Presentation on theme: "The Three Tiered Philosophy Comfort by mechanical means Meeting comfort needs passively rather than relying on power grid Daylighting Ventilation Passive."— Presentation transcript:
The Three Tiered Philosophy Comfort by mechanical means Meeting comfort needs passively rather than relying on power grid Daylighting Ventilation Passive solar heating Mass cooling Lower the need for energy through building design
Passive vs. Active Approach Passive systems utilize building design to collect, store, and distribute energy
Passive vs. Active Approach Active systems utilize mechanical means to collect, store, and distribute energy
Skin Dominate Loading Cases where the dominate heat gain / loss are climate driven and the skin design is critical. Dominate loads Insulation Glass Mass & color of skin infiltration
Internal Dominate Loading Cases where the dominate heat gain is driven by internal conditions. Dominate loads Lighting Occupants Equipment Core space not affected by outside conditions
Insulation Infiltration Control Shading Glazing Ventilation Lighting Lighting Controls Day Lighting Evaporative Cooling Thermal Mass Surface condition Passive Solar Heating High Efficiency HVAC Economizer Cycle Exhaust Air Energy Recovery HVAC Controls Basic Design Strategies
Too hot for comfort Skin Dominate Loading Internal Dominate Loading Too cold for comfort Skin Dominate Loading Internal Dominate Loading Sub-divide strategies as indicated
Basic Design Strategies Too hot for comfort Skin Dominate Loading 1.Avoid the sun 2.Natural ventilation 3.Surface conditions
Basic Design Strategies Too cold for comfort Skin Dominate Loading 1.Keep the heat in 2.Passive solar heating 3.Compact design reduce skin surface area
Basic Design Strategies Don’t assume a strategy is right for every building A nightclub will not benefit from daylighting Buildings located along the expressway may not want natural ventilation Evaporative cooling is not effective in the south Shading is not important in areas dominated by overcast skies Strategies should be project specific
Lighting Lighting Controls Day Lighting Exhaust air energy recovery Basic Design Strategies Internal Dominate Load Building
Class Exercise Prioritizing climate issues
Keeping The Heat In Insulation Infiltration
Insulation Meet energy code requirements for R-value Three basic forms Rigid foam – serious fire hazard Blown-in-place - blown around attic Fiberglass blankets – must remain dry
Insulation Law of diminishing return A wall with: No insulation4 inch Insulation 8 inch Insulation U x Area x Temp. Diff..5 x 100 x 40 = 2000 btu/hr.076 x 100 x 40 = x 100 x 40 = 164 reduction of 1700 btu/h reduction of 140 btu/h Blocking air leaks is more effective than increasing R value
Insulation Installing Insulation Install moisture barrier on warm side of envelop to avoid condensation inside of the wall Install building wrap to reduce infiltration
Insulation Installing Insulation
Infiltration Control Infiltration increases with air velocity Develop wind buffers Trees / land mass / other buildings Use windows and doors with better weather stripping Install building wrap Use sealants
a form generator
Shading Must understand solar geometry
Shading Must understand solar geometry East / West shading problem
Shading Fixed vs Movable shading Devices
Glazing for Hot Climate Concept - spectrally selective glazing Transmits one portion of solar energy and block another
Glazing Understand solar geometry
Glazing Glazing properties U value – pertains only to conduction – has not affect on direct radiation SHGC – percentage of solar energy allowed through the glass Glazing options Clear single pane high SHGC.90 Clear insulated glasshigh SHGC.85 Heat absorbing (tinted) moderate SHGC.60 Reflective glasslow SHGC.35
clear Heat absorbing Reflective
Natural Ventilation Cross ventilation Controls humidity buildup Enhances evaporative cooling Introduces fresh air Provide openings on opposite sides of the building. Strategy depends on natural breeze to work. Outside air quality may limit the use of natural breezes. Design enhancements to increase affect.
Natural Ventilation Stack ventilation Concept is based on thermal convection and therefore does not require a natural breeze. Works best in spaces with high ceilings that provide high louvers for heat escape and low louvers for incoming cool air.
Natural Ventilation Night Flushing Concept is based on the heat capacity of the buildings mass. The building mass absorbs heat throughout the day. Cool night air is circulated through the building to cool the mass. By morning, the cycle is ready to start over. Concept relies on cool nigh air. It is not effective when night temperatures remain relatively high.
Lighting Lighting Strategy General lighting Use low levels of illumination for the general area Use efficient fixture Use affective control system Task lighting Use higher levels of illumination at work stations The combined strategies results in a much lower watts / sf. figure.
Daylighting a form generator
Daylighting Solar simulation is the best way to evaluate shading strategies. Photo documentation can be made for each hour of the day for any day of the year.
Daylighting South facing glass must: limit the quantity of light to avoid over heating. Avoid direct beam radiation reaching the building interior. Diffuse the light.
Daylighting The Challenges: 1.Using sunlight without over heating 2.Getting light to the interior of the space North Diffused radiation South Direct or beam radiation