ASHRAE Journal - February 2013 - 12

letters
Standard 90.1 and Health-Care Facilities
August’s “How 90.1-2010 Will Affect Health-Care Facilities”
by Jeff Boldt, Member ASHRAE, claims a simulated energy savings of 32.7% compared to the 90.1-2004 version even though
the fan power limit is now 2.3 hp/1,000 cfm. While meeting the
2004 limit of 1.3 hp/1,000 cfm is difficult with large central AHUs
and VAV terminals, there are less demand-intensive methods
for distributing air. The projected savings seem illogical given
the higher limit results in a net capacity of less than 800 tons
for a 1,000-ton chiller. The fan power would be more than 0.75
kW/gross ton and nearly 1 kW/net ton. Is there any provision in
the new standard to field-verify these savings?
The mechanical section of Standard 90.1 is complex, stifles
innovation and contains numerous exceptions. Compliance is
very difficult, and it would be reassuring to know it is worth the
trouble. It appears the standards committee offers only computer
simulations as evidence. The limited available data that compares
simulation projections with measured results are cause for skepticism. If expected results cannot be demonstrated, the mechanical
section could be simplified with whole building power limits
coupled with performance verification. Would this not allow good
engineers to devote more resources to meeting measurable energy
goals and less time being compliance authorities?
Steve Kavanaugh, Ph.D., Fellow ASHRAE,
Tuscaloosa, Ala.

The Author Responds

www.info.hotims.com/44629-32

12

ASHRAE Journal

The 2.3 bhp/1,000 cfm figure in the article was based on typical allowances for a hospital, such as ducted return, return air
control devices for pressure control, high efficiency filtration,
multiple code-mandated filter banks, energy recovery, etc. It is a
limit on the full load fan power. Under all other load conditions
the requirements for part load fan power in Standard 90.1-2010
reduce this greatly, e.g., to 0.7 bhp/1,000 cfm at 50% airflow rate
for the example where 2.3 bhp/1,000 cfm is allowed at full load.
I agree that fan power is a major issue in hospital design. The
lowest energy consumption hospital that my firm has designed
used lake-coupled geothermal with heat pumps in most areas,
and the fan power savings were huge. However, most owners of
hospitals want HVAC systems that have centralized maintenance.
Field verification of energy consumption has been discussed
within the committee, but there are no provisions in Standard
90.1-2010. Because designers have no control over how owners
operate facilities, we have been reluctant to add such requirements.
The committee has seen proposals about a simple limit on peak
connected load. Since most operating hours are not at peak load,
we have so far used a prescriptive path that considers part load
hours. However, in my opinion the committee would seriously
consider an alternate compliance path based on connected load if
there were ways to ensure building designs under the alternative
path would not consume more energy on an annual basis than
the existing prescriptive compliance path.
Jeff Boldt, P.E., Member ASHRAE,
Monona, Wis.
February 2013



ASHRAE Journal - February 2013

Table of Contents for the Digital Edition of ASHRAE Journal - February 2013

Contents
Commentary
Industry News
Letters
Meetings and Shows
Feature Articles
R-22 Hard Act to Follow: Ammonia Low-Pressure Receiver Systems
Long-Term Commercial GSHP Performance: Part 7: Achieving Quality
Thermally Active Floors: Part 2: Design
Future of DCV for Commercial Kitchens
Standing Columns and Special Sections
Building Sciences
Emerging Technologies
ACREX India 2013 Show Guide
Refrigeration Applications
InfoCenter
Data Centers
IAQ Applications
Special Products
Classified Advertising
Advertisers Index
ASHRAE Journal - February 2013 - Intro
ASHRAE Journal - February 2013 - Cover1
ASHRAE Journal - February 2013 - Cover2
ASHRAE Journal - February 2013 - 1
ASHRAE Journal - February 2013 - 2
ASHRAE Journal - February 2013 - Contents
ASHRAE Journal - February 2013 - Commentary
ASHRAE Journal - February 2013 - 5
ASHRAE Journal - February 2013 - Industry News
ASHRAE Journal - February 2013 - 7
ASHRAE Journal - February 2013 - 8
ASHRAE Journal - February 2013 - 9
ASHRAE Journal - February 2013 - 10
ASHRAE Journal - February 2013 - 11
ASHRAE Journal - February 2013 - Letters
ASHRAE Journal - February 2013 - 13
ASHRAE Journal - February 2013 - Meetings and Shows
ASHRAE Journal - February 2013 - 15
ASHRAE Journal - February 2013 - R-22 Hard Act to Follow: Ammonia Low-Pressure Receiver Systems
ASHRAE Journal - February 2013 - 17
ASHRAE Journal - February 2013 - 18
ASHRAE Journal - February 2013 - 19
ASHRAE Journal - February 2013 - 20
ASHRAE Journal - February 2013 - 21
ASHRAE Journal - February 2013 - 22
ASHRAE Journal - February 2013 - 23
ASHRAE Journal - February 2013 - 24
ASHRAE Journal - February 2013 - 25
ASHRAE Journal - February 2013 - Long-Term Commercial GSHP Performance: Part 7: Achieving Quality
ASHRAE Journal - February 2013 - 27
ASHRAE Journal - February 2013 - 28
ASHRAE Journal - February 2013 - 29
ASHRAE Journal - February 2013 - 30
ASHRAE Journal - February 2013 - 31
ASHRAE Journal - February 2013 - 32
ASHRAE Journal - February 2013 - 33
ASHRAE Journal - February 2013 - 34
ASHRAE Journal - February 2013 - 35
ASHRAE Journal - February 2013 - Thermally Active Floors: Part 2: Design
ASHRAE Journal - February 2013 - 37
ASHRAE Journal - February 2013 - 38
ASHRAE Journal - February 2013 - 39
ASHRAE Journal - February 2013 - 40
ASHRAE Journal - February 2013 - 41
ASHRAE Journal - February 2013 - 42
ASHRAE Journal - February 2013 - 43
ASHRAE Journal - February 2013 - 44
ASHRAE Journal - February 2013 - 45
ASHRAE Journal - February 2013 - 46
ASHRAE Journal - February 2013 - 47
ASHRAE Journal - February 2013 - Future of DCV for Commercial Kitchens
ASHRAE Journal - February 2013 - 49
ASHRAE Journal - February 2013 - 50
ASHRAE Journal - February 2013 - 51
ASHRAE Journal - February 2013 - 52
ASHRAE Journal - February 2013 - 53
ASHRAE Journal - February 2013 - 54
ASHRAE Journal - February 2013 - 55
ASHRAE Journal - February 2013 - Building Sciences
ASHRAE Journal - February 2013 - 57
ASHRAE Journal - February 2013 - 58
ASHRAE Journal - February 2013 - 59
ASHRAE Journal - February 2013 - 60
ASHRAE Journal - February 2013 - 61
ASHRAE Journal - February 2013 - 62
ASHRAE Journal - February 2013 - Emerging Technologies
ASHRAE Journal - February 2013 - 64
ASHRAE Journal - February 2013 - ACREX India 2013 Show Guide
ASHRAE Journal - February 2013 - 64b
ASHRAE Journal - February 2013 - S1
ASHRAE Journal - February 2013 - S2
ASHRAE Journal - February 2013 - S3
ASHRAE Journal - February 2013 - S4
ASHRAE Journal - February 2013 - S5
ASHRAE Journal - February 2013 - S6
ASHRAE Journal - February 2013 - S7
ASHRAE Journal - February 2013 - S8
ASHRAE Journal - February 2013 - S9
ASHRAE Journal - February 2013 - S10
ASHRAE Journal - February 2013 - S11
ASHRAE Journal - February 2013 - S12
ASHRAE Journal - February 2013 - S13
ASHRAE Journal - February 2013 - S14
ASHRAE Journal - February 2013 - S15
ASHRAE Journal - February 2013 - S16
ASHRAE Journal - February 2013 - S17
ASHRAE Journal - February 2013 - S18
ASHRAE Journal - February 2013 - S19
ASHRAE Journal - February 2013 - S20
ASHRAE Journal - February 2013 - S21
ASHRAE Journal - February 2013 - S22
ASHRAE Journal - February 2013 - Refrigeration Applications
ASHRAE Journal - February 2013 - InfoCenter
ASHRAE Journal - February 2013 - 67
ASHRAE Journal - February 2013 - 68
ASHRAE Journal - February 2013 - 69
ASHRAE Journal - February 2013 - 70
ASHRAE Journal - February 2013 - 71
ASHRAE Journal - February 2013 - Data Centers
ASHRAE Journal - February 2013 - 73
ASHRAE Journal - February 2013 - 74
ASHRAE Journal - February 2013 - IAQ Applications
ASHRAE Journal - February 2013 - 76
ASHRAE Journal - February 2013 - 77
ASHRAE Journal - February 2013 - Special Products
ASHRAE Journal - February 2013 - Classified Advertising
ASHRAE Journal - February 2013 - Advertisers Index
ASHRAE Journal - February 2013 - Cover3
ASHRAE Journal - February 2013 - Cover4
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