I want to raise the question again about underground garages and IEQc5. The credit clearly says that the exhaust rate should be 0.5 CFM/sf, I understand that. But in Sweden building code says a much much lower rate than that, and I have a hard time motivating projects to go for this credit (they all have underground garages). Has the credit taken into account that we have a cold climate and don’t want to over-ventilate? Has it taken into account that we have CO monitors in the garages? Has it taken into account the travelling patterns of occupants and emissions of their cars? Has it taken into account that no one ever stays in the garage more than a few minutes? It seems a bit stiff to me to say 0.5 CFM/sf for all rooms with hazardous gases, whatever room it is. Does anyone know of an alternative way to comply with this requirement or would like to elaborate what lies behind it?
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Jean Marais
b.i.g. Bechtold DesignBuilder Expert832 thumbs up
October 17, 2013 - 6:16 am
Again, I find issue with redundant requirements. ASHRAE 62.1 requires 0.75 cfm/sf unless the parking garage is more than 50% open on at least 2 sides.
I also find the requirement in ASHRAE 62.1 needs reworking in general. I believe a DCV should be required. The current requirements are IMO too high and a complete waste of energy for low demand times.
Tracy Black
Professional Engineering ConsultantEngineered Solutions
November 4, 2013 - 2:43 pm
Hi Maria,
I understand your situation, I have designed a few underground garages in my time and the balance of energy consumption, temperature, and contamination levels can make for some very interesting performance based solutions.
I understand that the climate in Sweden's winter design temperatures range from -9 C to -17 C, and summer temperatures 25 C to 27 C make for interesting challenges as a mechanical engineer.
I suggest you review chapter 15 in the ASHRAE Applications Handbook (subsection PARKING GARAGES)for ideas to create a performance based solution that both LEED and the AHJ can accept. ASHRAE Ch. 15 goes into simple basis of what they believe should be the contaminant levels should be. Your local AHJ may require lower or allow higher contaminant levels. The key to a solution is how are the variables going to be measured. That should be your first step.
I do not have any direct experience designing in Sweden, however, I have had to solve similar situations.
Sorry for the long answer, but from what I read some of the information I mentioned is not present.