[Bldg-sim] fossil hybrid or electric

Vinay Devanathan vinay.devanathan at gmail.com
Wed Aug 29 12:13:47 PDT 2012


What would be the case for a project with residences using Heat Pumps for
conditioning and a gas furnace-fired DOAS for ventilation to residences and
common spaces?

Vinay

On Wed, Aug 29, 2012 at 3:09 PM, Maria Karpman <
maria.karpman at karpmanconsulting.net> wrote:

> I think that in Morgan’s case using PTHP baseline is also justified. From
> what I understand, the project is a residential buildings with electrically
> heated living units and gas-heated common spaces. Applying G3.1.1 to the
> project, predominant conditions are residential with electricity as heat
> source; non-predominant conditions are non-residential with fossil fuel
> heat. Based on G3.1.1 exception (a), non-predominant conditions accounting
> for less than 20,000 SF may be ignored when selecting the baseline system
> from Table G3.1.1A, thus the baseline for the project is PTHP. If
> residential units were served by WSHP, then predominant conditions would be
> residential with Fossil/Electric Hybrid heating source, and the baseline
> system would by PTAC.  ****
>
> ** **
>
> Maria****
>
> ** **
>
> *From:* bldg-sim-bounces at lists.onebuilding.org
> [mailto:bldg-sim-bounces at lists.onebuilding.org] *On Behalf Of *Robby
> Oylear
> *Sent:* Wednesday, August 29, 2012 11:14 AM
> *To:* Morgan Heater
> *Cc:* bldg-sim at lists.onebuilding.org
> *Subject:* Re: [Bldg-sim] fossil hybrid or electric****
>
> ** **
>
> Morgan,****
>
> ** **
>
> I agree with Bill.  I find this LEED CIR (see below) to be helpful in
> determining how fossil/electric hybrid systems should be handled.  Your
> scenario sounds similar to item 5 under the examples of systems that would
> be modeled with fossil fuel heating.****
>
> ** **
> LEED Interpretations****
>
> 11/1/2011 *ID#10132*****
>
> **·         **MPR/Prerequisite/Credit: *EAp2: Minimum Energy Performance**
> ***
>
> **·         **Primary Rating System: *Core & Shell v2.0*****
>
> Email<https://www.usgbc.org/leedinterpretations/LIDetails.aspx?oFrfR6EHVoA17nASoM+IzwuZR0PFsDnjdTesCLDRwc3XdlCSQgw1JPBGIDwn9CkFK6O5SmMNy5pahjr+8qQRjE4Hendduw8G5VOxLpTvM9kPskwuXzmeo1a5fJHQ1SxrXbYQ805t/VgRIXV30+vZn5R60DVU60QtJcf/eHkyJd2rmZYILIi6G+4pwsQudobJHVvuEDUecn5jy3Ffs5kuwCxWfL6MVqRf/X1dSpi9MV2g6UFohWlUpH74fdLsOcWi8nWi6XFp6k6xnM3JltWTrWuoHTipDEOGaH+S0w/gCFTtDSWeS6WuMnP+sClrLs11EPDRPZQk7YG0ByU2jL60OAk+2OnOoyExd3WHSOAAyT7r9RVUZydJA6bhS7w9NxvAqdqy9/RC+AGm4cOvquNmAPfOePjVZcypRptO+z4dxQpL2WA9Pb6XcIhrmeaauRqQ/8N1cK9ZiP05YGrznUEpCC+0WskJdy2gLpWU1zHBHdiprHc1WibepyDMttP3xIPLUXrij2SF+a5YxspEjVpQghlbp1jNKDHf3gizux6wShz8f12Scv3O+bNr5BM6amPVgzAR+uElrZFd6xJZ7tQsbtuL7SJV/YwNkYzUJtv5eBvsQvI/un1mImTchxmdG2f6R2OtszajPDxFuTaSnWxZKL5ERZUKNQpH0tEITnsbDemX823YYEiVbyPnzMRxoDzmG1dMLvjuAhswUN1izFndiRHUljYrbMOweh+vzRFijgcHwa/MO8d/zmJ7+LzSUL1euO5yMqommV/WUSIBsSkeBafF76c6ew+1y9+4shlGGAddjikUwnkbctbX56UUXPD/ZfNl93OlLDrjXOrtL+TIH6CvlqaTFSNUqHtJYy4HRIVDqVSyzmPQcjt39kRa3BsGSGYCVxzMiHXzSmUKjOppOI75xT9ELBYiYAQuiXvTo0pPUTHgAWGSS+swMsoEN3WLbrOZK/TagwMC+6qDyrjYYgivWLEQG/UjwFPzYK8tINdf619BhVztcceR623dv7YBH/zs91TmFY+qJFWMeoghoe7hbXGSumnMoOci79BuAAOTzVsshKMZjAFAjUOsWVnJWubEn9RZBjM0AF2rtShOIIzWDXYENjs9iD9gPo3983R7joNzc/FilhIiz+J/xUbaUjEsLuIg7OEfUxdIx6UYxkBRYgGWHbZALCrGtdEghkFSkQSUWH7v+b/fxwgFGDYuGMiuT/GeaDvkcoBXahZlFxXmGE5zUCnnwzrdFADNxu6mk1fDOC2Y9nx1sr3JbV82MvDsq+4t0sSchXpxHBKQMt4h7zJ1embW/vLVKMsSAIknk5xvJkOgjr5LdUcJl8+LwIQBs9W4ZTGcE2KbO5Kyeb1kR4V7dV4IbgchbamBKRB6Vvh88P0h9/xWEt1+fUWnO7k9P3qd9wOK0rObMKfqyrn28dvASdI3wCNNUM2RgA7lD7bMutlA4HuFF+JmOyDp0c1DJy8keCX99E3ijUyVumWdJ48ZDdnrXSq7+Vzv3Sng0qeGeaJSmRH0Rv5aE4aSu9pD9u6g2F46lApF1T42pvtcayOeyKvqXdCG/gQ9FZqO97sPXi2ZmbmQmJVVIJPuM/K9a9jDQqunHFvLcZHJ4OJbxrJ3WXjMEgmtag2xDQigw8OuHSy4ntXIQoa4FVS5UifmYkRlsl0M0/iQNVqKqvP5VARbA2Wjqz0tQyxweD+3mDyqIF8V0F24t+yu3PwKd04FN4yvCJ3LaN9+66/N5EzGH94Gp4gXDMGNoyHWA9OOgVm23LZr1dOsO+Tuj8jiNaOWzFOdjXiKwrFJjeGS/ewyaXExsx3CELdX+6NtlQwhBrxmjyePnMiGjjLxWy9o>
> ****
> Ruling****
>
> Clarification is requested regarding when a building heat source in Table
> G3.1.1A should be identified as "Fossil/Electric Hybrid" versus "Electric".
>
> The ASHRAE 90.1-2007 User's Manual states that a fossil/electric hybrid
> source "refers to a system with any combination of fossil and electric
> heat, and the baseline system for this is a fossil fuel system". Therefore,
> the heating source for the proposed building would be considered "Fossil
> Fuel" or "Fossil/Electric Hybrid" if the building uses any fossil fuel
> source for space heating (including backup heating or preheating), and the
> baseline building heat source would be fossil fuel.
>
> Exception: ASHRAE 90.1 Section G3.1.1 Exception (a) stipulates additional
> system type(s) for non-predominant conditions (i.e.
> residential/non-residential or heating source) if those conditions apply to
> more than 20,000 square feet of conditioned floor area.
>
> EXAMPLES OF BASELINE HEATING SOURCE DETERMINATION:
>
> The Baseline heat source from Table G3.1.1A for the following Proposed
> Case system types would be fossil fuel since the proposed system design
> includes a combination of fossil and electric heat:
>
> 1. Variable air volume system with gas furnace preheat and electric reheat
> 2. Packaged terminal heat pumps with outside air tempered by fossil fuel
> furnace
> 3. Water source heat pumps with fossil fuel boiler
> 4. Ground source heat pumps with backup fossil fuel boiler
> 5. 90,000 square feet is conditioned by a variable air volume system with
> electric reheat, and 10,000 square feet is conditioned with fossil fuel
> furnaces
>
> The following buildings would be modeled with an additional system type
> with a different Baseline heating source in accordance with Section G3.1.1
> Exception (a):
>
> 1. 90,000 square feet is conditioned by a variable air volume system with
> electric reheat, and 20,000 square feet is conditioned with Packaged DX
> systems with fossil fuel furnaces. In this case, the 90,000 square feet of
> area would be modeled with an electric heat source in the Baseline Case
> (System Type #6 - Packaged VAV with Electric PFP Boxes), and the 20,000
> square feet of area would be modeled with a fossil fuel heat source in the
> Baseline Case (System Type #3 - Packaged Single Zone AC with fossil fuel
> furnace).
> 2. 50,000 square feet is conditioned by water source heat pumps with a
> fossil fuel boiler, and 25,000 square feet is conditioned by electric heat
> pumps. In this case, the 50,000 square feet of area would be modeled with a
> fossil fuel heat source in the Baseline Case (System Type #5 - Packaged VAV
> with hot water reheat), and the 25,000 square feet of area would be modeled
> with an electric heat source in the Baseline Case (System Type #4 -
> Packaged Single Zone Heat Pump).
>
> Applicable Internationally.****
> Formal Inquiry****
>
> Table G3.1.1A lists two possible categories for the building heating
> source:
> (1) Fossil fuel, fossil/electric hybrid, & purchased heat;
> (2) Electric and other.
>
> In cases where the proposed building design includes both a natural gas
> heating source and an electric heating source, when should the heat source
> in Table G3.1.1A be identified as "Fossil/Electric Hybrid" versus
> "Electric"?****
>
> Robby Oylear, PE, LEED AP****
>
> *Mechanical Engineer*****
>
> *Senior Energy Analyst*****
>
> * *****
>
> *D* 206-788-4571****
>
> *www.rushingco.com* <http://www.rushingco.com/>****
>
> ** **
>
> On Tue, Aug 28, 2012 at 5:41 PM, Bishop, Bill <bbishop at pathfinder-ea.com>
> wrote:****
>
> Morgan,****
>
>  ****
>
> My vote is for PTAC with hot-water boiler.****
>
>  ****
>
> Regards,****
>
> Bill****
>
>  ****
>
>   <wbishop at pathfinder-ea.com>****
>
> *From:* *bldg-sim-bounces at lists.onebuilding.org* [mailto:*
> bldg-sim-bounces at lists.onebuilding.org*] *On Behalf Of *Morgan Heater<wbishop at pathfinder-ea.com>
>
> *Sent:* Tuesday, August 28, 2012 8:12 PM
> *To:* *bldg-sim at lists.onebuilding.org*
> *Subject:* [Bldg-sim] fossil hybrid or electric<wbishop at pathfinder-ea.com>
> ****
>
>   <wbishop at pathfinder-ea.com>****
>
> Hi – I’ve got an appendix G baseline system question.  Here’s the
> scenario, let me know what you think.  <wbishop at pathfinder-ea.com>****
>
>   <wbishop at pathfinder-ea.com>****
>
> Proposed Building: <wbishop at pathfinder-ea.com>****
>
>   <wbishop at pathfinder-ea.com>****
>
> 1.       Multi-family residential, amenity/common space < 20,000 square
> feet <wbishop at pathfinder-ea.com>****
>
> 2.       Electric baseboard heat in the units <wbishop at pathfinder-ea.com>*
> ***
>
> 3.       Condensing gas furnaces in the corridors and back of house spaces<wbishop at pathfinder-ea.com>
> ****
>
> 4.       VRF in amenity common spaces <wbishop at pathfinder-ea.com>****
>
>   <wbishop at pathfinder-ea.com>****
>
> My understanding is that because my non-predominant condition
> (common/amenity space) is less than 20,000 square feet, I use a single
> system for the whole baseline building (G3.1.1a).  I’ve got a mix of gas
> and electric heat in the baseline building,  does this mean that my base
> system is PTAC with a hot water boiler? <wbishop at pathfinder-ea.com>****
>
>   <wbishop at pathfinder-ea.com>****
>
> Thanks!  <wbishop at pathfinder-ea.com>****
>
>   <wbishop at pathfinder-ea.com>****
>
>   <wbishop at pathfinder-ea.com>****
>
> Morgan Heater, P.E. <wbishop at pathfinder-ea.com>****
>
> BEMP, LEED AP <wbishop at pathfinder-ea.com>****
>
> *morgan at ecotope.com* <wbishop at pathfinder-ea.com>****
>
> *206-322-3753 ext 209* <wbishop at pathfinder-ea.com>****
>
>   <wbishop at pathfinder-ea.com>****
>
>
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> **** <wbishop at pathfinder-ea.com>
> ------------------------------
> <wbishop at pathfinder-ea.com>
>
> ** **
>
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-- 
Vinay Dev
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