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Building Envelope and Air Tightness Design
By: Kris Melag
Thermal Bridges
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Thermal Bridges are defined as a component of an object which has higher conductivity than the surrounding materials.
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Create least resistance for heat transfer
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Impact amount of energy required to heat and cool a space
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Increase rate of condensation (moisture) buildup, and thermal discomfort can become a likelihood.
"File:Aqua Tower thermal imaging.jpg." Wikimedia Commons, the free media repository. 12 Mar 2018, 00:01 UTC.
Solar Chimneys
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Improves the natural ventilation of buildings by use of convection of air heated by passive solar energy
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Vertical shafts utilizes solar energy to enhance the natural stack ventilation through a building
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Heat absorbing material is placed on the side facing the sun for maximum heat collection
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A large surface area calls for more effective heat exchange.
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Benefits include: improved ventilation rates on hot days, reduced reliance on wind driven ventilation, improved control of air flow,improved passive cooling during summer and improved thermal comfort.
Wikipedia contributors. "Solar chimney." Wikipedia, The Free Encyclopedia. Wikipedia, The Free Encyclopedia, 15 Apr. 2020. Web.
Passive Ventilation Methods
Master, Window. "3 Natural Ventilation Strategies You Should Know". Windowmaster.Com, 2020, https://www.windowmaster.com/solutions/natural-ventilation/strategies#41831. Accessed 7 Apr 2020.
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Single Sided Ventilation
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Building concept with windows on one side
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Pulse ventilation ensures quick air replacement within the room
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Benefits include lowered energy consumption, low carbon dioxide emissions, minimal maintenance, and healthy indoor environment
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Cross Ventilation
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Building concept with windows on both sides for a dual air flow concept
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Over-pressure side faces the wind while the low-pressure side is exposed to the sheltered side
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Stack Ventilation
Energy Recovery Ventilation
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Building concept similar to cross ventilation, but with window design on roof
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Fresh air enters via windows while exhausted air rises into the rooftop windows
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Energy Recovery Ventilation
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Exchanging the energy contained in humid air
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Precondition incoming outdoor fresh air in residential and commercial HVAC systems.
Week 2
Projects, Building. "Energy Recovery Ventilators In Cold Climates". Cold Climate Housing Research Center, 2020, http://cchrc.org/energy-recovery-ventilators-in-cold-climates/. Accessed 8 Apr 2020.
Advanced Framing Techniques
Helps to boost energy efficiency by insulating material and maintain structural integrity of the building. These techniques improves R value by reducing thermal bridges and maximize insulated wall area. ​
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Windows
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Materials like vinyl, wood, fiberglass, and composite frame materials provide great thermal resistance
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Double Hung Windows provide many benefits: controlled air flow, enhanced indoor air quality (cool air entry and warm air discharge), easier cleaning, adequate spacing for air conditioning, fully secure
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Casement Windows are second most efficient window design, contain air tight seals to prevent air entry and leakage, use single lever latches, provide excellent natural ventilation and lighting effects
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Low E-glass with argon gas filling using a Fibrex composite material framing will enhance energy usage
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Doors
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Choose doors with U factor of 0.00-2.00 to help prevent heat loss and include weatherstripping
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R values of steel and fiberglass clad entry doors are R-5 to R-6 rating. A 1.5" thick door without windows offer 5x the insulating value of a solid wood door.
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Patio doors with one fixed panel that swing offer tighter seal. Modern glass doors with metal frames have thermal breaks with plastic insulators
Tentative Window Choice: Energeto 8000 ED
Final Window Choice: Vinyl Casement Window
BP, Harvey. "Residential Single & Multi Unit Vinyl Replacement Casement Windows". Harvey Building Products, 2020, https://www.harveybp.com/our-products/windows/vinyl-casement-window/. Accessed 14 Apr 2020.
To the right are some casement window options that will be taken into consideration during rendering of final design
Week 3
Cincinnati Entrance Door Vinyl Entry Door Sizing: 36" x 80" x 4"
This entry door was inspired by the Cincinnati Entrance Door design. This door design includes mini square window design for solar light to enter through to provide lighting and creates great aesthetic for the residential home.
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The door handle is made of brass and the material of the door was designed using vinyl and composite plastic to prevent heat loss. In addition, the glass is triple glazed and has argon gas filling to preserve the insulation within the house.
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The hole design seen at the top of the entry door once fully fabricated is to provide natural air flow ventilation within the home. The air filtration has tiny air hole pockets to prevent harmful pollutants from entering the building atmosphere.
The roofing section design was created using Fusion 360. The material to create the roofing is Centura Steel Shingle. The roofing sections were created for the housing (left) and the garage section (right). Units are in inches.
Toward the left side bottom of the design, an overhang will be implemented over the porch to provide shading from the sun during the summer to prevent overheating of the living room.
The highlighted blue rectangle sections are to represent the placement of the solar panels that will be used to power appliances and provide heating for water used
Stud Framing
Week 4
To the right is the updated roofing section design to be made using Centura Steel Shingle design. Placement of solar panels will be on the east side near the highest room concentrated areas (e.g living room, patio). Units are in feet.
To the left is the target heating energy use. This value will be used as our limit on how much energy is consumed when heating. Given the area for roofing, wall assemblies, and windows, the target U Factor can be determined.
The ground source heat exchange system will be a closed loop (slinky coil ground source). These heat exchange systems are known to be 400% efficient, safe and clean, improve air quality, and produces no greenhouse gas emission.
Components of Wall Assemblies
1. Framed Walls
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Transfer structural loads through columns, studs, or posts​
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Include insulation and finish surfaces such as cladding panels
2. Solid Walls​
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Constructed from solid material such as masonry, concrete, brick, timber
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No cavity is included
3. Cavity Walls​
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Constructed from two skins of masonry
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Outer skin is made of brickwork, block work, or stone
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Inner skin is made of block work
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A cavity is inserted to prevent the penetration of moisture and allow for installation of thermal insulation
Roofing
To the left is a sketch to replicate which sides of the home get brick layer vs. concrete layer. One additional idea is to implement thick wood sticks as exterior material on patio side to add great aesthetic
SunTegra Solar Shingle Roofing is shown above. Goal for this building to integrate solar power within roofing material to maintain aesthetic as well as provide great energy efficiency and greater power generation output
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Solar Shingles are a new type of roofing technology designed to resemble asphalt shingles on roofs. Have same durability, flexibility, and can harness the solar energy to generate power. Each solar shingle produces 13-63 W of energy. They are lightweight, easy to install, and can withstand rain, wind, and hail. They are much more aesthetically pleasing than bulky solar panels and are 10-15% more cost effective than solar panels. The average solar panels last 20-30 years at maximum energy output. Solar shingles can produce the max energy up to 20 years. But the efficiency begins to decrease.
Week 5
This week was spent reviewing calculations for envelope sections and choosing material for advanced framing design. To view full sheet, click logo on left.
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The attached spreadsheet contains data that calculates the actual Ktot and the total Heat Energy Use Rate.
Week 6-7
Above is the envelope section calculator to determine the total heat loss and how much energy is needed to keep the home well heated and proper air flow within the home.
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PassivHaus Air Tightness Standard establishes air exchange rate has a maximum value of 0.6 air changes per hour. This building rate is set at 0.35 air changes/hr.
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To the left is calculations to determine the total Q value for the home that combines the K tot value and factors air exchange rate, air density, etc. Total energy spent was determined to be approximately 38.8 kWh.
Week 8
Above is the wall assemblies of the front and rear perspective of the building designed in AutoCADD. The visual shows on the left the insulation materials to be added to maintain air tightness such as plaster, double wood stud framing, polyurethane foam, and fiberglass. The red lines indicate the double wood stud framing implemented within the housing.
Above is the redesign for the roofing sections. The roof will be made of SunTegra solar shingles on the main building and garage. A skylight is implemented within the building to provide better lighting, especially in the concentrated areas such as living rooms, bedrooms, etc. The patio has no roofing. An overhang is placed on the living room side to ensure not too much solar heat enters.
Same version of Envelope Section Calculator with Arrows to indicate method of calculation.
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Using the U values from each material within the wall, roof, and window assemblies and multiplying by the area of the wall, roof, and window, the U values for each section was found. By adding these values up, we get the Qconduction value or Ktot in Watts/Kelvin.
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To determine Qair, values such as air density, specific heat of air, and temperature were found online. The temperature was gathered from the heating degree days modeled in Excel (done by Internal Loads lead).
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By setting the air exchange rate at 0.35 air changes per hour, this helped to calculate the air density and the air volumetric flow (Qv).
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Applying these values in a form of q = m*C*(delta T), this helps to determine the Qair in J/s. This value was converted to Watts and added with the Qcond value to get a total Qheat value of 38.8 kWh.
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