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

Rank Order Pen/AspFrom all Minnesota Tribal Houses

Rank Order - Pen/Asp

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100.00120.00140.00160.00180.00200.00

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Main

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CR

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CE

Main

Main

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Basem

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Main

Main

Basem

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Basem

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CR

AW

L S

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Basem

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First up is moisture management

When you dig a hole and the whole fills with water you have?

A. A swimming pool

B. A well or cistern

C. Wet foundations

D. A crawl space or basement

Wet Foundations

13

Moisture Source

Moisture Source

If it is not a boat, it won’t float!

Water proofing

Basement Insulation

Basement Insulation

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.

House Wrap Proper as Specified

House Wrap Application as installed

A different approachVapor Retarder Drainage Plane

R-10 Rigid Insulation (Outperforms R-19 cavity insulation)

Drainage behind siding

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

Outside exhaust hoods (Installation)

Outside exhaust hoods (Installation)

Outside air inlets (maintenance)

When hoods get blocked . . . (maintenance)

Outside exhaust hoods (maintenance)

Outside air inlets (maintenance)

HRV (Maintenance)

HRV Filter (maintenance)

Ventilation Controls

Ventilation MaintenanceNot just for HRV’s

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

Particle Settling Velocities

Particle Size (microns) Settling Velocity

100 59.2 feet per minute

50 14.8 feet per minute

10 7.1 inches per minute

1 5.1 inches per minute

0.5 1.4 inches per hour

0.1 1.13 inches per day

<0.1 negligible

Source: AAF

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?