ASHRAE Journal - August 2013 - 51

Technical FeaT
FeaTure

more energy efficient than ventilation. Does ventilation
still help to improve performance when the outdoor air
is highly polluted? Does the data showing better performance in schoolwork tasks and improved scores in standardized academic performance tests when classrooms
have higher outdoor air ventilation rates really indicate
better learning by students? We know that sick building syndrome symptoms in offices diminish with more
outdoor air ventilation—does the reduction in symptoms
increase our work performance?
Answering these and other important questions are
keys to production of buildings that maximize performance and learning. In addition, future research should
more often assess the relationships of indoor environmental parameters to high level cognitive performance,
such as decision making performance, and rely less on
task performance, such as typing speed or proof reading
accuracy.
Although the list of important unanswered questions
is long, the existing findings are more than sufficient to
motivate actions to improve aspects of indoor environmental quality. Economic analysis show that the economic benefits of measures that improve performance
and decrease absence will far outweigh the implementation costs. However, is imperative that we consider how
our actions, designed to improve productivity and learning, affect building energy use and emission rates of
greenhouse gases. We are challenged to provide healthy
and productive indoor environments while making our
buildings even more energy efficient. The challenge is
large, but the challenge is one we must meet.
William J. Fisk is senior scientist and leads the Indoor Environment Group, Lawrence Berkeley National
Laboratory, Berkeley, Calif.

Filtration and Air Cleaning
Where are We and Where are We Going Next?
By H.E. BarNEy BurrouGHs, PrEsIdENtIaL MEMBEr/FELLoW asHraE

Tight Building Envelopes—Finally
By aNdrEW PErsILy, PH.d., FELLoW asHraE

Sometimes the next best idea has been around
for a quite a while. That is the case with building
envelope airtightness, the importance of which
was recognized in the 1960s by researchers and
practitioners in Canada who learned the hard way
that a leaky building had a host of problems. Since
then the learning curve of the advantages of building tightness has been a slow one, but we are finally
getting to the point where more and more people in
the building community have learned the important of airtightness. To summarize, infiltration is a
bad way to ventilate a building; its rate and distribution is uncontrolled and unreliable, the incoming air is unfiltered, and it can have serious negative impacts on thermal comfort, indoor air quality
and material durability. Oh yeah, and it consumes
unnecessary energy 24-7.
So, what’s new and where are we going. In recent
years we have seen air barrier requirements added
to ASHRAE Standards 90.1 and 189.1, as well as
a number of state and federal construction programs. Training and awareness have also increased,
helping designers and contractors to build tight.
But there is more work to be done.
Only some of these standards and programs
require actual airtightness testing, which is the
only way to know the building is actually achieving
its performance goals. Good intentions and applying air sealing membranes or sealants do not alone
make a building tight. It takes attention to details,
particularly intersections between different wall
types, windows and roofs, to get the job done. If
we are going to achieve the decades old mantra of
“build tight, ventilate right,” we need to continue
to get serious about airtightness by continuing to
increase awareness and training, and by measuring
the airtightness of our building as a routine part of
the construction process.

Filtration and air cleaning (FAC) is a relatively mature
environmental technology that has a great deal of
remaining stamina and potential. But to understand its
significance in the future, it is important to appreciate
andrew Persily is leader, supervisory Mechanical Engineer, Energy and Environment division,
the progress made over recent decades that will set the
Indoor air Quality and Ventilation Group, National Institute of standards and technology.
stage for a launching pad into the future.
When I entered the industry, the HEPA filter (created
in nuclear, pharmaceutical, and electronics facilities.
in World War II as part of the Manhattan Project) was
The self-supporting, extended high-efficiency pocket
being manufactured under patents and only was applied filter had just been invented and patented and was
Au g ust 2013

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