Difference between revisions of "Natural Ventilation Guidelines"

Latest revision as of 19:00, 7 September 2012

return to Sustainability Labs
return to Current Labs Summary
return to Labs Highlights

Natural Ventilation Guidelines

Goals

• Provide cooling and air movement when outside air conditions are favorable compared to indoor conditions and GG Inside Design Criteria.
• Prevent condensation from too much humidity in spaces.
• Connect people to indoor air quality and energy use.
• Provide a safe and easy way to unlock and lock windows, open upstairs back windows.

Decisions to be Made

• When can windows be open.
• When should windows be closed.
• Should ventilation and/or radiant floor cooling system also run when windows are open in open office area (hybrid operation mode).
• What are the different procedures in the enclosed offices and restrooms.
• Should all windows be closed and locked after 5 pm.

Expected Outcomes

• Energy savings from not running fans at times.
• Improved indoor air quality by fresh air and air movement in space.
• Comfortable occupants.

Guideline Development

General

• Compare indoor air conditions to outdoor air conditions relative to desired indoor design conditions and determine if windows are "enabled" to be opened if desired by occupants.
• If windows are "enabled" to be opened, indicate so to occupants so they know they can open windows, if desired. Otherwise, windows "disabled".
  • Put up a "big ass" pinwheel in the central office space to indicate that conditions are favorable for opening windows.
  • Communicate that it is not appropriate to open windows if the pinwheel is not up.
  • Include a line on the building operations opening checklist to check for NV conditions and raise or lower pinwheel.
  • Develop and communicate special policy related to opening windows in the back conference rooms.
  • If windows in these rooms are open, door to central office space should be closed so as to minimize impact on the rest of the building systems and occupants.
• Determine when windows should be closed once open and indicate to occupants.
• Determine systems mode; natural ventilation (NV) only, NV plus mechanical ventilation (low or high speed), NV plus radiant floor, NV plus mech ventil and radiant floor.

Process Measurements

• Outdoor air temperature, dewpoint, wind speed and direction.
• Forecast for GG area, short term and long term (immediate control and anticipation of where weather is heading to pre-condition building/systems).
• Indoor air temperature, humidity, dewpoint.
• Occupant perception of comfort.
• Coldest typical surface temperatures in space.

Resources Required

• NV Daily Worksheet for building daily operations
• Most reliable forecast - Intellicast
• List of measured parameters and acceptable range (max-min) where windows enabled
• Means of communicating windows enabled - Big Ass Pinwheel

Guidelines

Outdoor/Indoor Comparison

• Indoor Design Conditions: maximum 78 deg F / 60% RH (Cooling Season)
• Review daily forecast / hourly conditions predicted: temperature, dewpoint, wind speed & direction
• Use the following conditions as starting point for when windows may be opened in cooling season:
  • Dewpoint equal to or below 55 deg F
  • Outside air temperature at least 3 deg F below 78 deg F
  • Relative humidity accounted for in dewpoint parameter (changes with temperature)
  • Look at wind speed and direction in relation to temperature and dewpoint to determine how effective NV might be. May help decision making after observing and trending for a period of time. Higher wind speed that enters the building may make temps closer to indoor design more effective by creating air movement if from a direction that enters the building more readily.
• Initial conditions to use for when windows should be closed:
  • Check conditions at 10:00 a.m. and close if
    • Dewpoint greater than 55 deg F
    • Outside air temperature equal to or above 78 deg F
    • No apparent air movement from having windows open observed
  • Otherwise close windows at noon regardless of conditions

Systems Mode

• Run ERV system with wheel off to augment air movement, especially in rooms without windows or not on windward/leeward side of building.

Forecast

• Use the 10-day forecast to determine if building is generally in the heating or cooling mode. If in heating mode, may not want to open windows unless "Indian Summer" day is forecast.
• Use hourly forecast to determine when windows should be closed to hold cooling in and prevent heat from entering (in the summer time, this may be around 10:00 a.m.).

Communication

• "Big Ass" Pinwheel up when windows may be opened (Joe = Big Ass Pinwheel).
• If Pinwheel not visible, windows should be closed.

References

• Natural Ventilation Go-No Go Analysis
• NIST NV Article
• Experiment Tracker - summary of all experiments & experiment project management
• Experiment Workbook Template - report template for actual conducting of experiment

Questions

• Dirt?
• Noise?
• Wind blowing papers?
• Security?

TO DO

• Plan / Do / Study / Act / Repeat