Doing the
Right Thing, Part Four
In closing last time I wrote about LEED-NC’s
concern with minimum energy performance, but what was left
unstated was the fact that its primary reliance is on computer
modeling of the energy consumption of the proposed
building. This
primary method awards from 1 to 10 points, dependent upon the
percentage improvement when compared to the ASHRAE Standard’s
baseline building performance. LEED-NC also recognizes an alternate prescriptive
compliance path which awards only 4 points, for office
buildings up to 20,000 square feet in size, and finally
recognizes a third alternate awarding only one point for
partial prescriptive compliance of any type building of any
size.
Computer modeling of energy consumption,
while rather involved (to the point of adding $50K in
consulting fees to a reasonably large commercial building)
should revolve around the proposed use of such energy
efficient systems so as to pay back both the differential cost
of the equipment and the extra fees within 2 to 5 years, and
this has actually been happening more and more of late.
The next metric in the Energy and Atmosphere
rating area is Renewable Energy, with LEED-NC awarding from 1
to 3 points dependent upon what percentage of the building’s
energy comes from on-site renewable sources. LEED-EB awards up
to 4 points and allows for purchase of green power from
off-site energy sources, with these differences again
reflecting the relatively greater difficulty in trying to make
an existing building energy efficient. In both LEED-NC and
LEED-EB, however, while the guidance refers to non-polluting
sources, it also allows for biomass and biogas sources; i.e.,
combustion, which must result in the formation of
CO2, which, since
it’s used by green plants, is not so bad as the carbon
monoxide and oxides of nitrogen resulting from the incomplete
combustion in pre-EPA automobiles and
industry.
This reflects the reality that, wind, solar, and
geothermal sources are neither sufficiently widespread nor
sufficiently high in specific power capacity to supply power
to commercial or industrial users. You have to burn
something, or go to nuclear power, or decide modern technological society is a net negative, and
turn away from it if you expect to get energy only from sun, wind, or geothermal
sources.
Green Building methods exist because modern technological society has in fact
been a net positive, and the idea is to do what one can to
keep it that way. LEED-NC reinforces this via the awarding of
one additional point for off-site green power, separate from
the 3 on-site renewable power points. LEED-NC closes out this
rating area with one point each for enhanced commissioning,
enhanced refrigerant management, and measurement and
verification of energy consumption over time, which completes
the 17 points of a “perfect” score in the LEED-NC Energy and
Atmosphere rating area.
All of the difference, and more, between
that score and the 23 points of a “perfect” LEED-EB score in
the Energy and Atmosphere rating area is comprised by a
building operation and maintenance metric worth up to 3
points, and a performance measurement metric worth up to 4
points.
This makes all the sense in the world. If there’s one area in
which things seem to go downhill at lightspeed, it’s in the
actual operation and maintenance of a building‘s mechanical
systems. The three operations and
maintenance points are awarded as one point for staff
education (24 hours per person per year), one point for
systems maintenance, and one point for systems
monitoring.
While the one point for monitoring is awarded for simple
alarming to indicate out of spec conditions, the performance
measurement metric awards 3 of its 4 points for continuous
data gathering at the rate of one point per 4 data items, from
a list of 14 such items. You don’t get the points for just measuring and
reporting, however. You have to use the data in a performance
improvement program, providing a quarterly report card of each
item metered.
This brings us to the last
LEED-EB performance measurement point, which is awarded for a
measured 10% reduction in environmental
emissions.
The next rating area, Materials and Resources,
because it has to do with the components of construction
materials, construction and operational waste
products, and, in the case of LEED-EB, the use of non-toxic
biodegradable cleaning products, particularly lends itself to
negotiated contract and design-build projects, which, by
definition, have a construction team on board while still in
the design process.
The next to last rating category, Indoor
Environmental Quality (22 points EB, 15 points NC), is what
very often is the deciding factor in convincing a building
owner-occupant to go after LEED certification.
Green Building seminar lately,
you’ve heard over and over again how the largest part of a
building’s operating cost is the salary and benefits paid to
the people who work there.
Simple math shows that small increases in
employee productivity and retention have a huge effect on the
operating cost of a building, with one case purporting to have
generated enough savings to have paid for the entire project (not just the
premium for sustainable design and construction) in two
years.
The particulars of this rating area have to do
with lighting, thermal comfort control, and removal of indoor
pollutants, which leads to one of the “gotchas” of sustainable
design. Indoor
pollutant removal is effected by outdoor air being injected
into the building’s HVAC system, and the NYS Energy
Conservation Construction Code in some cases calls for more
outside air than is presently called for in New York City’s Building Code. A
similar situation exists vis-à-vis the NYC Building Code,
ASHRAE 90.1, and LEED.
Oops.
That is, the cooling and dehumidification of
summertime outside air is a very large part of
the air conditioning load, is rather more difficult and costly
than mitigation of solar heating load, and it would thus be
counterproductive to increase a system’s
outside air fraction. ASHRAE 90.1 continues to
wrestle with this, and has thus reduced recommended outside
air amounts since it was first issued in
1975.
The last rating area, Innovation, awarding 4
points in both LEED-EB and LEED-NC, also awards a final point
for having a LEED Accredited Professional (soon to be me?) on
the design team.
OK, that’s LEED.
Any suggestions on what I should write about
next?
Next Issue
|