First of all, changing the R-value of walls and roofs can have a significant impact on overall energy use, especially in locations with extreme outdoor conditions. Granted, with more ventilation air required, the envelope is responsible for a smaller piece of the overall energy use of the building.<br>
<br>So, to reduce ventilation air energy use:<br><br>A. Use energy recovery ventilation! In moderate climates, energy recovery ventilation might not make a whole lot of sense, but climates where heat is needed much of the year, ERV's make a lot of sense!<br>
<br>B. Turn off the ventilation when it's not needed! This includes time clocks and CO2 sensors. I've seen alot of schools with old unit ventilators in each classroom. These unit ventilators often stay on all night, bringing cold air into the classroom and wasting tons of heat!<br>
<br>Regarding your CO2 questions:<br><br>1. Decoupling the ventilation air distribution system from an airside air conditioning system allows for the most options. Installation of CO2 sensors in each space with corresponding ventilation air VAV supply results in ventilation air being supplied only where it's needed. But, this can be cost-prohibitive, and where lots of spaces see similar occupancy, completely unnecessary.<br>
<br>2. It is permissible to vary the CFM between the base case and design case for ASHRAE 90.1-2004 Appendix G (G.3.1.2.5 Exception), some programs, including eQuest model DCV, so no change in ventilation rate is required, just activation of DCV.<br>
<br>3. In a building with 40 classrooms, you could create one branch of each type of space (classrooms, offices), and control ventilation to each block of spaces. For high-use areas with varying schedules (caffeteria, gymnasium and auditorium), have each space have it's own demand controlled ventilation.<br>
<br>5. If you model this in eQuest, you can still do blocks of classrooms, especially if your occupancy schedule is the same for each classroom.<br><br>Hope this helps,<br><br>--<br>Karen<br><br><br><br><div class="gmail_quote">
On Wed, Jan 14, 2009 at 12:01 PM, James Geers <span dir="ltr"><<a href="mailto:jgeers@sfa-architects.com">jgeers@sfa-architects.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
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<p><font size="2" face="Arial"><span style="font-size: 10pt; font-family: Arial;">Previous posts have confirmed my suspicions that increasing
the R-value of walls and roofs has little to no effect on energy performance,
due to the outside air requirements. </span></font></p>
<p><font size="2" face="Arial"><span style="font-size: 10pt; font-family: Arial;"> </span></font></p>
<p><font size="2" face="Arial"><span style="font-size: 10pt; font-family: Arial;">This raises a few questions:</span></font></p>
<p><font size="2" face="Arial"><span style="font-size: 10pt; font-family: Arial;"> </span></font></p>
<p style="text-indent: 0.25in;"><font size="2" face="Arial"><span style="font-size: 10pt; font-family: Arial;">1. What is the most
effective way to use CO2 sensors to dramatically reduce the outside air requirements?</span></font></p>
<p><font size="2" face="Arial"><span style="font-size: 10pt; font-family: Arial;"> </span></font></p>
<ol style="margin-top: 0in;" start="2" type="1">
<li><font size="2" face="Arial"><span style="font-size: 10pt; font-family: Arial;">Is it permissible to vary the CFM
between the base case and design case in the ASHRAE 90.1-2004 Appendix G
model, and consequently in the LEED template?</span></font></li>
</ol>
<p><font size="2" face="Arial"><span style="font-size: 10pt; font-family: Arial;"> </span></font></p>
<ol style="margin-top: 0in;" start="3" type="1">
<li><font size="2" face="Arial"><span style="font-size: 10pt; font-family: Arial;">What is the most effective way
to use CO2 monitoring in a building with 40 classrooms and other large
spaces. If one sensor is triggered, won't the entire zone get
fresh air and defeat the energy savings?</span></font></li>
</ol>
<p><font size="2" face="Arial"><span style="font-size: 10pt; font-family: Arial;"> </span></font></p>
<ol style="margin-top: 0in;" start="4" type="1">
<li><font size="2" face="Arial"><span style="font-size: 10pt; font-family: Arial;">If every classroom has a
sensor, does any one have experience with the replaceable / Mail in
sensors to assure their accuracy.</span></font></li>
</ol>
<p><font size="2" face="Arial"><span style="font-size: 10pt; font-family: Arial;"> </span></font></p>
<ol style="margin-top: 0in;" start="5" type="1">
<li><font size="2" face="Arial"><span style="font-size: 10pt; font-family: Arial;">If I model this in Equest, do I
need a zone for every classroom.</span></font></li>
</ol>
<p><font size="2" face="Arial"><span style="font-size: 10pt; font-family: Arial;"> </span></font></p>
<p><font size="2" face="Arial"><span style="font-size: 10pt; font-family: Arial;">Thank you for any feed back.</span></font></p>
<p><font size="2" face="Arial"><span style="font-size: 10pt; font-family: Arial;"> </span></font></p>
<p><font size="4" color="navy" face="Tahoma"><span style="font-size: 13.5pt; font-family: Tahoma; color: navy;">James F. Geers</span></font><font face="Tahoma"><span style="font-family: Tahoma;"></span></font></p>
<p><b><font size="2" color="navy" face="Tahoma"><span style="font-size: 10pt; font-family: Tahoma; color: navy; font-weight: bold;">Registered Architect</span></font></b><b><font face="Tahoma"><span style="font-family: Tahoma; font-weight: bold;"></span></font></b></p>
<p><b><font size="2" color="navy" face="Tahoma"><span style="font-size: 10pt; font-family: Tahoma; color: navy; font-weight: bold;">LEED Accredited Professional</span></font></b></p>
<p><b><font size="3" face="Tahoma"><span style="font-size: 12pt; font-family: Tahoma; font-weight: bold;"> </span></font></b></p>
<p><b><font size="2" color="navy" face="Tahoma"><span style="font-size: 10pt; font-family: Tahoma; color: navy; font-weight: bold;">SFA Architects</span></font></b><b><font face="Tahoma"><span style="font-family: Tahoma; font-weight: bold;"></span></font></b></p>
<p><b><font size="2" color="navy" face="Tahoma"><span style="font-size: 10pt; font-family: Tahoma; color: navy; font-weight: bold;">300
West Fourth Street</span></font></b><b><font face="Tahoma"><span style="font-family: Tahoma; font-weight: bold;"></span></font></b></p>
<p><b><font size="2" color="navy" face="Tahoma"><span style="font-size: 10pt; font-family: Tahoma; color: navy; font-weight: bold;">Cincinnati</span></font></b><b><font size="2" color="navy" face="Tahoma"><span style="font-size: 10pt; font-family: Tahoma; color: navy; font-weight: bold;">, Ohio 45202</span></font></b><b><font face="Tahoma"><span style="font-family: Tahoma; font-weight: bold;"></span></font></b></p>
<p><b><font size="2" color="navy" face="Tahoma"><span style="font-size: 10pt; font-family: Tahoma; color: navy; font-weight: bold;">513.721.0600</span></font></b><b><font color="navy" face="Tahoma"><span style="font-family: Tahoma; color: navy; font-weight: bold;">
</span></font></b><b><font face="Tahoma"><span style="font-family: Tahoma; font-weight: bold;"></span></font></b></p>
<p><b><font size="2" color="navy" face="Tahoma"><span style="font-size: 10pt; font-family: Tahoma; color: navy; font-weight: bold;">513.721.0611 (fax)</span></font></b><b><font face="Tahoma"><span style="font-family: Tahoma; font-weight: bold;"></span></font></b></p>
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