lot more flexibility to handle unique HVAC systems with the software.” W. Alexander Tansowny EIT LEED® AP BD+C, Building Energy Analyst, DIALOG.