We are pursuing LEED V4 NC Certification for a building that is part of a University Campus.
The project is located in Lima, Peru, where the climate is ideal for natural ventilation and often not even cooling, and especially no heating is needed, which is our case. So we have a project which is only naturally ventilated, without heating/cooling.
To comply with the option of whole building simulation to obtain the credit we are encountering some problems..
1.) On the one hand, we are not entirely sure how to model the HVAC system, for the energy consumption comparison:
a.) Is it ok, to simply not model any HVAC system, neither in the Proposed building nor the Baseline building?
or
b.) Do both buildings have to be modeled with X-Hvac system, which, due to either high temperature setpoint or schedule configuration, never turns on and therefore does not register any consumption?
> ideally both options have the same result = zero registered energy consumption, it's mostly a question of procedure--
2.) On the other hand, if there are no energy consumptions and consequently no energy saving when not using any HVAC system, savings can only be achieved through components such as lighting.. Is it possible to claim savings that are only due to lighting? or are there any other conditions required to fulfil?
Further, how could the savings for natural ventilation be claimed?What are the conditions to be able to claim them and in what range do the unmet hours of comfort have to be?
Dang Thi
ESD EngineerGreenViet Consultancy Company
3 thumbs up
June 4, 2020 - 10:01 pm
Hi,
By my exprerience, in your case, you still have to model without cooling / heating system. However, you must to model some supply/exhaust fan if your design have.
Generally, your project will be earn energy saving by the lighting and it should be get the minimum 5% energy savings (It'll easy if you are using 100% LED lighting).
On the other hand, you can install PV system to get more points.
Francesco Passerini
3 thumbs up
June 5, 2020 - 9:08 am
Hello, consider the following statements of table TABLE G3.1, point 10:
c. Where no heating system exists or no heating system has been specified, the heating
system classification shall be assumed to be electric, and the system characteristics
shall be identical to the system modeled in the baseline building design.
d. Where no cooling system exists or no cooling system has been specified, the cooling
system shall be identical to the system modeled in the baseline building
design.
Exception to d: Spaces using baseline HVAC system types 9 and 10.
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5868 thumbs up
June 5, 2020 - 9:49 am
1. Since your 1b is a clear option it makes no sense to model an HVAC system in either case. Why waste your time doing so?
2. You still must include all energy use in the models and claim savings related to that energy use. If you want to claim savings for natural ventilation then you will need to justify the baseline you are using for comparison. As far as I know GBCI does not have an approved methodology for claiming savings related to natural ventialtion.
Santiago Sánchez Sánchez
Mechanical engineerSUMAC
2 thumbs up
June 9, 2020 - 4:13 pm
As you said, the weigh of the HVAC in the total energy use remains very low, nevertheless you can claim savings for passive cooling systems such as natural ventilation (make sure you support your model with bioclimatic reports or natural ventilation calculations). We have done several projects with natural ventilation in Bogota, Colombia, (similar weather conditions) claiming savings for natural ventilation (with ECMs).
As Francesco said, if no HVAC is specified, baseline and proposed model should be identical, so I advise you to model a mixed HVAC system in your proposed model, and so the mechanical HVAC system must turn on whenever natural ventilation does not give thermal comfort.
See how much the HVAC weighs in your baseline energy use, and you´ll see if it´s worth it or not.
Regarding the remaining systems, you might also claim savings with the hot water systems.