The Three Tiered PhilosophyComfort 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 ApproachPassive systems utilize building design to collect, store, and distribute energy

Passive vs. Active ApproachActive systems utilize mechanical means to collect, store, and distribute energy

Skin Dominate LoadingCases 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 LoadingCases 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

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 ExercisePrioritizing climate issues

Keeping The Heat In•Insulation

•Infiltration

InsulationInsulation

•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

InsulationInsulation

Law of diminishing return

A wall with:No insulation 4 inch Insulation 8 inch Insulation

U x Area x Temp. Diff.

.5 x 100 x 40 = 2000 btu/hr .076 x 100 x 40 = 304 .041 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

InsulationInsulationInstalling Insulation

•Install moisture barrier on warm side of envelop to avoid condensation inside of the wall

•Install building wrap to reduce infiltration

InsulationInsulationInstalling 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

Shading

Shadinga form generator

Shading•Must understand solar geometry

Shading•Must understand solar geometry

East / West shading problem

Shading •Fixed vs Movable shading Devices

Shading

Glazing

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 glass high SHGC .85

•Heat absorbing (tinted) moderate SHGC .60

•Reflective glass low 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 VentilationNight 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.

LightingLighting Strategy

•General lightingUse low levels of illumination for the general area

Use efficient fixture

Use affective control system

•Task lightingUse 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.

DaylightingThe Challenges:

1. Using sunlight without over heating

2. Getting light to the interior of the space

North Diffused radiation

South Direct or beam radiation

Passive Solar Heating

Passive Solar Heating

Passive Solar Heating

Passive Solar Heating

Passive Solar Heating

Passive Solar Heating

Passive Solar Heating