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Buildings use around 30% of the world’s energy and cause about 28% of global CO₂ emissions, mainly due to heating and cooling. As cities grow and the climate warms, it’s more important than ever to make buildings energy-efficient. That’s where building energy models (BEMs) come in — they help us design buildings that use less energy.
To make these models more accurate, you can now combine them with ENVI-met, a tool that simulates the local microclimate around buildings. This article explains how adding ENVI-met data to tools like EnergyPlus, IES-VE, and TRNSYS can improve your energy simulations.
What is ENVI-met?
ENVI-met is a 3D microclimate simulation tool designed to model interactions between buildings, vegetation, surfaces, and atmospheric conditions. It is widely used in urban design and environmental analysis to assess the impact of planning decisions on local climates. ENVI-met generates comprehensive data on:- Air temperature
- Wind speed and direction
- Shortwave and longwave radiation fluxes
- Relative humidity
- Surface and wall temperatures
- Turbulence and heat fluxes
- Simulate short- and long-wave radiation, including shading and reflections, to create spaces that reduce heat stress.
- Analyse surface temperatures of roofs and facades to support energy efficiency and thermal comfort.
- Integrate green roofs, facades, and water features to lower urban temperatures and boost sustainability.
- Model plant physiology and water stress to maximize the cooling and environmental benefits of greenery.
Fig. 1: ENVI-met enables users to create 3D models of urban landscapes, incorporating buildings, natural and artificial surfaces, vegetation, and water features.
How ENVI-met improves building energy simulations
Traditional building energy simulation (BES) tools rely on standardized weather station datasets (e.g., TMY, IWEC, EPW files) to define key boundary conditions such as air temperature, solar radiation, and wind speed. These inputs are essential for predicting heating, cooling, and ventilation loads. However, the generic climate files these standardized datasets contain fail to capture local microclimatic variations, leading to discrepancies between simulated and actual building performance.
Urban overheating is real — and standard datasets often miss the mark
For example, imagine a building located in an urban canyon — a narrow street surrounded by tall buildings with limited airflow. Now compare that to a building next to a large green park. The thermal conditions are completely different, yet traditional modelling tools can struggle to reflect these nuances.The solution? Add ENVI-met to your toolkit.
By incorporating ENVI-met’s microclimate simulation results into Building Energy Simulation (BES) models, you gain a much more accurate understanding of a site’s real environmental context. That means:
- Better energy performance predictions
- More informed design decisions
- Greater thermal comfort for occupants
Research supports this approach. A study conducted by researchers from the United Arab Emirates University and Newcastle University compared urban-specific weather datasets (USWDs) generated with ENVI-met against typical meteorological year (TMY) data in IES-VE. Their findings showed that using USWDs reduced BES prediction errors by 60% compared to TMY-based models.
Key advantages of integrating ENVI-met with building energy simulations
ENVI-met helps generate precise input data for building energy simulations. The key benefits of using this data include:
Accurate outdoor air temperature inputs: ENVI-met simulates high-resolution, localized air temperature data, replacing generic climate files for more precise modeling.
Accurate outdoor air temperature inputs
ENVI-met simulates high-resolution, localized air temperature data, replacing generic climate files for more precise modeling. ENVI-met enables easy analysis of air, surface, and façade temperatures across different urban and meteorological conditions (See figure below).
Comprehensive radiation modeling
ENVI-met simulates both longwave and shortwave radiation fluxes in urban environments with high resolution. This allows for precise calculations of radiative loads on building façades based on orientation, shading, and the surrounding urban context. High-resolution radiation flux calculations help determine external building energy loads (see figure below).
Realistic wind flow and natural ventilation simulation
By capturing complex wind variations in urban areas, ENVI-met provides a more accurate assessment of ventilation effects on buildings. With computational fluid dynamics, ENVI-met enables wind simulations at resolutions as fine as 1 meter (see figure below).
Simulation of natural impacts
As a holistic model, ENVI-met accounts for urban vegetation’s role in shading and transpiration, which significantly influences local microclimates. ENVI-met provides a detailed view of how vegetation impacts urban spaces and buildings (see figure below).
Conclusion
ENVI-met is a high-resolution microclimate simulation tool that enhances building energy models with localized environmental data. By integrating ENVI-met with Building Energy Simulation (BES) tools like EnergyPlus, IES-VE, or TRNSYS, designers can make informed decisions tailored to specific urban conditions.
From assessing urban heat island effects and optimizing façade radiation exposure to evaluating site-specific wind and ventilation strategies, ENVI-met refines energy simulations beyond standard climate files. This enables architects and engineers to design energy-efficient buildings that reduce operational energy demand while improving occupant comfort.
For more information on how ENVI-met can support healthier urban design, visit ENVI-met from One Click LCA.
