Air Conditioning & Ventilation Basics
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Match the following techniques with their purpose in reducing cooling loads:

Insulate Wall, Insulate roof = Reducing Radiative Gain Internal Blinds = Reducing Direct Gain SUN-SHADING DEVICES (brise soleil) = Reducing Conductive Gain SHADING COEFFICIENT = Reducing Indirect Gain

Match the following formulas with their respective heat gain calculations:

QS = No: of people x Sensible heat gain per person x CLF = Heat Gain from People (Sensible Heat) QL = No: of people × Latent heat gain per person = Heat Gain from People (Latent Heat) Q = Btu/hr × Ballast factor × CLF = Heat Gain from Lighting SHADING COEFFICIENT = 1.0 for 1/8 inch (3mm) thick clear glass = Shading Coefficient Calculation

Match the following with their definitions:

Shading Coefficient (SC) = A measure used to quantify the solar heat gain of glass Conductive Gain = Heat gain through walls and roofs Radiative Gain = Heat gain from solar radiation Indirect Gain = Heat gain from internal loads

Match the following with their role in thermal comfort:

<p>Air Temperature = Influences the sensation of warmth or coolness Relative Humidity = Affects the perception of temperature Air Movement = Influences the evaporation of sweat and heat loss Conditioning Strategies = Methods to achieve thermal comfort</p> Signup and view all the answers

Match the following with their purpose in reducing cooling loads:

<p>SUN-SHADING DEVICES (brise soleil) = Reducing Direct Gain Internal Blinds = Reducing Indirect Gain Insulate Wall, Insulate roof = Reducing Conductive Gain SHADING COEFFICIENT = Reducing Radiative Gain</p> Signup and view all the answers

Match the following formulas with their respective units:

<p>QS = No: of people x Sensible heat gain per person x CLF = Btu/hrt QL = No: of people × Latent heat gain per person = Btu/hr Q = Btu/hr × Ballast factor × CLF = Watts SHADING COEFFICIENT = 1.0 for 1/8 inch (3mm) thick clear glass = Dimensionless</p> Signup and view all the answers

Match the following with their effects on thermal comfort:

<p>High Air Temperature = Increases heat gain Low Relative Humidity = Increases evaporation of sweat Low Air Movement = Reduces heat loss High Shading Coefficient = Increases solar heat gain</p> Signup and view all the answers

Match the following with their methods to reduce cooling loads:

<p>Insulate Wall, Insulate roof = Passive Design Strategy SUN-SHADING DEVICES (brise soleil) = Active Design Strategy Internal Blinds = Building Orientation Strategy SHADING COEFFICIENT = Window Shading Strategy</p> Signup and view all the answers

Match the following with their heat gain calculations:

<p>QS = No: of people x Sensible heat gain per person x CLF = Heat Gain from Occupants QL = No: of people × Latent heat gain per person = Heat Gain from Lighting Q = Btu/hr × Ballast factor × CLF = Heat Gain from Equipment SHADING COEFFICIENT = 1.0 for 1/8 inch (3mm) thick clear glass = Heat Gain from Windows</p> Signup and view all the answers

Match the following with their thermal comfort parameters:

<p>Air Temperature = Thermal Comfort Parameter Relative Humidity = Thermal Comfort Parameter Air Movement = Thermal Comfort Parameter SHADING COEFFICIENT = Thermal Comfort Factor</p> Signup and view all the answers

Study Notes

Air Conditioning & Ventilation Overview

  • Air conditioning adjusts air properties, particularly temperature and humidity, to enhance comfort.
  • Key components influencing thermal comfort include air temperature, humidity, mean radiant temperature, air movement, metabolic rate, and clo value.

Passive and Active Systems

  • Passive Systems utilize natural forces (e.g., cross ventilation, thermal mass, night ventilation).
  • Active Systems require energy input (e.g., Mechanical Ventilation and Air Conditioning (MVAC), radiant cooling).

Passive Design Principles

  • Building Orientation: Positioning buildings to optimize solar exposure and wind patterns.
  • Building Form: Design shapes that facilitate natural ventilation and reduce heat absorption.
  • Shading Elements: Incorporate architectural features to mitigate direct solar gain.
  • Building Materials: Select materials with appropriate thermal resistance and insulation properties.
  • Window Characteristics: Use windows that enhance natural light while minimizing heat gain.
  • Vegetation: Utilize landscaping elements, both exterior and interior, to provide cooling effects.
  • Daylighting: Maximize natural light penetration while reducing reliance on artificial lighting.

Thermal Comfort Research

  • Studies by Houghten and Yagloglou, conducted in 1927, identified three key parameters for assessing thermal comfort:
    • Dry bulb temperature (DBT)
    • Wet bulb temperature (WBT)
    • Air velocity

Internal Gains and Heat Transfer

  • Solar Gain: The increase of heat from solar radiation through windows and other elements.
  • Internal Gain: Heat produced within a space from occupants, lighting, and equipment.
  • Cooling Load Calculations:
    • Sensible heat gain from occupants, calculated as ( Q_s = \text{No. of people} \times \text{Sensible heat gain/person} \times \text{CLF} ).
    • Latent heat gain follows a similar formula, focusing on moisture.

Shading and Heat Gain

  • Sun-shading devices, such as brise soleil, lower solar heat gain and reduce glare.
  • The Shading Coefficient (SC) quantifies the heat gain of glass in comparison to standard clear glass.

Reducing Cooling Loads

  • Strategies to minimize conductive heat gain include:
    • Insulating walls and roofs to improve thermal performance.

Cooling Load from Lighting

  • Lighting heat gain is computed using the formula ( Q = \text{Btu/hr} \times \text{Ballast factor} \times \text{CLF} ), where the ballast factor varies by type of lighting.

Key Formulas

  • Sensible Heat Gain Equation:
    • ( Q_{\text{sensible}} = \text{Number of people} \times 75 \text{W/person} )
  • Latent Heat Gain Equation:
    • ( Q_{\text{latent}} = \text{Number of people} \times 55 \text{W/person} )

These study notes summarize critical insights on air conditioning systems, ventilation strategies, and thermal comfort considerations, important for building design and environmental control.

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Description

Learn about the principles of air conditioning and ventilation, including passive and active systems that enhance thermal comfort by adjusting temperature, humidity, and air movement.

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