Trial / Demo
As building designers aim for net-zero, passive thermal management strategies have become crucial. Incorporating thermal mass allows buildings to comfortably coast through highs and lows with less demand on the HVAC system. Phase change materials (PCM) offer exceptionally high thermal capacity by absorbing and releasing heat during phase transitions. Armstrong® Templok ceiling tiles integrate PCM that transitions between solid and liquid states near room temperature, passively moderating indoor temperatures and reducing mechanical loads. Through collaboration with Armstrong, Templok ceilings can now be directly evaluated within the latest 2025 release of the IES Virtual Environment (IESVE).
Benchtop and room-scale thermal tests were conducted on the PCM ceiling tiles to develop a thermodynamic model of the material. Using a heat flow meter, the PCM’s specific heat capacity was measured at 1°C increments through its solid, transition, and liquid phases. This detailed heat-capacity profile allows ApacheSim to dynamically update its properties each timestep, accurately representing its thermal behavior in response to its environment.
The PCM model was validated by comparing simulation results to measured data from a physical 13 ft x 13 ft thermal test chamber equipped with a suspended ceiling, return plenum, emulated occupant internal loads, and a heat pump system. Temperature and heat flow measurements were logged throughout the chamber during multiple 24-hour cycles with heating and cooling periods to develop a calibrated model of the chamber in IESVE. Read more about the chamber here. 
CAD model and photograph of the test chamber
First, a model of the chamber was developed in IESVE and calibrated to baseline measurement data without the PCM ceiling. Then, the PCM ceiling was introduced in the physical chamber and in the calibrated model, and the resulting temperature, heat flux, and energy data were compared.
Graphic showing a comparison of the simulated data from the IESVE and the test chamber measurements with and without PCM across a single day
Results from the simulations matched the experiments, affirming the model reliability captures the real-world heat transfer of the PCM ceilings in their installed condition.
The enhanced Plenum/Void Tool within IESVE allows users to efficiently define plenums and apply Templok® ceilings using a Surface Tile Object. With ceiling area coverage adjustable from 0–100%, designers have full control over how much of the ceiling incorporates phase change material (PCM).
Additionally, this tool introduces the capability to model stratified thermal zones—an important feature for evaluating how heat builds and dissipates in spaces with passive thermal storage. By simulating thermal stratification, engineers and modelers can better predict PCM performance, optimize thermal comfort, and reduce HVAC loads in a wide range of building types.
IESVE’s integration with Armstrong HVAC systems provides users with predefined HVAC configurations that are specially calibrated to operate in synergy with Templok® PCM ceilings. These configurations are based on performance benchmarks and best practices developed in partnership with Armstrong to maximize energy efficiency and thermal comfort.
Leveraging these system presets saves time during modeling and ensures that HVAC designs complement the passive energy storage capabilities of the PCM-integrated ceilings. The included User Guide offers detailed instructions for selecting and customizing these systems to suit various project requirements.
VistaPro now includes specialized visualizations for PCM performance metrics, allowing users to track temperature changes and the PCM phase transition behavior in detail. This feature provides a clear visual understanding of how and when the material absorbs or releases heat, directly influencing thermal conditions in a space.
The ability to view PCM activity throughout the simulation timeline helps teams validate their designs, fine-tune zone performance, and demonstrate PCM effectiveness to stakeholders. These insights can drive better-informed decisions around PCM placement, coverage, and HVAC coordination.
With IESVE’s parametric simulation functionality, users can test a wide range of variables to evaluate the impact of PCM ceilings under different conditions. This includes varying the PCM coverage percentage, adjusting HVAC setpoints, experimenting with different internal loads, or altering control strategies.
By running iterative design simulations, architects and engineers can quickly assess trade-offs and optimize building performance for both energy use and occupant comfort. This approach is especially valuable in early-stage design or retrofit evaluations, where flexibility and speed are critical.
Preliminary modeling studies demonstrate significant energy reductions are achievable by substituting Templok ceilings for traditional acoustical ceilings. For example, an office building in Los Angeles modeled a 19% reduction in HVAC energy.
A model small office building in Denver, CO achieved up to 12% total energy savings by adding Templok at a ceiling coverage of 70% and modifying the HVAC controls – a “zero cost” way to further enhance the energy saving benefit of Templok ceilings. Using Templok ceilings only resulted in a 6.7% energy savings.
Ongoing research efforts will continue across various building types and operating conditions to produce more case studies and tips for designing with Templok ceilings in IESVE. Stay tuned for more DiscoverIES articles exploring uses of the new Templok ceilings integration.
Find out more via https://www.iesve.com/software/armstrong-world-industries
