[Bldg-sim] Heat Recovery Chillers and Lab Outdoor Air

[Matutinovic, Luka]

Sam,

Regarding point 2, I think the fundamental question is: what are the
code ventilation requirements for your facility? The proposed building
may require less total supply air due to efficiency improvements such as
less glazing, but there shouldn't be a difference in the amount of
outdoor air you have to provide.  In fact, in hospital and lab
facilities, the total supply air is often also mandated.  In Canada for
example, patient rooms must provide 2 ACH OA and 6 ACH total supply air.


That's why I think it's important to understand the code requirements.
If there is a code that governs how much outdoor air and total air must
be provided, then the same rates must be used in both proposed and
baseline buildings. Most, if not all, efficiency improvements will
reduce the amount of energy required to condition and move that air, but
the actually amount of outdoor air (and sometimes total air) should be
the same in both buildings, provided that you're not exceeding the
minimum ventilation requirements.  

If a 100% OA system is a designer's/client's choice, but the same
building could be built to the governing code with say 33% OA, the
baseline building will use the minimum code rates, but the proposed
design should get penalized for over-ventilating. What I've found on
previous projects is that the code ventilation rates typically govern
the sizing of air-handling systems, meaning that the heating and cooling
loads can usually be met by the total ACH required by code for infection
control or required as make-up air when the fume hoods are operating. 

I don't know if this has any bearing on ventilation rates and so it may
not help your situation, but I recall seeing a CIR requesting that the
Labs21 modelling requirements be used in lieu of Appendix G since the
latter penalizes lab systems. I think the response from the USGBC was
that the 2007 version of 90.1 addressed particular issues that made it
difficult for labs to get significant savings and therefore Labs21
should not be used.

I hope I haven't muddied the issue further with my comments.

Cheers,

Luka Matutinovic, B.A.Sc., LEED(r) AP
Green Building Consultant / Energy Specialist
 
T. 416.644.0649
F. 416.487.9766  
Toll Free 1.888.425.7255
www.halsall.com 

HALSALL ASSOCIATES LTD. 
Toronto  Richmond Hill  Ottawa  Sudbury 
Burlington  Calgary  Vancouver  Dubai 

'50 Best Workplaces in Canada' 
2009 Globe and Mail
P Please consider the environment before printing this e-mail




-----Original Message-----
From: bldg-sim-bounces at lists.onebuilding.org
[mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Sam Mason
Sent: Monday, October 12, 2009 3:00 PM
To: bldg-sim at lists.onebuilding.org
Subject: [Bldg-sim] Heat Recovery Chillers and Lab Outdoor Air

Thanks in advance for any help.

1. I am trying to model a York heat recovery chiller for a lab facility
and one of the options on the table is adding a second injection rig to
boost the heat recovery capacity of the chiller. When I set the controls
and temperatures for a single rig, it operates closely to what my hand
calcs show for three months of operation in heat recovery mode. However,
I don't know how to boost the heating capacity in heating mode to
simulate the second rig. The heating capacity seems to be limited by the
cooling capacity. Do I need to do hand calcs and provide an exceptional
calculation which accounts for the derated chiller performance and
recovered heat? Any thoughts?

2. For the same lab, the baseline and proposed systems are 100% OA VAV
reheat. After all efficiency measures are included, the total system CFM
for the proposed model is 50,000 CFM less than the proposed, and because
it is a 100% OA system, the baseline system is providing an additional
50,000 CFM of outdoor air. Per ASHRAE G.3.1.2.5, the minimum ventilation
rates shall be the same, but changing the baseline model fundamentally
changes the way a 100% OA lab system is designed to work. If 100% OA is
not provided, then some amount of recirculation is assumed, and for labs
handling sensitive testing and materials, recirculation is not allowed
under any circumstance. Is there a CIR or addenda regarding this issue
in lab modeling? Any thoughts or experience are greatly appreciated.

Sam

--
Sam Mason
Environmental Designer

Atelier Ten
Consulting Environmental Designers
45 East 20th Street, 4th Floor
New York, NY  10003
T +1 (212) 254-4500 x221
F +1 (212) 254-1259
sam.mason at atelierten.com
www.atelierten.com 

_______________________________________________
Bldg-sim mailing list
http://lists.onebuilding.org/listinfo.cgi/bldg-sim-onebuilding.org
To unsubscribe from this mailing list send  a blank message to
BLDG-SIM-UNSUBSCRIBE at ONEBUILDING.ORG