Microclimatic Workflow

OCTOBER | 2022| ISSUE #1

Microclimate Workflow Detailed analysis of climate data to produce customized, interactive visualizations for environmentally informed design

IN THIS ISSUE Introduction Importance for architects to understand the effects of their interventions on indoor and outdoor thermal comfort

Simulation Scenarios Summary of design inferences and the simulation results

Results & Discussions microclimate analysis - A thoroughly integrated design driver for architecture

Introduction

By Anshul Goyal

Over the past two decades, there has been a marked increase in the consideration of outdoor thermal comfort by urban planners.

Several researchers have developed their own models for a better understanding of the human energy exchange with their surrounding environment. Among those models developed is the Ladybug-tools microclimate model, the plugins of Grasshopper3D. These parametric design tools are acknowledged for being time and resource efficient.

This study aims to present a more precise modelling methodology for the outdoor microclimate. The modified model allows for a better parameterization of the outdoor environment and can be considered as rigorous for modelling the outdoor conditions as fully integrated engines, albeit in a significantly less time, allowing parametric optimization of urban geometries to become a viable proposition.

Simulation Scenarios In this study, the models’ performances in different climatic regions are analyzed based on two different locations, namely New Delhi, as a representation for a hot-arid climate, and Brisbane, Australia for a tropical climate. The weather files for both cities were obtained from https://www.ladybug.tools/epwmap/.

universal thermal climate index. Comfort. Air Movement is an effective strategy for adaptive thermal especially in July - October period.

Prevailing wind direction during this period is EastWest.

(Above) Annual UTCI heat maps for Brisbane, Australia.

(Above) Annual UTCI heat maps for New Delhi, India The vertical dimension indicates the time of day, and the horizontal dimension indicates time of year.

Some inference from Delhi UTCI is April to October are months with high temperatures averaging over 30 C. 42% of annual hours are deemed uncomfortable according to

The vertical dimension indicates the time of day, and the horizontal dimension indicates time of year.

Some inference that from Brisbane UTCI is Oct to Mar are months with high diurnal temperatures averaging over 30 C. 26.68 % of annual hours are deemed uncomfortable according to universal thermal climate index

Windrose (Oct-Mar) Air Movement is an effective strategy for adaptive thermal comfort, especially in Oct-Mar period.

Prevailing wind direction during this period is Northeast- Southeast

sun will work for New Delhi, which lies in above equator but apparently will not work for Brisbane.

Direct Solar radiation.

Psychometric Chart The psychometric chart can be a wonderful tool for understanding the relationships between temperature vs. humidity, and can be used to express human thermal comfort, design strategies, and energy requirements for those strategies.

With the help of ladybug plugins, one can quickly quantify the solar energy falling on building geometry. (Above) Brisbane graphic shows the maximum amount of solar radiation from northwest to northeast. By overlapping the sun's path on top of the solar dome one can identify and mitigate solar heat as per the period in which the respective building functions.

Similarly, the dome for New Delhi shows the maximum radiation coming from the south. The interesting thing here is the difference in the hemisphere for New Delhi & Brisbane, Meaning the strategies being applied to cut dominant southern

(Above) Psychometric chart for New Delhi, India.

Since the maximum number of hours falls outside the comfortable range (Blue). Some strategies like shading, Air movement play an important role as stated above can increase the percentage of comfortable hours (Red). Even though the temperature will be higher between 35-40 deg there will be thermal comfort by using passive strategies like evaporative cooling, and enhanced wind movement.

(Above) Psychometric chart for Brisbane

As the psychometric chart implies the maximum number of hours fall under the comfortable range i.e., 24-26 deg, Strategies like sun shading for the mentioned direction can further optimize comfortable hours for Brisbane.

Results & Discussions The efficient and synergistic use of simulation tools is only part of the effort required to incorporate microclimate as a design driver of architecture.

Equally relevant to this discussion is the process of linking simulation results to design interventions.

This occurs in three steps.

• • •

Recognizing the type of thermal discomfort. zeroing in on the environmental parameters causing that discomfort, and Designing interventions that manipulate those environmental parameters.

For example, if a simulation reveals a prevalence of cold stress in an outdoor patio during a mostly comfortable season, possible culprits are the wind (which controls the rate of convective cooling on individuals’ skin) or the MRT (which determines the radiative heat balance between an individual and the environment).

With this knowledge, an architect may choose to add wind-blocking landscape features while rearranging the building massing to allow more direct sunlight onto the patio. Alternatively, this analysis may reveal a naturally more comfortable location for the outdoor amenity To definitively assess a design in terms of microclimate, it is important to consider the thermal comfort of space for the entire period of use as opposed to just a point in time.