This month's head scratcher comes from Ken Tohinaka of the Vermont Energy Investment Corporation in Burlington, Vermont.

Ken explains that recently, the owners of adjacent condo units in a Vermont condominium association banded together to address energy performance and building maintenance issues. Their problems were evidenced by excessive snow melt and dangling icicles. The condo owners employed an experienced Home Performance with ENERGY STAR® contractor to develop a suitable work scope, and to perform a retrofit to solve the problem. The work scope consisted of extensive air sealing in the attic, in addition to adding another six inches of insulation. Both projects were completed successfully.

While it is too soon to determine the extent of the energy savings, the owners realize that they can still see excessive snow melt and icicles. Ken asks, "why is there still excessive heat loss?"

Think you have what it takes to Stump the Chump? Submit your stumpers to mkandel@bpi.org for a chance to be featured in BPI's Performance Matters Newsletter!

Tags: BPI, CHUMP, STUMP, THE

Views: 257

Reply to This

Replies to This Discussion

It's hard to say without seeing the building,the orientation, roof overhang and venting.
One possibility ....the microclimate near the wall is warmed by the sun...the warm air is buoyed up by surrounding cold air....warm air enters the roof thru soffit vents...and melts the snow.

note to Bud Poll...I did not say that warm air rises ;--)

The work scope does not provide enough detail.

Air sealing attic is good., but were the exterior wall top plates air sealed? That is most important juncture for ice dams.


Did the work scope include adding ventilation baffles? This is important for 2 reasons: 1) prevent thermal bridging of insulation from drywall to roof if the insulation was blown ceiling-to-deck, 2) to ensure ventilation to cool the roof deck from soffit vents.

Is there soffit ventilation? Without it, the other measures may still fall short.


How much insulation is above the top plate? Clearance issues to roof deck can leave this area with significant heat loss from ceiling to roof deck. 

If the above issues were not addressed, ice dams may still occur. For stubborn cases, I found a combination of baffles and spray foam work the best. You can get a high r-value at the low clearance soffit area and be sure that all air leakage is stopped from the top plates. This all assumes that soffit ventilation is present of course.

Interesting concept with the micro-climate by John with warm air rising from sun warmed wall - not sure how to address that, but I would try all of the above and see if the problem is solved.

Hi John and Craig,

This thread on Linkedin had an ice dam issue that was new to me and similar to your suggestion John of the wall being warmed by the sun.  Here the issue was the vent from his high efficiency boiler where the warm moist air is apparently hugging the wall and being pushed up and into the soffit above.

http://www.linkedin.com/groupAnswers?viewQuestionAndAnswers=&di...

Craig, John and I have been encouraging the energy professionals to avoid the phrase "warm air rises" to help everyone understand that warm air cannot rise by itself.  But you are forgiven if you haven't bumped into one of the many discussions :).  The issue is still debated by many.  But this is a good example of how that warm air, whether it be from a boiler vent or solar heating would be, not only pushed up, but pushed against the house where it would be directed straight into the soffit air flow.  This would not only supply heat to the bottom of the roof deck but moisture as well.

As for Ken's issue, this stumper, there are many details lacking so difficult to cover all bases.  I was waiting to see if more info would be posted.

Bud

I don't have a problem with "warm air rises", but I do have a problem with "heat rises". I just always follow up with "unless a difference in pressure is pulling it in a different direction" and explain how it can be pulled down from a hot attic if cold dense air is exiting the bottom of the building. Getting into the physics makes clients heads spin - I just want them to realize there are more forces at play. Its just easier than saying "air which is warmer than the surrounding air is pushed up by the cooler denser air exerting an upward pressure on it", which they won't understand. Really, how do you say it casually in a conversation or forum without a 20 word white paper excerpt? How about warm air increases its elevation? Sorry, I know...other threads

Could it be that the attic is connected to other units that did not receive air sealing & insulation. So the heat loss from those units still melts snow.

The inspiration for my guess comes from this Joe Lstiburek Video Starting at around 18 minutes in http://www.greenbuildingadvisor.com/roofs-video-part-2-ice-dams-lst...

course like Bud says...very few details have been provided....so only guessing

RSS

Videos

  • Add Videos
  • View All

Latest Activity

Jim Tenhundfeld posted a discussion

LED's and motion sensors

When completing an audit, a customer told me that when he installed a LED lamp in his outdoor…See More
3 hours ago
Barbara Smith posted videos
23 hours ago
CharlieK posted a discussion

Eco-Cottage Program Applauded By Housing Groups, Suppliers & Lenders

AmeriSus a leading player in the eco-kit home business kicked off a new program on MLK-day which…See More
yesterday
Diane Chojnowski posted a discussion

Call for Nominations: Tony Woods Award and Building Performance Hall of Fame

The Building Performance Institute, Inc. (BPI) is seeking nominations for the 2017 Tony Woods Award…See More
yesterday
Diane Chojnowski added a discussion to the group 1000 Home Challenge
Thumbnail

January Webinar: Intro to the 1000 Home Challenge

The January Intro to the 1000 Home Challenge webinar will be  Friday, Jan 20 at 10-11:30 AM eastern…See More
yesterday
Diane Chojnowski's event was featured
Thumbnail

Introduction to the 1000 Home Challenge Webinar at Eastern Time

January 20, 2017 from 10am to 11:30am
The January Intro to the 1000 Home Challenge webinar will be  Friday, Jan 20 at 10-11:30 AM eastern…See More
yesterday
Diane Chojnowski posted an event
Thumbnail

Introduction to the 1000 Home Challenge Webinar at Eastern Time

January 20, 2017 from 10am to 11:30am
The January Intro to the 1000 Home Challenge webinar will be  Friday, Jan 20 at 10-11:30 AM eastern…See More
yesterday
Barbara Smith's video was featured

NY State Weatherization Story

The Weatherization Assistance Program (WAP) is an energy efficiency and conservation program administered by the New York State Homes and Community Renewal (...
yesterday

Home Energy Pros

Welcome to Home Energy Pros – the unique digital community by and for those who work in the home energy performance arena.

Home Energy Pros was founded by the developers of Home Energy Saver Pro (supported by the U.S. Department of Energy) and brought to you in partnership with Home Energy magazine.  Home Energy Pros is sponsored by the Better Buildings Residential Network. Please honor our Guidelines

© 2017   Created by Lawrence Berkeley National Laboratory.   Powered by

Badges  |  Report an Issue  |  Terms of Service