Tag Archives: Environmental Systems

The Psychrometric Chart Explained

Green Building

The Psychrometric Chart Explained

Originally published on June 13, 2018 by BNP Media through the Building Enclosure Blog. It is one of the intimidating charts for any building design professional: the psychrometric chart. At first blush, the “psych chart” looks very complicated. There are layers of axes and curved reference lines. However, a closer examination will reveal that – at its essence – the chart is visually conveying the answers to two related questions: How much sensible (dry-bulb) heat is in the air? (See….

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Dry-Bulb Temperature, Wet-Bulb Temperature and Enthalpy

Green Building

Dry-Bulb Temperature, Wet-Bulb Temperature and Enthalpy

Originally published on May 9, 2018 by BNP Media through the Building Enclosure Blog. There is energy in the air all around us. Some of it exists in the form of thermal energy that one can sense – heat in air that impacts one’s perception of thermal comfort. But there is also an energy embodied in the vapor present in the air. While this “hidden” heat is not experienced as warmth, it certainly has a bearing on thermal comfort as….

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Defining Humidity Ratio and Relative Humidity

Green Building

Defining Humidity Ratio and Relative Humidity

Originally published on April 4, 2018 by BNP Media through the Building Enclosure Blog. How does a hot-air balloon rise? Fire up the burner and the temperature of the air captured within the balloon increased. The molecules of the air take on the thermal energy and become more excited. The excited molecules create more space between them. As a result, the air expands as its temperature increases. Thus, one pound of air at 80-degrees Fahrenheit (°F) is a larger volume than….

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Thermal Dynamics: Visualizing Sensible Versus Latent Heat

Green Building

Thermal Dynamics: Visualizing Sensible Versus Latent Heat

Originally published on March 12, 2018 by BNP Media through the Building Enclosure Blog. It’s the first law of thermodynamics. The Law of Conservation of Energy states that energy can neither be created nor destroyed; energy can only be transferred or changed from one form to another. This is the foundation of phase change in the physical environment. Molecular activity requires energy. The activity does not just magically happen. Phase Change When a material changes its state or phase (e.g., going….

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Applets for Energy and Environmental Design

Green Building

Applets for Energy and Environmental Design

Originally published on July 10, 2017 by BNP Media through the Building Enclosure Blog. Newsflash: There are a lot of great (and free) online resources for design professionals. When I am having exchanges about energy and environmental design analysis with colleagues and students, it seems like I am constantly referring them to any number of small, accessible online utility programs for performing simple – yet highly sophisticated – functions. Some would refer to these small programs as applets. Below, I have….

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Analog Analysis

Green Building

Analog Analysis

Lam Partners Principal Keith Yancey demonstrates model testing on the heliodon with students at the Boston Architectural College during the Fall 2015 Intensive Week. Photograph by Daniel Overbey. Originally published on August 25, 2015 by BNP Media through the Walls & Ceilings Blog. Digital tools are vital (I rely on them virtually everyday), but sometimes in order to really understand a phenomena we have to get a bit closer. That’s where analog analysis tools come in handy. Something special happens when….

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When the ‘Prevailing’ Wind Direction is Anything But

Green Building

When the ‘Prevailing’ Wind Direction is Anything But

Originally published on June 1, 2015 by BNP Media through the Walls & Ceilings Blog. The wind rose is a conventional diagram for characterizing both the direction and frequency of wind around a project site. This graphic is commonly included in a climate data analysis. Some software platforms such as Climate Consultant, one of several free energy analysis tools developed and released through the University of California, Los Angeles (UCLA) Department of Architecture & Urban Design, can generate wind roses….

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