Exhaust & Sprinkler Density for Electric Parking?

8/23/2022

I am currently reviewing plans for a 6-story condominium project with two levels of underground parking coming up in Ontario, Canada.

The drawings show provisions for 42 electric vehicle parking spots (assuming a Level 2 charger included) in the underground parking garage.

I have read the NFPA document on modern vehicles in parking structures and I was wondering if there any recommendations on what to look out for with the mechanical exhaust system or the sprinkler system designed for this particular area of the building?

Stay safe, thanks.

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10 Comments

Dan Wilder

8/23/2022 07:56:17 am

Couple things come to mind for the sprinkler side:

The 2022 NFPA 13 classifies Parking Garages as OH2 (up from OH1)

You may want to look into an approach of higher density/smaller max sq. ft. coverage/larger k-factor for the electric charging area not specific to a single car event, but to prevent extension of the fire to adjacent vehicles. This would be more a performance based approach needing an FPE while the applicable NFPA's catch up to the emerging technologies.

https://www.nfpa.org/-/media/Files/News-and-Research/Resources/Research-Foundation/Current-projects/ProjectSummaryEVParkingGarages.ashx

https://www.nfpa.org/News-and-Research/Data-research-and-tools/Building-and-Life-Safety/Modern-Vehicle-Hazards-in-Parking-Garages-Vehicle-Carriers

Glenn Berger

8/23/2022 08:06:36 am

Need to ensure that the electrical design accounts that 100% of the chargers can be in use at the same time. Need to ensure that the charges are protected from physical damage.

The sprinkler design portion of the facility is standard use of the area/density method using criteria out of NFPA 88A.

Todd E Wyatt

8/23/2022 08:26:47 am

The National Building Code of Canada (NBC) calls parking garages “storage garages” and requires the following ventilation :

3.3.5. Industrial Occupancy
3.3.5.4. Repair and Storage Garages
4) A garage shall be provided with natural or mechanical ventilation in conformance with the requirements of Subsection 6.3.1. and Article 6.9.1.2. to prevent excessive accumulation of carbon monoxide, exhaust fumes or flammable and toxic vapours.

Section 6.3. Ventilation Systems
6.3.1. Ventilation
6.3.1.1. Required Ventilation
2) Except in storage garages covered by Article 6.3.1.4., the rates at which outdoor air is supplied in buildings by ventilation systems shall be not less than the rates required by ANSI/ASHRAE 62, “Ventilation for Acceptable Indoor Air Quality” (except Addendum n).

6.3.1.4. Ventilation of Storage Garages
1) Except as provided in Sentences (4) and (6), an enclosed storage garage for five or more motor vehicles shall have a mechanical ventilation system designed to
a) limit the concentration of carbon monoxide to not more than 100 parts per million parts of air,
b) limit the concentration of nitrogen dioxide to not more than 3 parts per million parts of air, where the majority of the vehicles stored are powered by diesel-fuelled engines, or
c) provide, during operating hours, a continuous supply of outdoor air at a rate of not less than 3.9 L/s for each square metre of floor area (see Article 3.3.1.20.).
(See also Sentence 3.3.5.4.(4).) (See Note A-6.3.1.4.(1).)
2) Mechanical ventilation systems provided in accordance with Clause (1)(a) shall be controlled by carbon monoxide monitoring devices, and systems provided in accordance with Clause (1)(b) shall be controlled by nitrogen dioxide or other acceptable monitoring devices. (See Note A-6.3.1.4.(2).)
3) Mechanical ventilation systems provided in accordance with Sentence (1) shall be designed such that the pressure in the storage garage is less than the pressure in adjoining buildings of other occupancy, or in adjacent portions of the same building having a different occupancy.
4) In storage garages subject to the requirements of Sentences (1) and (2), where motor vehicles are parked by mechanical means, the ventilation requirements may be reduced by one half.
5) Except as provided in Sentence (6), ticket and attendant booths of storage garages shall be pressurized with a supply of uncontaminated air.
6) The requirements of Sentences (1) to (5) shall not apply to open-air storeys in a storage garage.

A-6.3.1.4.(2) Ventilation of Storage Garages. Storage garages are ventilated to protect occupants from exposure to carbon monoxide and other vehicular exhaust fumes. In certain cases, such as small two or three-bay storage garages that are used for occasional vehicle storage, and where occupants are not present, carbon monoxide or nitrogen dioxide monitoring devices may be omitted if the ventilation system is interlocked with a local light switch or other controls to ensure continuous system operation whenever the area is occupied. In any event, the ventilation system capacity must be designed to limit the concentrations of carbon monoxide or nitrogen dioxide at or below the prescribed values.

Franck

8/23/2022 09:14:33 am

You can also have a look at NFPA Journal – 2019 March/April issue – Ramp Risk (probably available through NFPA website).

As well as the following lonks for parking structure fires:
https://maritimecyprus.com/wp-content/uploads/2017/07/courage-fire-investigation-report-1.pdf

https://www.nfpa.org/News-and-Research/Publications-and-media/NFPA-Journal/2019/March-April-2019/Features/Protecting-Parking-Garages

https://www.bbc.com/news/uk-england-merseyside-46290095

https://risefr.com/media/publikasjoner/upload/2020/rise-report-2020-91-evaluation-of-fire-in-stavanger-airport-cark-park-7-january-2

Franck

8/23/2022 09:11:52 am

I would be very conservative for a new project.

First, even with "classical cars", the occupancy has greatly changed. And there are many reasons :
- cars have less metal parts and more plastic (bumpers, sides...)
- cars are full of electyronic components (plastic again)
- Even the fuel tank is now made of plastic when it was metal in the past
This results in larger and quicker spread fires than before.
There was an old rule saying that if parkings were open on the sides, sprinklers could be omitted. Because the fire was not developping fast and manual firefighting were deems sufficient.
But more and more vety big parking fires occured since then. And the more revnt are the most desastrous.

To be honest, I would recommend you at least the follwowing sprinkler protection:
based on an extra hazard occupancy and should be able to deliver a minimum density of 0.3 gpm/ sq ft over 2500 sq ft for a wet pipe system, or 3250 sq ft for a dry pipe system.
Sprinkler heads should have a minimum K-factor of 8.0.

I made an analysis a few months ago and I noted the following:
According to NFPA 13 (2019 Edition), parking structures should be protected as an Ordinary Hazard Group 1 occupancy, with a density of 6 mm/min over 186 m2 (0.15 gpm/sq ft over 2000 sq ft) for a wet system, or over 242 m2 (2600 sq ft) for a dry system.
This was based on the way vehicles were constructed until the 80’s, with a major use of metal components.
Because of major changes in the composition of modern vehicles, the hazard exposure has completely changed.
The transition began in the 1960s on the vehicle interior, as softer materials and padded dashboards were desired over steel dash panels for crash protection.
Main difference are:
- Extensive use of electronic components, increasing the combustible load with wiring and electronic components
- Use of plastic parts for the vehicle body, to gain weight, for better corrosion resistance or for people safety, such as the front and back ends (bumpers) that used to be made of metal and are now made (since the 19710s) of expanded plastic foams (urethane) and plastic.
- Use of plastic fuel tanks - now standard on about 80 percent of vehicles – that can melt when exposed to a fire, and then rupture and send the entire gasoline content to the ground, contributing to a combustible/flammable liquid spill pool fire.

Modern vehicles are now composed of about 50 percent plastic by volume, even though plastics account for only 10 percent of the average vehicle’s weight.

In addition, there is a growing concern with alternative fuels such as CNG, LNG, LPG or hydrogen, that present potential for explosion hazards (BLEVE effect) when exposed in a fire event, and electric car with the use of lithium-ion batteries that present an additional fire hazard and ignition source.

A typical garage fire today is much more likely to involve multiple vehicles than two decades ago. In addition, fires are burning with more severity and are much harder to extinguish.

A study made in, France showed that in garage fires between 1995 and 1997, 98 percent involved fewer than four vehicles; only 1 percent of fires involved more than five vehicles, and none of the fires reviewed involved more than seven vehicles.
By contrast, 8 percent of the garage fires between 2010 and 2014 involved more than five vehicles, and 6 percent involved more than seven vehicles.

The same study showed that in 1997, 95 percent of garage fires analyzed were extinguished in under 60 minutes. However, in French garage fires occurring between 2010 and 2014, only 40 percent were extinguished in under an hour; 30 percent of the fires took more than two hours to extinguish, and 10 percent took more than four hours.
By contrast, fewer than 1 percent the 1997 fires took longer than two hours to put out.

Franck

8/23/2022 09:20:07 am

In addition to my above comments, electric vahicles have more problems.

It is almost impossible to extinguish the fire (unless you put the car into a container full of water for several hours).

A density of 0.3/2500 as for lithium ion battery facilities (• NFPA 855 - Standard for the Installation of Stationary Energy Storage Systems) is not too conservative, believe me...

you can have a look at:
https://www.nfpa.org/News-and-Research/Publications-and-media/NFPA-Journal/2020/January-February-2020/Features/EV-Stranded-Energy

and

https://www.nfpa.org/batteredbatteries

Kostas Papapostolou

8/23/2022 10:12:02 am

Dear sirs
What about the new garages which include electrical motors since the fire in the battery part cannot be extinguished with water?

martin moffitt

8/23/2022 10:28:02 am

"Assuming?" do not assume anything, especially in a case like this.
Good luck with your project Sir

Tim

8/24/2022 01:59:09 am

The fact is that a sprinkler system is likely not to extinguish a fire involving a EV. If that is the case and we need to contain fire to area of origin for extended period of time more than 60 minutes then perhaps a low density larger area approach must be considered. Similar to a Aircraft Hanger where cooling over exposure risk will prevent spread with sprinkler system not design to extinguish the original vehicle that ignited. Smoke control is critical smoke dilution with extraction shafts included if the space is underground or a basement.

NFPA 588 is more focused Stationary Energy Storage which applies but not limited to UPS or battery rooms commonly found in data centres for example where more density small area approach most certainly applies.

My view is we need more testing and case studies but the cost challenge to do large scale EV testing remain for now. I know larger organizations have in the management plan allowed for means of EV extraction from parking spaces in buildings to a safe burn off area external to the building for example. But you must design for an environment that allow fire fighters to access the space and extra equipment like high temperature fire sheets to cover the entire EV before extraction.

Dale

8/24/2022 12:24:22 pm

I am currently working on a parking garage, that will utiize car stackers. The stackers will allow for 4 levels of vehicles. There is no current precedent, as NFPA only recently started covering 2 levels of stacked vehicles. We are treating this as a storage space. We are providing ESFR sprinklers at the roof deck, and creating a sidewall sprinkler system with the sprinkler located just under the floor of the stacker. We performed a calculation, having both systems included, to try to anticipate a real scenario.

Exhaust & Sprinkler Density for Electric Parking?

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