Module 3 Lesson 2 CE 104 - Building Systems Design-converted PDF

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Module 3 Lesson 2Welcome to Module 3 Lesson 2!Building Envelope Systems and Assemblies:Moisture Transfer Durability, Energy and Material ResourcesIntroduction to the TopicThe building sector accounts for 36% of national energy consumption (2010). About 50% to 70% of building energy is used for mecha...

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Module 3 Lesson 2

Welcome to Module 3 Lesson 2! Building Envelope Systems and Assemblies: Moisture Transfer Durability, Energy and Material Resources Introduction to the Topic The building sector accounts for 36% of national energy consumption (2010). About 50% to 70% of building energy is used for mechanical systems such as airconditioning and ventilation systems. The Philippine Green Building Code requires the adoption of efficient practices, designs, methods, and technology that can reduce energy consumption resulting in cost savings, reduced energy consumption, and reduced GHG emissions. Energy-efficient practices and technology can contribute to achieving green building objectives.

Intended Learning Outcomes: At the end of the session, students will be able to: 1. Understand the importance of consideration of moisture protection in building design; and 2. Familiar with building envelope energy flow, heat transfer, and materials.

Discussions: Building envelope physically separates the indoor and outdoor environments. It encompasses the entire exterior surface of a building, including walls, roof, doors, and windows, which enclose, or envelope, the interior spaces. It is composed of layers of building materials that protect interior spaces from changes in outdoor weather and climate conditions. Some elements of a building envelope include:

The following illustrates how a building envelope acts as a barrier between outdoor and indoor conditions.

Air Tightness and Moisture Protection As the country’s humidity levels are high, the unwanted air infiltration and moisture ingress into indoor spaces can put additional load on the air-conditioning system and cause a detrimental impact on air quality. Thus, buildings must be planned, designed, and constructed with enough detail and quality to ensure maximum airtightness. The implementation of these measures requires only increased attention to the construction details and it can be implemented at practically no cost. Details should precisely include joints, including service entry joints, windows, and doors. Vapor barrier, a material that has a permeance of one perm or less, can also be installed. It prevents the entry of moisture through the walls and provides resistance to the transmission of water vapor from the outside to the inside of the building, which can burden the air-conditioning system operations.

Design Application 1. SEALED WINDOW AND DOOR ASSEMBLIES: sealed by a continuous

membrane along the joints between wall and window and door frames. Window

and door assemblies should be complete with weather stripping and gaskets around the frames. Doors and windows are the first line of defense against humidity and moisture.

Installation of airtightness of different weather stripping for flooring and door frames

Window assembly with sealant installation all-around and between glass panels and frames.

2. SEALED UTILITY SERVICES: Electrical, plumbing and mechanical piping, conduit or ducting penetrating through walls, floor, and ceiling should be sealed to

reduce air leakage. Joints in the membrane should be caulked, lapped, and sealed or taped. 3. SEALED WALL, ROOFING, CEILING, AND FLOOR: tightly sealed with continuous water barrier or retarder, joint flashing, capping, sealants, and fillers. 1. WALL - sealed with the application of a vapor/moisture barrier 2. ROOF - sealed with complete ridge roll, flashing, valley, and joint terminations 3. CEILING - joints and openings sealed with tape 4. FLOOR - floor surfaces, joints, and terminations sealed with the application of water barrier, joint fillers, or airtightness tape. Waterproofing membrane overexposed roof or deck slabs while water barrier sheathing underexposed floor slabs on fill.

Duct penetration through wall ready to receive sealing material. This is to prevent the transfer of air and moisture between spaces.

Roof The roof shields a structure from harsh elements from sunshine to rain, so it is important to seal off and reinforce it.

Metal roof edge flashing with rubber closure strips to seal ends, valleys, and joint terminations for airtightness.

Air tightness at Roof Ridge

150 mm

UK.

LOAD

BEARINC CHB WALL FIREWALL

MORTAR

CA 24 PREPAIh TE0 G.I. COUNTERFLASHING FASTEHED TO CHB ¥\/ALL

GA 24 PREPAINTED G.t. r ASwiNG' 5ODmm

CA 26 G.I ROOFING SHEETS

CA 16 CEE PURLINS

Wall to roof flashing for airtight closure

CA 20 PREPAIN7ED GROOFiNG LAHCSPAN WITH IhiSULATtON UhiOERNEATH

t 2r¥jrn X 300mm FIBCR CEM. FASCIA BO DN TREATED TIMBER NAILERS

Hmm 7HK. HAROfFLEX FIBCR CEMEH7 BOARD CEILING ON h0mm X 50mm WOOD CEILIqG JOISTS aT 0.60 . O-C . (ROOF EAvE CCILING) PROyIOC A |QFIDH} SEA T ON CO/tN

Airtightness at call and roofeaves

Wall The role of walls to act as moisture barrier are detailed in the illustrations below.

Floor When it comes to moisture seepage, it is also important for floors to be treated and reinforced.

Envelope Energy Flows From an energy flow perspective, the envelope is a composition of layers with varying thermal and permeability properties. The envelope may be composed of membranes, sheets, blocks, and preassembled components. The choice of the envelope is governed by climate, culture, and available materials. The range of choices in envelope design can be illustrated by two opposite design concepts: the open frame and the closed shell. In harsh climates, the designer frequently conceives the building envelope as a closed shell and proceeds to selectively punch holes in it to make limited and special contact with the outdoors. This may also be true where there are unwanted external influences such as noise or visual clutter.

When external conditions are very close to the desired internal ones, the envelope often begins as an open structural frame, with pieces of the building skin selectively added to modify only a few outdoor forces. The flow of heat through a building envelope varies both by season (heat always flows from hot to cold and generally flows from a building in winter and to a building in summer) and by the path of the heat (through the materials of a building’s skin, or by outdoor air entering). These complexities must be considered by a designer who intends to deliver comfort and energy efficiency. Walls Understanding and optimizing the heat transfer through the walls is important in high-performance building design. Using thermal mass and insulation to your advantage with passive design strategies can help reduce the amount of energy that active systems need to use. Insulation Thermal insulation is a material that blocks or slows the flow of heat through the building envelope. Insulation is vital to most green building design because it allows spaces to retain what heat they have, while avoid gaining excess heat from outside. Total R-Values and Thermal Bridging In order to know the building's true thermal performance, you must calculate overall R-values for assemblies like walls, roofs, floors, and glazing. The total Rvalue (or "overall" R-value) of an insulated assembly may be higher or lower than the R-value of the insulation, depending on the assembly's construction. Thermal bridging is when the overall R-value is lower than the insulation's R-value.

Heat Transfer in Buildings Heat transfer takes place through walls, windows, and roofs in buildings from higher temperature to lower temperature in the following three ways: 1. Conduction: It is the transfer of heat by direct contact of particles of matter within a material or materials in physical contact. 2. Convection: It is the transfer of heat by the movement of a fluid (air or gas or liquid). 3. Radiation: It is the movement of energy/heat through space without relying on conduction through the air or by the movement of air. Heat transfer in buildings

Thermal Resistance of an Element Consisting of Homogenous Layers A building element is usually composed of a number of different materials. When materials are placed in series, their thermal resistances are added so that the same area will conduct less energy for a given temperature difference. The formation of air film at the surface of the wall or roof, due to convection movements of air, also provides resistance to the heat flow, similar to the construction material. The total resistance of the wall or roof includes all of the resistances of the individual materials that make it up as well as both the internal and external air-film resistance.

Insulation It’s important to understand Heat Energy Flows in a building to understand insulation. Insulation primarily is designed to prevent heat transfer from conduction and radiation. Resistance to conduction is measured by R-value (high thermal resistance =high Rvalue); Resistance to radiative heat transfer is measured by emissivity (high resistance =low emissivity and high reflectance). Conduction is the dominant factor when materials are touching each other; when there is an air gap between materials,

radiation becomes important. Convection usually only becomes an issue when significant air pockets are involved. Materials used for insulation fall into two broad categories: Fibrous or cellular products –These resist conductions and can be either inorganic (such as glass, rock wool, slag wool, perlite, or vermiculite) or organic (such as cotton, synthetic fibers, cork, foamed rubber, or polystyrene). Metallic or metalized organic reflective membranes - These block radiation heat transfer and must face airspace to be effective.

Insulation Materials Although insulation can be made from a variety of materials, it usually comes in five physical forms: batting, blown-in, loose-fill, rigid foam board, and reflective films. Each type is made to fit a particular part of a building.

Batting/Blankets Form Factor & Installation: In the form of batts or continuous rolls that are hand-cut or trimmed to fit. Stuffed into spaces between studs or joists. Material: Fiberglass is manufactured from sand and recycled glass, and mineral fiber ("rock wool ") is made from basaltic rock and/or recycled

material from steel mill wastes. Even recycled cotton fibers from jeans are used. Available with or without vapor and flame retarding facings. Benefits: Common and easy to install. Available in widths suited to standard spacings of wall studs, ceiling, or floor joists.

Blown-in/ Loose-Fill Form Factor & Installation: Loose fibers or fiber pellets are blown into building cavities using special pneumatic equipment. The best forms include adhesives that are co- sprayed with the fibers to avoid settling. Material: Fiberglass, rock wool, or cellulose. Cellulose is made from recycled plant material (such as newspaper) treated with fire-retardant chemicals. Benefits: Can provide additional resistance to air infiltration if the insulation is sufficiently dense.

Foamed in Place Form Factor & Installation: Roll of foil, integrated into house wrap, or integrated into rigid insulation board. These “radiant barriers” are typically located between roof rafters, floor joists, or wall studs. Material: Fabricated from aluminum foil with a variety of backings such as craft paper, plastic film, polyethylene bubbles, or cardboard.

Benefits: Resists radiative heat transfer. The resistance to heat flow depends on the heat flow direction – it is most effective in reducing downward heat flow.

Infiltration & Moisture Control Water also moves through building envelope assemblies—in both liquid and vapor states. Unwanted infiltration can be a major cause of this. The focus here is upon the water vapor movement. Water vapor will often need to be handled by a climate control system through the use of energy (termed latent heat).

Infiltration causes surprisingly large heat loss because unwanted moisture (latent heat) often must be removed from the air.

End of Discussion See attached lecture: (https://tip.instructure.com/courses/12283/files/1533315/download? wrap=1) (https://tip.instructure.com/courses/12283/files/1643022/download?wrap=1)

Reference: Philippine Green Building Code User Guide. (2016) Energy Conscious Architecture: Presentation on Building Envelope. Anant, Kiran, Riya, Sonali, Suchar, Charu. (2016) Climate Responsive Architecture. Chandan K. B. (2015)

For more references, kindly check TIP Online Resources TIP Library

(https://www.tip.edu.ph/library.html)

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END OF TODAY'S LECTURE "Sacrifice now, enjoy later." -Malabsky...