ASHRAE90.1 AppendixG: All conditioned spaces in the proposed design shall be simulated as being both heated and cooled even if no heating or cooling system is to be installed.
After all this time, I would like to discuss the requirement mentioned in the title. The requrement is in ASHRAE90.1 AppendixG Table G3.1.
- Why do we have to simulate both heating and cooling even if no heating or cooling system is to be installed?
- For buildings without heating system in tropical climate, normally I use
ThermostatSetpoint:DualSetpoint, but I set the Heating Setpoint Temperature Schedule very low such as -100ºC. Is this the correct approach to comply with this requiremnt?
Answers to only one of the two questions are also appreciated.
Hi Keigo. Isn't the requirement in (b) limited to conditioned spaces, i.e. cooled spaces, heated spaces, or indirectly conditioned spaces? The requirement would not apply to semi-heated spaces or unconditioned spaces, right?
@Denis Bourgeois Right.
It applies to cooled only space, but I'm wondering if there is a reasonable background to this requirement, and I'm not so confident in my modelling approach.
Hey Keigo. My first comment applied only to Q1 (i.e. NO heating & NO cooling), hence requirement (b) doesn't apply. For Q2 (cooling ONLY, therefore conditioned), requirement (b) does apply : virtual heating system (same as baseline). It's also my understanding that one can set the heating setpoint low enough so heating doesn't kick in (in both design & baseline), as you suggest. It'd be nice to quote an official LEED ruling on this ...
For Q2, do you think we should model virtual heating system? For example, VAV with Reheat although the actual design does not have Reheat coils? Even if we should do so, I think we eventually need to set the heating setpoint low enough so heating doesn't kick in because there is no actual heating setpoint and heating energy consumption should be 0. Then, I think there is no point in modeling the virtual heating system...
It's not what I think, it's simply what's stated in AppG (TG3.1, 10c, v2016, proposed building) : "Where no heating system exists or no heating system has been submitted with design documents, the system type shall be the same system as modeled in the baseline building design and shall comply with but not exceed the requirements of Section 6." I agree that it's pointless if you're setting the heating setpoint below freezing in a tropical climate. Maybe chat with the building official ... :]
oh, Table G3.1, 10. HVAC Systems, c. I understand, and I agree.
On the other hand, the requirement for thermostat setpoint in Table G3.1 4. Schedule just says "Temperature and Humidity Schedules. Temperature and humidity control set points and schedules as well as temperature control throttling range shall be the same for proposed design and baseline building design." Then, I think we can set the heating setpoint very low...
Even when the building actually has heating and cooling system , I often set heating setpoint very low(-100ºC) and cooling setpoint very high(100ºC) during unoccupied hours so that the HVAC system does not turn on duting unoccupied hours, which is the same approach to my Q2.
Can't argue with that. One finds similar ideas in other forums. I don't think 90.1 holds prescriptive requirements on comfort setpoint temperature thresholds (in absolute degC). There are a few in Section 6, yet always relative to user-defined setpoints. There may be rulings elsewhere (e.g. USGBC), but I can't find them. In the meantime, I think you're OK. Good luck!
@Denis Bourgeois Thank you so much for the long chat!
Hello everybody, currently I am working in a residential building in Ireland and due to the weather it does not have cooling at all. I though to do the same as someone mentioned before, install the same cooling system in the proposed and set a high set point temperature, preventing the cooling system from turning on. However, by following the simulation guidelines for multifamily projects, it say that: "The following setpoints shall be used for dwelling unit spaces: Heating: 12-7am: 70 degrees; 7am – 11pm: 72 degrees; 11pm-12am: 70 degrees /Cooling: 12-9am: 78 degrees; 9am – 3pm: 80 degree".
What would you do in this case? Do you consider these set point temperatures are "mandatory requirements"? If so, would it be possible to justify other values?
@santiago.avila@in2engineering.com, hard to say without knowing more about the technical requirements. If it's code in Ireland, wouldn't it be a set of EPBD-related requirements? A quick glance didn't reveal any obvious rules for room setpoints. I'd contact the Department, or else ask a separate (non-AppG) question.