Building Envelope Systems and Assemblies

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Questions and Answers

Which of the following BEST describes the primary function of a building envelope?

  • To solely provide structural support for the building.
  • To separate the interior of a building from its exterior environment. (correct)
  • To maximize the use of glass in the building's design.
  • To serve only as an aesthetic feature of the building.

Which components are integral to a building envelope?

  • Walls, roofs, and fenestration (correct)
  • Interior decorations, furniture, and appliances
  • Landscaping, walkways, and driveways
  • HVAC systems, plumbing, and electrical wiring

What is the main goal of energy-efficient building envelopes?

  • To act as simple barriers between the interior and exterior.
  • To create comfortable spaces and substantially reduce energy consumption. (correct)
  • To maximize the use of non-renewable resources.
  • To disregard the building's external environment.

In regions with high humidity, like the Philippines, what is a crucial consideration for building design?

<p>Ensuring maximum air tightness to prevent humidity ingress. (B)</p> Signup and view all the answers

What specific construction details should be precisely included to maximize air tightness?

<p>Joints, service entry points, windows, and doors. (B)</p> Signup and view all the answers

Why is it ideal to reduce the amount of glazing compared to wall assemblies?

<p>Glazing transfers more heat, leading to increased internal heat gains. (A)</p> Signup and view all the answers

What is the purpose of balancing the Window to Wall Ratio (WWR)?

<p>To balance the amount of daylight coming through the glazed area. (C)</p> Signup and view all the answers

What does the Solar Heat Gain Coefficient (SHGC) measure?

<p>The amount of solar heat admitted through the glass divided by the total solar radiation incident on the glass. (C)</p> Signup and view all the answers

What does Visible Light Transmittance (VLT) indicate?

<p>The amount of light transmitted through the glass. (C)</p> Signup and view all the answers

According to the provided table, what is the maximum SHGC for a Window to Wall Ratio (WWR) of 50?

<p>0.44 (C)</p> Signup and view all the answers

According to the provided table, what is the minimum VLT for a Window to Wall Ratio (WWR) of 60?

<p>0.50 (D)</p> Signup and view all the answers

What benefit does natural ventilation offer to building occupants?

<p>Provides free cooling and fresh air. (C)</p> Signup and view all the answers

What aspect of a room should be consistent with the occupancy load according to the NBC (National Building Code)?

<p>Size (C)</p> Signup and view all the answers

How does using a light-colored building envelope reduce heat transfer?

<p>By having surfaces with high Solar Reflectance Index (SRI). (B)</p> Signup and view all the answers

Which part of the building envelope is most vulnerable to heat transfer?

<p>Roof areas (C)</p> Signup and view all the answers

According to the Solar Reflectance Index Values table provided, which metal surface has the highest SRI value?

<p>Reflective White (C)</p> Signup and view all the answers

What is the primary function of roof insulation?

<p>To prevent heat gain in a building. (C)</p> Signup and view all the answers

What is the purpose of R-value in the context of thermal insulation?

<p>To measure the ability to resist heat transfer. (C)</p> Signup and view all the answers

Which of the following statements is correct regarding the relationship between R-value and insulation effectiveness?

<p>The higher the R-value, the better the insulation. (C)</p> Signup and view all the answers

What is RSI in relation to R-value?

<p>The metric equivalent of measuring thermal resistance. (A)</p> Signup and view all the answers

According to the provided table, which insulation material has the highest R-value per inch?

<p>Polyurethane (D)</p> Signup and view all the answers

According to the provided table, what is the R-Value/inch of Plastic Fiber?

<p>4.3 (D)</p> Signup and view all the answers

Which of the following materials is NOT typically used as insulation?

<p>Concrete (A)</p> Signup and view all the answers

What is the function of insulation?

<p>To trap gases, reducing conduction and convection heat transfer. (B)</p> Signup and view all the answers

Which of these is NOT a primary type of insulation?

<p>Liquid foam (A)</p> Signup and view all the answers

According to the image, where is a common location to insulate a residence?

<p>Between the studs and rafters of exterior walls (A)</p> Signup and view all the answers

Where should insulation be placed in unfinished attic spaces?

<p>Between the ceiling joists to seal off living spaces below (B)</p> Signup and view all the answers

Besides wall between living spaces and unheated garages, where should insulation be placed for all exterior walls?

<p>Foundation walls above ground level (C)</p> Signup and view all the answers

Where should insulation be placed in floors above cold spaces?

<p>Foundation walls of crawl spaces and perimeter plates (C)</p> Signup and view all the answers

Why should well-insulated attics, crawl spaces, and storage areas be adequately ventilated?

<p>To prevent excessive moisture buildup. (C)</p> Signup and view all the answers

What is the significance of insulating slab floors built directly on the ground?

<p>Almost always insulated, according to building codes. (A)</p> Signup and view all the answers

What materials are windows constructed of?

<p>Glazing (glass) and frame (B)</p> Signup and view all the answers

What is 'glazing' in the context of window construction?

<p>Translucent or transparent materials (i.e., glass and some plastics) that allow light to pass through. (C)</p> Signup and view all the answers

How can the type of glazing used in a window or skylight affect a building?

<p>It can have a dramatic effect on energy performance. (C)</p> Signup and view all the answers

WHICH of the following hypothetical scenarios would MOST severely compromise a building envelope's ability to regulate internal temperature and moisture, leading to potential structural and health issues?

<p>Complete failure of the vapor barrier in ALL exterior walls of a building in a climate zone with extremely cold winters and humid summers. (D)</p> Signup and view all the answers

Imagine a high-rise building in a tropical climate is designed with a uniform Window-to-Wall Ratio (WWR) on all facades. However, due to budget constraints, the building owner opts for a single type of glazing with a fixed Solar Heat Gain Coefficient (SHGC) and Visible Light Transmittance (VLT) for all windows. Assuming all other design elements remain constant, which of the followwing situations is MOST likely to occur?

<p>The building's cooling load will be higher than anticipated due to excessive solar heat gain, particularly on the east and west facades. (B)</p> Signup and view all the answers

Flashcards

Building Envelope System or Assembly

Parts of a building that separate the interior from the exterior, controlling heat, air, and moisture flow.

Energy-Efficient Envelopes

Building systems that create comfortable spaces by actively responding to the building's external environment and reducing energy consumption.

Air Tightness and Moisture Protection

Maximizing air tightness, especially at joints, service entry points, windows, and doors, to prevent humidity ingress.

Glazing Heat Transfer

Glass can transfer more heat than wall assemblies, making it ideal to reduce the amount of glazing to reduce internal heat gains.

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Window to Wall Ratio (WWR)

The ratio of window area to wall area; balancing it is important for daylighting.

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Solar Heat Gain Coefficient (SHGC)

The amount of solar heat admitted through glass divided by the total solar radiation.

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Visible Light Transmittance (VLT)

The amount of light transmitted through the glass.

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Natural Ventilation

Providing occupants with the ability to use outside air rather than air conditioning by opening windows.

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Light-Colored Envelopes

Light-colored envelopes reduce heat transfer from outside to inside, especially on roofs.

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Solar Reflectance Index (SRI)

A measure of a material's ability to reflect solar energy; High SRI means less heat absorption.

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Roof Insulation

Reduce heat gain, improve thermal comfort, improve acoustic quality and reduce air conditioning load.

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Thermal Insulation

Material that resists heat transfer.

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R-Value

Measure of insulation's ability to resist heat transfer.

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Insulation

Material installed to reduce heat loss/gain.

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Insulation Materials

Fiberglass, cellulose, mineral wool, foam, fiberboard.

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Types of Insulation

Blankets, batts, rolls, loose-fill, spray applied, rigid, reflective.

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Windows

Glazing (glass) and frame that allows light to pass through the building envelope.

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Glazings

Translucent/transparent materials like glass or plastics that allow light to pass through.

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Study Notes

  • Building Envelope Systems and Assemblies involve understanding the selection and application of building envelope systems
  • Building envelope systems are relative to performance, aesthetics, moisture transfer, durability, and energy and material resources

Building Envelope System or Assembly

  • Parts of a building that separate the interior from the exterior
  • Walls, roofs, and fenestration control the flow of heat, air, and moisture.

Building Envelope & Energy Efficiency

  • Energy-efficient building envelopes create comfortable spaces by actively responding to the building's external environment
  • Building envelopes substantially reduce the buildings' energy consumption

Air Tightness and Moisture Protection

  • High humidity levels can cause issues with air conditioning and air quality
  • Maximizing air tightness is important in building design
  • Specific details like joints, service entry points, windows, and doors need precise planning
  • Implementing air tightness measures requires attention to construction details at practically no extra cost

Glass Properties

  • Glazing transfers more heat, so reducing glazing in relation to walls can reduce internal heat gains
  • Window to Wall Ratio (WWR) must be balanced with the amount of daylight
  • Solar Heat Gain Coefficient (SHGC) determines the solar heat admitted through the glass divided by the total solar radiation incident
  • Visible Light Transmittance (VLT) determines the amount of light transmitted through the glass

SHGC and VLT for Different WWR

  • WWR of 10 has a max SHGC of 0.80 and a min VLT of 0.80
  • WWR of 20 has a max SHGC of 0.70 and a min VLT of 0.70
  • WWR of 30 has a max SHGC of 0.60 and a min VLT of 0.70
  • WWR of 40 has a max SHGC of 0.45 and a min VLT of 0.60
  • WWR of 50 has a max SHGC of 0.44 and a min VLT of 0.55
  • WWR of 60 has a max SHGC of 0.37 and a min VLT of 0.50
  • WWR of 70 has a max SHGC of 0.31 and a min VLT of 0.45
  • WWR of 80 has a max SHGC of 0.27 and a min VLT of 0.40
  • WWR of 90 has a max SHGC of 0.24 and a min VLT of 0.35

Natural Ventilation

  • Natural ventilation provides flexibility and opportunity for free cooling and fresh air
  • Natural ventilation limits the need to create glass sealed box type buildings
  • Room size and space size shall be consistent with the occupancy load of the NBC (National Building Code)

Building Envelope Color

  • Light-colored building envelopes, especially in roof areas, reduce heat transfer
  • Surfaces with high Solar Reflectance Index (SRI) reduce heat transfer

Solar Reflectance Index (SRI) Values of Basic Colored Coatings

  • Reflective White has an SRI of 86 to 92
  • Basic White has an SRI of 80 to 88
  • Beige/Tan has an SRI of 74 to 80
  • Dark brown has an SRI of 0 to 33
  • Light to medium brown has an SRI of 45 to 56
  • Light to medium grey has an SRI of 39 to 63
  • Dark grey has an SRI of 0 to 41
  • Blue has an SRI of 23 to 30
  • Red has an SRI of 28 to 36
  • Green has an SRI of 25 to 32
  • Light to medium green has an SRI of 30 to 48

Roof Insulation

  • Insulation helps reduce heat gain in a building
  • Insulation improves thermal comfort and acoustic quality
  • Insulation reduces the load on the air conditioning system

Thermal Insulation

  • R-value (resistance-value) rates insulation products based on their ability to resist heat transfer
  • R-value is expressed in units of °C · (hr °F · )
  • The higher the R-value, the better the insulation
  • RSI is the metric equivalent, about 1/6th of the R-value
  • 1.0 hr °F · = 0.1761 °C
  • R = 0.1761 RSI
  • RSI = 5.679 R

R-Value of Common Roof Insulation

  • Polyurethane has an R-Value/inch of 5.6 to 6.5
  • Phenolic foam has an R-Value/inch of 4.8
  • Plastic Fiber has an R-Value/inch of 4.3
  • Mineral Fiber has an R-Value/inch of 4.2 to 4.5
  • Fiberglass has an R-Value/inch of 3.7
  • Rockwool has an R-Value/inch of 3.7
  • Rigid foam has an R-Value/inch of 3.6 to 6.7
  • Hemp has an R-Value/inch of 3.5
  • Cotton has an R-Value/inch of 3.4
  • Straw has an R-Value/inch of 2.4 to 3.0
  • Sheep’s wool has an R-Value/inch of 3.5
  • Mineral wool has an R-Value/inch of 2.8 to 3.7

Insulation

  • Insulation like fiberglass, cellulose, mineral wool, foam, or fiberboard reduces heat loss or gain
  • Insulation traps gases (e.g., air) to reduce conduction and convection heat transfer

Types of Insulation

  • Blankets, batts, or rolls
  • Loose-fill/spray applied
  • Rigid insulation
  • Reflective insulation

Windows

  • Windows affect building envelope properties like heat transfer, ventilation, and passive solar heating/cooling
  • Windows constructed of glazing (glass) and frame
  • Glazings (translucent or transparent materials like glass and plastics) allow light to pass through a building envelope
  • The type of glazing impacts energy performance

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