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Stellar Apartments PASSIVE HOUSE

As one of the largest providers of low-income housing in Lane County, St. Vincent de Paul Society of Lane County (SVdP) strives to provide high quality, affordable rental housing to its low-income residents.  Energy efficiency, and the resulting lower energy costs for residents, is a key component of both quality and affordability.   All of SVdP's new housing is constructed and certified to EWEB's Earth Advantage Program.  The Earth Advantage Program employs a variety of features and techniques to save at least 15% more energy compared to a home built to code while also enhancing indoor air quality and durability.   But SVdP wants to move beyond the higher energy efficiency provided by standard construction methods.   So at Stellar Apartments, they decided to test out a new construction technique - the Passive House Standard - that uses fairly common materials to raise the bar on envelope design to a whole new level. 

The Passive House Standard is way of construction that focuses on creating "energy efficient buildings with year-round comfort and good environmental conditions."  (Passive Home Guidelines)  By constructing a building to this standard - highly insulated and extremely air tight envelope, triple pane glazing, efficient domestic water heating, and incorporation of an energy-recovery mechanical ventilation system (ERV) to preheat or cool incoming fresh air - the heating and cooling needs are minimized. The result is a highly energy efficient building with very low utility costs and a high level of comfort and indoor air quality.

In addition to St. Vincent de Paul's interest in moving beyond the Earth Advantage Program, both EWEB and the City of Eugene are interested in the potential of the Passive House Standard for lowering energy usage and as a new standard to promote greater energy efficiency for single and multi-family housing in the area. The community vision for testing the Stellar Passive House was to build two identical buildings - one to Passive House Standard and one to Earth Advantage Certification - and compare the resulting energy use and environmental qualities of each, within the context of the additional construction cost of Passive House.  The Stellar Apartments Passive House Building and the Earth Advantage Building have identical floor plans and volumes.  Both have 6 units - (2) two-bedroom units on the ground floor, and (4) two-bedroom townhouses above. Both buildings are oriented in the same direction in the same area of the site, with similar shading conditions. The primary differences between the two buildings are the levels of insulation, air tightness, and the use of the mechanical ERV.

A team of graduate students under the direction of Professor Alison Kwok at the University of Oregon will be evaluating the energy use and indoor environmental quality (IEQ) of each building over a two-year period. Specific areas to be examined include thermal comfort, lighting quality, energy use and energy savings, indoor air quality benefits, and perhaps the level of acoustic comfort. At the end of the two-year period, the University of Oregon study will give St. Vincent de Paul, EWEB, and the City of Eugene, as well as other housing providers, the opportunity to compare the resultant differences of each building type and determine the value of promoting the Passive House Standard in future housing projects and programs.

The University of Oregon study will make comparisons between the Passive House building and the Earth Advantage building based on findings in each of the following topic areas.

Energy Use and Cost Savings:

  • What is the total energy use of each building by month/annually?
  • Does the Passive House energy use reduction meet the 90% claim?
  • What are the heavy energy using appliances in the plug load category? Do plug loads change by season?
Air Quality (CO2, particulate, VOCs):
  • Do carbon dioxide levels in the house meet acceptable recommended levels?
  • How do carbon dioxide levels change with the ERV operation? With cooking? With window operation?
  • What are the levels of particulate in the air (indoor/outdoor)?
Temperature and Comfort:
  • Does the Passive House maintain an average indoor temperature of 68 degrees Fahrenheit during the heating period?
  • Are the temperature swings present in the space less than the 4  degrees above or below 68 degrees Fahrenheit specified by the Passive House Standard?
  • What is the temperature of the window wall compared to the ambient room temperature?
  • What are comfort levels? If there are any areas of discomfort, what causes them? How does it compare to physical thermal conditions to the comfort range setup by ASHRAE?
Light Quality:
  • What are the patterns of illuminance in the main living space during the winter? During the summer?
  • Are the illuminance levels within acceptable lighting standards for reading tasks? (IES)
  • Does the main living space have areas with potential glare? What do the occupants say?
  • Do luminance ratios change with season?
Acoustics:
  • Do the sound levels within the space meet the 24DBa levels set by the EPA?
  • Are occupants more sensitive to sound within the space?
  • What types of sounds do they notice? What are the sources?
  • Do occupants find the acoustics in the space pleasing?
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