All posts by Daniel Overbey

Blue Roofs are Essential to Achieve Zero Rainwater Overflow

Green Building

Blue Roofs are Essential to Achieve Zero Rainwater Overflow

Originally published on November 30, 2018 by BNP Media through the Building Enclosure Blog. In their latest Infrastructure Report Card, the American Society of Civil Engineers (ASCE) gave our domestic wastewater infrastructure and average grade of D+ citing 772 communities in the US in which wastewater and stormwater drain into the same treatment system. These combined sewer systems can experience capacity issues following heavy rain events, resulting in overflows containing a combination of stormwater with untreated human and industrial waste, toxic substances, debris, and other….

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The Proper Ventilation Rate for an Indoor Environment

Green Building

The Proper Ventilation Rate for an Indoor Environment

Originally published on November 9, 2018 by BNP Media through the Building Enclosure Blog. Ventilation rates in our buildings can be a complicated subject and there is no shortage on ways to assess how air is brought into an indoor environment. Yet, a basic question that commonly emerges is simply: How much ventilation should I provide in a building? ANSI/ASHRAE Standard 62.1 When it comes to defining minimum ventilation rates in buildings (except for low-rise residential), the premiere reference is ANSI/ASHRAE….

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The Health Impacts of Indoor Relative Humidity

Green Building

The Health Impacts of Indoor Relative Humidity

Originally published on October 1, 2018 by BNP Media through the Building Enclosure Blog.   In many parts of the U.S., homeowners with basements have to manage rising humidity levels for most of the cooling season. It is not uncommon for such individuals to have a dehumidifer running full-throttle in the basement from April through October. High indoor humidity levels has been associated with the growth of fungi, such as mold, among other irritants. The EPA suggests keeping indoor relative….

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Clarifying Energy Simulation Aided Design: A Look at ASHRAE Standard 209

Green Building

Clarifying Energy Simulation Aided Design: A Look at ASHRAE Standard 209

Originally published on September 5, 2018 by BNP Media through the Building Enclosure Blog. ANSI/ASHRAE Standard 209-2018, Energy Simulation Aided Design for Buildings Except Low-Rise Residential Buildings is the product of a half-decade of inertia within the building design and construction community toward leveraging energy modeling a design tool through a project. Standard 209 outlines the minimum requirements for providing energy design assistance using building energy simulation and analysis. To this end, the standard defines a range of minimum criteria from energy modeling requirements,….

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How to Make Building Energy Models More Accurate

Green Building

How to Make Building Energy Models More Accurate

Originally published on August 13, 2018 by BNP Media through the Building Enclosure Blog.   I’m asked regularly about the discrepancies between modeled and measured building performance. At first blush, one might suspect that the building energy model (BEM) itself contains bad information. That notion could very well be correct! BEM inputs require a certain level of synthesis, interpretation, and assumption. But there are many other reasons why the BEM results may vary significantly from measured performance outcomes on a completed project. In basic terms: Actual weather in….

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Beware of Galvanic Action (It’s a Thing)

Green Building

Beware of Galvanic Action (It’s a Thing)

Originally published on July 10, 2018 by BNP Media through the Building Enclosure Blog. The concept of “galvanic action” is confounding to many design professionals. In simple terms, galvanic action refers to the corrosive effect created when two electrochemically dissimilar metals are in direct contact with each other. Their contact creates a conductive path for electrons and ions to move from one metal to the other. As ions move from one metal to another, corrosion occurs. The remedy is to….

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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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