460 likes | 610 Views
National Tribal Forum on Air Quality. Co-Sponsored by: Institute for Tribal Environmental Professionals & National Tribal Air Association. New Construction Methods & Mold Prevention. Steve Klossner. New Construction Methods & Mold Prevention. What are we building? Healthy/Durable/Efficient
E N D
National Tribal Forum on Air Quality Co-Sponsored by: Institute for Tribal Environmental Professionals & National Tribal Air Association
New Construction Methods & Mold Prevention Steve Klossner
New Construction Methods & Mold Prevention • What are we building? • Healthy/Durable/Efficient • Useful life of our buildings • Moisture management • Maintenance requirements and responsibilities • First costs driven construction methods • No performance requirements
Oversight requirements • Innovative and durable design takes additional resources during construction • From the design team • From the builder • From all subcontractors • From the building owners • A process for making sound decisions on site
Wall cavity insulation • Why do we insulate wall cavities? • What happened when we added insulation?
Winter relative humidity • Can be maintained with flow thru humidifier • MUST HAVE OUTSIDE RESET • Current practice (fear of winter RH) generally precludes these from being installed
Summer relative humidity • Can only be controlled with air conditioning system or dehumidification • Dehumidifiers cost as much as air conditioning to operate • Dehumidifiers add heat to the home • Most basements and crawl spaces are at or below the dew point for the RH in summer • Guarantees mold growth
First up is moisture management • When you dig a hole and the whole fills with water you have? • A swimming pool • A well or cistern • Wet foundations • A crawl space or basement
Above Grade Construction Considerations • Are we building our houses too tight? • Are we putting too much insulation in our walls and ceilings? • Are our air handlers tight enough to not generate interstitial pressure problems?
Air Flow Management • Unfiltered air leaking through a typical 2,000 square foot house due to wind, stack effect, leaky ducts, and unbalanced air distribution systems. • 900 CFM during very cold windy weather. • 300 CFM average during the year. • 30 CFM during mild weather and low wind.
Heat and Energy Recovery Ventilation • With high fuel costs would seem appropriate • Energy recovery rates from 60-90% • Increases the temperature of inlet air • Significant for occupant comfort • Has significant maintenance requirements • Or becomes exhaust only or worse no ventilation
So for ventilation. . . • Simple is best • HRV’s only if we are willing and able to complete maintenance requirements • Monthly for filters • Quarterly for air inlets • Bi-yearly for core • ERV’s with above maintenance AND • Capillary breaks • Water proofing
Filtration • Primarily for IAQ we need to be concerned with smaller particles • Most low cost furnace filters will not capture these • MERV rating of 10 or greater is appropriate for IAQ • To filter the air, the air handler has to be in operation • Same requirements as ventilation distribution
Source:AAF Particle Settling Velocities
Filtration & Air Handler Operation • Care must be taken when choosing high efficient filtration • 1” filters tend to have high static pressure • Number 1 cause of compressor failure • Will cause short cycling in heating season (efficiency) • Maintenance requirements for 1” filter are higher • Four inch filter with pressure sensor is the sliced bread of residential filtration
How to Move Forward • Measurable, quantifiable, specifications seems to be one of the ways we should be moving. • Interior relative humidity • Shell tightness (whole building) • Ventilation • Measured flows • Distribution • Operating costs and system efficiencies • Maintenance issues and costs
Closing Thoughts • We need to spend more time evaluating what works and what does not work in housing ($) • If we understand what is “broke”, we can fix it and design it out of the next project. • If we don’t we will simply perpetuate the problem or spend monies on inappropriate fixes • The solutions are out there, we simply need to find and adopt them!
Thanks! • Questions or Discussions?