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Designing with Nature

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Title: Slide 1 Author: Administrator Last modified by: Robert Fehr Created Date: 8/12/2008 7:43:48 PM Document presentation format: On-screen Show (4:3) – PowerPoint PPT presentation

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Title: Designing with Nature


1
Designing with Nature
2
The Importance of Climate-Appropriate Design
3
Climate-Appropriate Design
  • Climate Zones
  • For energy code compliance, North America is
    separated into 7 climate zones, each with special
    recommendations for
  • 1. insulation levels and ventilation
  • 2. configurations of crawlspaces and attics
  • 3. foundation types.

www1.eere.energy.gov/buildings/residential/climate
_zones.html
4
Cold and Very Cold Climate Zone
  • Zones 5, 6 7
  • Cold and very cold climates present several
    challenges for home building.
  • In the cold and very cold climates, houses must
    be nimble in response to changing temperature and
    moisture conditions.

5
Hot-Dry and Mixed-Dry Climate Zone
  • Zones 2 3
  • The intense solar radiation imposes a large
    thermal load on houses that can increase cooling
    costs, affect comfort, and damage home
    furnishings.

6
Hot and Humid Climate Zone
  • Zone 1
  • Hot and humid climates present some of the
    same challenges for home building as in the
    Hot-Dry zones.
  • High humidity and high rainfall is significant
    problem.
  • Significant levels of moisture most of the year.
  • Air-conditioning is installed in most new homes,
    cold surfaces are present and condensation can
    occur.
  • Controlling the infiltration of moisture-laden
    air are major goals of design and construction in
    this climate zone.

7
Marine Climate Zone
  • Zones 3 4 Marine
  • The marine climate covers a narrow band from
    the Canadian border south to the county boundary
    separating Ventura and Los Angeles California.
  • The marine climate was designated in
    recognition of the mild temperatures and moist
    conditions found along the coast.

8
Mixed-Humid Climate Zone
  • Zone 4
  • Homes in the mixed-humid climate are faced
    with a substantial heating season with monthly
    average temperatures dropping below 45ºF.
  • The summers can have soaring humidity.

9
Mixed Climate Best Practices (Zone 4)
  • Homes in mixed-humid climates are faced with a
    significant heating season as well as a cooling
    season with significant latent load.
  • 1. Reducing solar gain.
  • 2. Correct sizing of air conditioning
    systems is important in the control of interior
    humidity.
  • 3. Over sizing air conditioning systems in
    this climate typically leads to moisture problems.

www.buildingscienceconsulting.com/designsthatwork/
mixedhumid/bestpractices.htm
10
Building Design, Systems Engineering, and
Commissioning for Mixed Climates
  • Design for Energy Performance
  • Energy performance 40 better than the 1995
    Model Energy Code
  • (Base house i.e. equal to 10 better than Energy
    Star performance requirements).

www.buildingscienceconsulting.com/designsthatwork/
mixedhumid/bestpractices.htm
11
Systems Engineering (Mixed Climates)
  • Design structure using advanced framing methods.
  • Design structure to accommodate duct distribution
    system placing all ducts and air handling
    equipment within conditioned space.
  • Design and detail structure for durability, wall
    and roof assembly drying potential, continuous
    drainage plane, and continuous thermal barriers
    that clearly defines the conditioned space.

www.buildingscienceconsulting.com/designsthatwork/
mixedhumid/bestpractices.htm
12
Commissioning - Performance Testing (Mixed
Climates)
  • Air Leakage
  • Blower door depressurization
    testing
  • Less than 2.5 square inches/100 square feet
    surface area leakage ratio

  • OR
  • 0.25 CFM/square foot of building enclosure
    surface area at a 50 Pa air pressure
    differential.

www.buildingscienceconsulting.com/designsthatwork/
mixedhumid/bestpractices.htm
13
Commissioning - Performance Testing (Mixed
Climates)
  • Duct Leakage
  • Ducts distributing conditioned air, should be
    limited to 5.0 percent of the total air handling
    system rated air flow at high speed.
  • (Nominal 400 CFM per ton) determined by
    pressurization testing at 25 Pa.

www.buildingscienceconsulting.com/designsthatwork/
mixedhumid/bestpractices.htm
14
Commissioning - Performance Testing (Mixed
Climates)
  • Forced air systems should be designed to supply
    airflow to all conditioned spaces and zones
    (bedrooms, hallways, basements) and provide a
    return path from all conditioned spaces or zones.
  • Inter-zonal air pressure differences, when doors
    are closed, should be limited to 3 Pa.
  • Mechanical ventilation system airflow should be
    tested during commissioning of the building.

www.buildingscienceconsulting.com/designsthatwork/
mixedhumid/bestpractices.htm
15
Site - Drainage, Pest Control, and Landscaping
(Mixed Climates)
  • Drainage
  • Site grading and landscaping should be planned
    for building run-off.
  • Roof drainage directed at least 3 feet beyond the
    building, surface grade of at least 5
    maintained for at least 10 feet around and away
    from the entire structure.

www.buildingscienceconsulting.com/designsthatwork/
mixedhumid/bestpractices.htm
16
Site - Drainage, Pest Control, and Landscaping
(Mixed Climates)
  • Pest Control
  • Based on local code and Termite Infestation
    Probability (TIP) maps.
  • Use environmentally-appropriate termite
    treatments, bait systems, and treated building
    materials that are near or have ground contact
    http//www.uky.edu/Agriculture/Entomology/entfacts
    .htm

www.buildingscienceconsulting.com/designsthatwork/
mixedhumid/bestpractices.htm
17
Site - Drainage, Pest Control, and Landscaping
(Mixed Climates)
  • Landscaping
  • Plantings should be held back 18 inches from the
    finished structure.
  • Supporting irrigation directed away from the
    finished structure.
  • Decorative ground cover - mulch or pea gravel, no
    more than 2 in depth for the first 18.

www.buildingscienceconsulting.com/designsthatwork/
mixedhumid/bestpractices.htm
18
Foundation - Moisture Control (Mixed Climates)
  • Foundation Moisture Control
  • The building foundation shall be designed and
    constructed to prevent the entry of moisture and
    other soil gases.
  • Sub-slab drainage shall consist of a granular
    capillary break directly beneath the slab vapor
    retarder.
  • Use radon resistant construction practices.

www.buildingscienceconsulting.com/designsthatwork/
mixedhumid/bestpractices.htm
19
Foundation - Energy Performance (Mixed Climates)
  • Energy Performance
  • - Slabs at the perimeter.
  • - Consider the use of borate-treated rigid
    insulation on the slab perimeter.

www.buildingscienceconsulting.com/designsthatwork/
mixedhumid/bestpractices.htm
20
Envelope - Moisture Control (Mixed Climate)
  • Moisture Control  
  • Water management - Roof and wall assemblies
    must provide drainage in a continuous manner over
    the entire surface area of the building
    enclosure.
  • Vapor management - Roof and wall assemblies must
    contain elements that, individually and in
    combination, permit drying of interstitial
    spaces. No plastic sheeting in walls.
  •  

www.buildingscienceconsulting.com/designsthatwork/
mixedhumid/bestpractices.htm
21
Envelope Energy Performance (Mixed Climate)
  • Energy Performance 
  • Air leakage
  • Exterior air flow retarder - foam sheathing
  • Interior air flow retarder - gypsum board sealed
    at frameing.
  • Windows   1. U-factor 0.35 or lower and SHGC
    (solar heat gain coefficient) 0.35 or less,
    regardless of climate.   2. Climate-specific
    glazing properties if passive solar orientation
    and design can be employed by the builder and
    occupants employ proper window treatments and
    their use.

www.buildingscienceconsulting.com/designsthatwork/
mixedhumid/bestpractices.htm
22
Mechanicals / Electrical / Plumbing (Mixed
Climate)
  • HVAC Systems Engineering
  •  HVAC system design, both equipment and duct,
    should be done as an integral part of the
    architectural design process.  
  • HVAC system sizing should follow ACCA Manual J
    and duct sizing should follow Manual D  
  • Mechanical ventilation should be an integral part
    of the
  • HVAC system design

23
Mechanicals / Electrical / Plumbing (Mixed
Climate)
  • Energy Performance
  • Air conditioner / heat pump shall be installed
    according to best practices.  
  • Major appliances meet high-energy efficiency
    standards using current appliance ratings.

24
Mechanicals / Electrical / Plumbing (Mixed
Climate)
  • Occupant Health and Safety
  • Best Practice
  • Base Ventilation Controlled mechanical
    ventilation minimum of 15 CFM per master bedroom
    and 7.5 CFM for each additional bedroom (when the
    building is occupied.)  
    -Zones Inside the Home-
  • Intermittent Spot Ventilation 100 CFM for each
    kitchen, range hoods must be vented to the
    outside (no re-circulating hoods). Intermittent
    spot ventilation of 50 CFM, or continuous
    ventilation of 20 CFM when the building is
    occupied should be provided for each
    washroom/bathroom.

25
Occupant Health and Safety cont..
  • Occupant Health and Safety
  • All combustion appliances in the conditioned
    space must be sealed combustion or power
    vented.
  • Designs that incorporate passive combustion air
    supply openings or outdoor supply air ducts not
    directly connected to the appliance should be
    avoided.
  • Provide filtration systems for forced air systems
    that provide a minimum atmospheric dust spot
    efficiency of 30 or MERV of 6 or higher.
  • Indoor humidity should be maintained in the range
    of 25 to 60 by controlled mechanical
    ventilation, mechanical cooling, or
    dehumidification.

26
Occupant Health and Safety cont..
  • Occupant Health and Safety
  • Carbon monoxide detectors (hard-wired units)
  • one per every approximate 1000 square feet)
    in any house with combustion appliances and/or an
    attached garage.
  • Information relating to the safe, healthy,
    comfortable operation and maintenance of the home
    and systems provided to homeowner.  

27
Envelope/Mechanicals Management (Mixed Climate)
  • Envelope/Mechanicals Management
  • Plumbing - No plumbing in exterior walls.
  • Air seals (caulking etc.) around plumbing
    penetrations in rim (band) joist or ceiling. 
  • Electrical - Seals around wires penetrating air
    barrier or pressure boundary.

28
Other Climate Design Criteria
  • Seismic Zone
  • Basic Wind Speed
  • Soil bearing
  • Snow load
  • Frost line
  • Flood zones
  • Fire hazard zones
  • Water accessibility

US seismic zones
29
Climate Induced Design Examples
  • VERY Cold and Windy

30
Climate Induced Design Examples
  • Local materials
  • Natural
  • ventilation

31
Climate Induced Design Examples
  • Material availability

32
Climate Induced Design Examples
  • Hot and dry climate

33
Climate Induced Design Examples
  • Limited space

34
What is Passive Solar Design?
  • Passive solar design strategies
  • Building orientation and room layout
  • Thermal mass design
  • Insulation, air sealing, duct sealing details
  • High efficiency HVAC
  • Window design and placement
  • Window efficiency characteristics
  • Overhang height and width

35
Thermal Mass Sizing
  • Specific heat
  • Concrete 0.20 Btu/ degree-pound
  • Water 1 Btu/ degree-pound
  • Concrete -- 3 to 6 square feet of 4 to 6 thick
    concrete per square foot of South-facing glass (1
    cu ft of mass per sq ft of glass)
  • Water ½ cubic foot per square foot of glass
    (about 4 gallons)
  • Thinner mass works better in eastern U.S.
    cloudier winters

36
Select an appropriate mass color
Dark
Medium
Light
No Covering
Vinyl
Carpet
37
Indirect Gain (Trombe Walls)
  • Using a Trombe wall is the most common
    indirect-gain approach.

38
Solar Geometry, Fenestration, Natural Ventilation
39
Solar Pathfinder
40
Sun Chart for 34 degrees N. Latitude
41
Building Geometry Related to the Local
Environment
42
Overhang Design
Climate Zone 4 1 of overhang 3.8 of shading
for the summer
43
-Overhang Design- The average temperature for a
given day is 55F (NOAA) Since this value is ten
degrees lower than the reference point of 65F
then one would say this is a ten degree-day.
Overhang Design cont
  • Moderate climates- below 6,000
  • Heating Degree Days (HDD) Base 65F 18C)
    and below 2,600 cooling degree days (CDD) (at
    base 75F 22C)
  • Locate shadow line at window sill using the June
    21 (summer solstice) sun angle.

44
Typical Climate Values--Zone 4
45
Other Shading Options
46
Natural Cooling
  • Dehumidification and moisture control
  • Overhangs on south side
  • Tree shading, solar screens on east and west
  • Vegetation around house to reduce ground
    reflected sunlight
  • Interior fans for air movement

47
Natural Cooling
48
What is a Fenestration?
  • Products that fill openings in a building
    envelope, such as windows, doors, skylights,
    curtain walls, etc., designed to permit the
    passage of air, light, vehicles, or people.

49
Sun Tubes
50
Low E Windows
51
Low-E Windows cont
  • Low-emissivity (Low-E) coatings are
    microscopically thin, virtually invisible, metal
    or metallic oxide layers deposited on a window or
    skylight glazing surface primarily to reduce the
    U-Factor by suppressing radiant heat flow.

52
Window U-Factor
  • The U-factor measures how well a product prevents
    heat from escaping. The rate of heat loss is
    indicated in terms of the U-factor of a window
    assembly. U-factor ratings generally fall between
    0.20 and 1.20.
  • The insulating value is indicated by the R-value,
    which is the inverse of the U-factor. The lower
    the U-factor, the greater a window's resistance
    to heat flow and the better its insulating value.

53
Solar Heat Gain Coefficient
  • The Solar Heat Gain Coefficient (SHGC) measures
    how well a window blocks heat from sunlight. The
    SHGC is the fraction of the heat from the sun
    that enters through a window. SHGC is expressed
    as a number between 0 and 1. The lower a window's
    SHGC, the less solar heat it transmits.

54
Estimating Passive Solar Savings
  • The following approximates the annual heating
    energy savings of passive solar homes
  • Each square foot of double-glazed south- facing
    window that is un-shaded in the winter will save
    40,000 to 60,000 Btu per year on a homes heating
    bill, if sufficient thermal mass exists.
  • Low-emissivity glass will increase the savings 15
    to 30 percent.
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