VENTILATION AND FENESTRATION

NATURAL VENTILATION Prior to mechanical ventilation, the high ceilings of buildings created a large volume of indoor air that diluted odors and carbon dioxide commons.wikimedia.org

NATURAL VENTILATION Air moves through a building from higher pressure areas to lower pressure areas www.downtoearth.org.in

NATURAL VENTILATION Requires: A source of air of an acceptable temperature, moisture content and cleanliness A force to move the air through the inhabited spaces of the building www.downtoearth.org.in

NATURAL VENTILATION Controls must be provided for the volume, velocity and direction of the airflow Contaminated air must be cleaned and reused or exhausted from the building www.buildinggreen.com

NATURAL VENTILATION Simplest system for getting fresh air into a building: Outdoor air for source and wind for power www.downtoearth.org.in

NATURAL VENTILATION Wind creates local areas of high pressure – windward side of a building, and low pressure on the leeward side Fresh air enters on the windward side and moves to the areas of lowest pressure www.downtoearth.org.in

NATURAL VENTILATION Window placement is critical Must have windows on at least 2 sides of the building, preferably opposite one another www.downtoearth.org.in

NATURAL VENTILATION Building should be designed to take advantage of prevailing winds – site orientation Provides for a minimum of 2 – 3 air changes per hour

CONVECTION VENTILATION Differences in the density of warmer and cooler air create the differences in pressure that moves the air Uses the principle that hot air rises – the “stack” effect www.lookfordiagnosis.com

CONVECTION VENTILATION Warm air inside a building rises and exits near the building’s top Cool air infiltrates at lower levels www.lookfordiagnosis.com

CONVECTION VENTILATION www.mognot.com

CONVECTION VENTILATION Not noticeable in buildings less than 5 stories Fire codes restrict air interaction between floors of multi-story buildings – eliminating the stack effect en.wikipedia.org

CONVECTION VENTILATION Not noticeable in buildings less than 5 stories Fire codes restrict air interaction between floors of multi-story buildings – eliminating the stack effect en.wikipedia.org

VENTILATION RATES Recommended Ventilation Rates for Offices: 20 cfm (cubic feet per minute) of outside air for each occupant 25% of amount is required to dilute carbon dioxide from human respiration 25% needed to counteract body odors Remainder dilutes emissions from indoor building materials and office equipment

VENTILATION RATES Recommended ventilation rate for offices – Slightly more than one air change per hour in an office with 8’ ceilings

VENTILATION RATES Higher rates of air replacement are needed in buildings housing heat and odor producing activities

FANS Exhaust Fans Codes prohibit discharging exhaust fans into attics, basements or crawlspaces

FANS Exhaust Fans Solar Powered Attic Fans

FANS Exhaust Fans Restrooms Must be coordinated with the ventilation system to keep odors away from other building spaces Downstream from the airflow from other spaces Air should be vented directly outside – not into other spaces

FANS Exhaust Fans Localized Exhaust Systems: Industrial process areas Laboratories Medical facilities Commercial kitchens Photocopy areas

INNOVATION Metal That Breathes http://www.ted.com/talks/doris_kim_sung_metal_that_breathes.html

FENESTRATION fen·es·tra·tion (f n -str sh n) n. 1. The design and placement of windows in a building.

FENESTRATION Fenestration of a building – windows, skylights, clerestories etc., effect heat gain and loss as well as ventilation and fenestration

FENESTRATION Proportion of glass on the exterior affects energy conservation and thermal comfort Amount of fenestration is determined by architectural considerations

FENESTRATION Window Orientation North facing windows lose radiated heat in all seasons, especially winter East facing windows gain heat rapidly in the summer South facing windows receive solar heat in all seasons West facing windows heat up rapidly in summer afternoons

FENESTRATION Windows and Natural Ventilation The open position of a window determines how well it provides natural ventilation regarding the deflection of the wind

FENESTRATION Thermal Transmission is influenced by: Window and door material Frame materials Glazing

FENESTRATION U-Value Expresses the heat flow through a constructed building section including air spaces of ¾” or more

FENESTRATION U-Value Developed by the National Fenestration Rating Council, a nonprofit collaboration of window manufacturers, government agencies, and building trade associations

FENESTRATION U-Value Measures whole window conditions Measures how well product prevents heat from escaping a building

FENESTRATION U-Value General ratings – between .20 and 1.20 Smaller ratings = less heat escaping

FENESTRATION Solar Heat Gain Coefficient SHGC Provided by the NFRC

FENESTRATION Solar Heat Gain Coefficient Measures how much of the sun’s heat will pass through to the interior Ratings 0 – 1.0 Higher rating = more heat passing through

FENESTRATION Solar Heat Gain Coefficient

FENESTRATION Glazing Materials Materials should be appropriate for the amount of light that needs to pass through Thermal performance and life cycle costs are important economical considerations

FENESTRATION Glazing Materials Color is important for certain applications such as artist studios, showrooms and retail spaces