[BLDG-SIM] Natural Ventilation in LEED

[Kofoworola]

Hi All,

Can anyone give me some information /references on the recommended building
air conditioning indoor set point temperature for office buildings in
Tropical countries (example Thailand)?

Many thanks

On 3/30/07, Peter Alspach <peter.alspach at arup.com> wrote:
>
>  Marcus,
>
> I think that this approach to documenting natural ventilation within the
> bounds of Appendix G is the correct one.
>
> However, there are a couple things I'd like to note for future
> consideration:
>
> 1. If the proposed building can stay within the unmet load hours limits
> without a fictitious mechanical cooling system, that should be acceptable,
> provided that budget and proposed models have identical thermostat
> setpoints, etc.
>
> 2. As the USGBC considers project carbon savings and benchmarking of
> buildings versus target finder, I would encourage a broader view on natural
> ventilation and other strategies and the modeling process. In my opinion,
> for this type of comparison the building should be modeled exactly as it is
> to be built and operated - i.e. don't include fictitious mechanical
> systems that are not installed or other such deviations from the as-built
> condition. We already run this type of model for owners so they can see what
> they are really going to expect for energy savings and indoor conditions and
> I suspect that others do the same.
>
> Thanks for the good news.
>
>   Peter Alspach, P.E.
> Associate
> Arup
> 403 Columbia St., Suite 220
> Seattle, WA 98104
> T: 206-493-2226
> C: 206-816-4902
> F: 206-749-0665
> E: peter.alspach at arup.com
>
>  ------------------------------
> *From:* BLDG-SIM at gard.com [mailto:BLDG-SIM at gard.com] *On Behalf Of *Marcus
> Sheffer
> *Sent:* Friday, March 30, 2007 6:45 AM
> *To:* BLDG-SIM at gard.com
> *Subject:* [BLDG-SIM] Natural Ventilation in LEED[Filed 30 Mar 2007 09:36]
>
>  FYI a new CIR has been posted on the USGBC web site regarding natural
> ventilation systems and LEED projects.  The text is below.  Please
> consider this just a starting point and general guidance for projects that
> are similar to the one described.  We welcome feedback.
>
>
>
> *3/22/2007 - *
>
> *Credit Interpretation Request*
> Our project consists of two small buildings close to the ocean that will
> achieve substantial energy savings by incorporating a natural ventilation
> strategy. No mechanical heating or cooling is intended for either building,
> with the exception of a small electrical/server room.
>
> The building is designed with a very narrow and long floor plate situated
> perpendicular to prevailing winds in the area. Ventilation openings are
> consistent with the requirements of ASHRAE 62.1-2004 Section 6.8. The
> project also meets the requirements outlined in the CIBSE Applications
> Manual 10: 2005 as referenced in EQc2 for Natural ventilation in
> non-domestic buildings. Per Title-24 2005 requirements for natural
> ventilation, the sum of operable windows will be greater than 5% of the
> floor area of each space that is naturally ventilated. The openings will
> also be readily accessible to the occupants of each space at all times.
> Outdoor airflow through the openings in regularly occupied spaces will come
> directly from the outdoors, not through intermediate spaces such as other
> occupied spaces or corridors. Openings include operable windows, through-the
> roof ventilators, and vents between interior spaces. Control mechanisms for
> the natural ventilation openings are manual. A long, tall hallway situated
> perpendicular to the prevailing winds will collect heated air and exhaust it
> the outside. The roof over much of the space is sloped allowing air to enter
> on the low side and exit on the high side. In all cases, the building is
> designed to facilitate cross-ventilation with windows low on the walls for
> drawing the air in, and windows and vents high in opposite walls or on the
> roof to draw air out. Under ASHRAE 55 definitions, the building spaces are
> defined as "naturally conditioned spaces, occupant controlled" where the
> thermal conditions of the spaces are regulated primarily by the opening and
> closing of windows or vents by the occupants. Since the building will have a
> limited number of occupants most of the time, manual control of the windows
> and vents has been determined the most appropriate strategy for the building
> to allow control over individual thermal comfort. As indicated by ASHRAE
> 55-2004, section 5.3, the occupants of the space will be engaged in near
> sedentary activities with metabolic rates ranging from 1.0 met to 1.3 met.
> The mean monthly outdoor temperature for the project is greater than 50 deg.
> F, and less than 92.3 deg. F all months of the year, as required under
> ASHRAE 55-2004, section 5.3 for naturally ventilated buildings.
>
> The User's Manual for ASHRAE 90.1-2004 Appendix G states on page G-21: The
> proposed building default cooling system does not exclude natural
> ventilation from consideration. It just means that the proposed building is
> modeled as a hybrid system where cooling is provided by natural ventilation
> when conditions are acceptable and by the default mechanical cooling system
> when natural ventilation is inadequate to provide thermal comfort. We are
> requesting confirmation that the following modeling strategy conforms to the
> requirements of ASHRAE 90.1-2004 Appendix G modeling protocol:
>
> 1. EnergyPlus will be used to model the building since the EnergyPlus
> software has the capability to evaluate energy and comfort parameters tied
> to natural ventilation.
>
> 2. The Exceptional Calculation Methodology will be applied to calculate
> the natural ventilation savings.
>
> 3. The Proposed Design model will be developed to reflect the design
> parameters for the envelope and lighting. Operable windows will be modeled
> as fixed, and vents will not be included in the model. Mechanical systems
> will be modeled identically to the default heating, cooling and fan systems
> in the Baseline case, except that fans in the proposed case will be modeled
> as cycling on and off to meet heating and cooling loads during all hours in
> the proposed case, and will operate continuously during occupied hours in
> the Baseline Case (per the exception shown in Table G3.1.4).
>
> 4. Using the Exceptional Calculation Methodology, The Proposed Design case
> will be modified to include natural ventilation for all hours when the
> cooling and heating loads can be met. Operable windows and vents will be
> modeled as designed. Cooling and heating setpoint temperatures will be
> identical to those in the Baseline Case. Schedules will be adjusted to
> switch on mechanical cooling during hours when natural ventilation alone
> cannot meet the space temperature setpoints. The final model will meet the
> ASHRAE G3.1.2.2 requirements stipulating that the Proposed Design cannot
> exceed the Baseline Design unmet load hours by more than 50, and that unmet
> load hours for the Proposed Design and Baseline Design cannot exceed 300.
>
> 5. (Plan B) If the hybrid system cannot be manipulated to meet the unmet
> load hour requirements within the energy model, hourly output data from a
> natural ventilation model (having no mechanical cooling) and the Proposed
> Design model will be combined in a spreadsheet. Each hour where cooling and
> heating setpoints are met in the natural ventilation model, the hourly
> results for that model will be used. For all other hours, the hourly results
> from the Proposed Design Model will be used.
>
> 6. An Exceptional Calculation Methodology narrative provided with the EAc1
> submittal will document any schedule adjustments and assumptions that were
> made to develop the hybrid system. The savings will also be included as a
> separate line item on the EAc1 submittal.
>
> Is our proposed energy modeling strategy for natural ventilation
> acceptable?
>
>
>
>
>
> *3/22/2007 - *
>
> *Ruling*
> The project is requesting approval for the method of modeling natural
> ventilation as an energy efficiency measure and for taking credit under EA
> credit 1.
>
> Submittals for natural ventilation savings will be evaluated on a case by
> case basis.
>
> The tools and analysis protocol proposed is acceptable for modeling
> ventilation savings in this instance. Other analysis tools may also be
> appropriate.
>
> To be able to adequately document the process and the results, please be
> sure to provide in the LEED submittal the following:
>
> · A detailed project description
> · Clear identification of the areas that are taking credit for natural
> ventilation
> · A detailed description or references that document the modeling
> algorithms and/or methodology for the natural ventilation portion of the
> energy model
> · All thermostat, fan, infiltration and other appropriate schedules for
> naturally ventilated areas
>
> Also, the submitted evaluation must demonstrate that the range of unmet
> load hours is similar for both the proposed and baseline building, to ensure
> that savings are not claimed for hours outside of the control parameters. In
> this case, the project has proposed to meet these peak loads with a
> hypothetical cooling system in the proposed building.
>
> The project will also need to clearly demonstrate that the operational
> schedule for the natural ventilation system as modeled aligns with
> anticipated occupant behavior in terms of scheduled occupancy vs. modeled
> operation. For example, the model cannot assume that natural ventilation
> will occur when no one is in the building to operate the system.
>
> Because manual control is not addressed by the Appendix G modeling
> methodology, the manual control features of this project must be submitted
> under the exceptional calculation methodology for case by case review. The
> project must be prepared to demonstrate convincingly that a manual control
> strategy is appropriate and workable for this project.
>
> Please also be sure to take credit for this measure as a separate item on
> the LEED-NC v2.2 Submittal Template.
>
>
>
>
>
> Marcus Sheffer – Vice Chair USGBC EA TAG
>
> Energy Opportunities, Inc/a 7group Company
>
> 1200 E Camping Area Road, Wellsville, PA  17365
>
> 717-292-2636, sheffer at sevengroup.com
>
> www.sevengroup.com
>
>
>
>
>
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-- 
Kofoworola, O.F.


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