David Elfstrom 🍁
@davidelfstrom.bsky.social
P.Eng, Energy management, measurement & verification. Toronto, Canada. Born 327ppm CO2. Climate Action & electrification; Safer infrastructure; cycling; air filtration & ventilation
Forlorn gated entrance to the pedestrian bridge leading to Ontario Place from the exhibition grounds in Toronto. Signage in French and English describes the project ... /1
November 22, 2025 at 2:12 PM
Forlorn gated entrance to the pedestrian bridge leading to Ontario Place from the exhibition grounds in Toronto. Signage in French and English describes the project ... /1
HORSES
Art Deco entrance to the Horse Palace at Toronto's exhibition grounds, at twilight. Lit in yellow-blue complementary colours.
Art Deco entrance to the Horse Palace at Toronto's exhibition grounds, at twilight. Lit in yellow-blue complementary colours.
November 22, 2025 at 1:50 PM
HORSES
Art Deco entrance to the Horse Palace at Toronto's exhibition grounds, at twilight. Lit in yellow-blue complementary colours.
Art Deco entrance to the Horse Palace at Toronto's exhibition grounds, at twilight. Lit in yellow-blue complementary colours.
Reposted by David Elfstrom 🍁
We went from “you can’t trust anything on Wikipedia” to it being one of the only places on the web that’s likely to be correct and unbiased more often than wrong or driven by private interests.
November 21, 2025 at 5:09 PM
We went from “you can’t trust anything on Wikipedia” to it being one of the only places on the web that’s likely to be correct and unbiased more often than wrong or driven by private interests.
A pime example of #motonormativity. The expectation that automobiles are different and need accommodation that we don't accept for any other private property.
Removing a bike lane during winter so people can store their private proprety on public space
#polmtl #velomtl #outremont #bikemtl #mtlpoli
@davewalker.bsky.social's drawing still resonates⤵️
bsky.app/profile/dave...
#polmtl #velomtl #outremont #bikemtl #mtlpoli
@davewalker.bsky.social's drawing still resonates⤵️
bsky.app/profile/dave...
November 21, 2025 at 2:00 PM
A pime example of #motonormativity. The expectation that automobiles are different and need accommodation that we don't accept for any other private property.
New incentives announced today in Ontario for ENERGY STAR appliances, including induction stoves and heat pump dryers.
November 19, 2025 at 6:13 PM
New incentives announced today in Ontario for ENERGY STAR appliances, including induction stoves and heat pump dryers.
Reposted by David Elfstrom 🍁
just learned we won an award for our blog post about Tom Holland and stormwater management.
remember, when you see an article about stormwater management, you repost it. i don’t make the rules.
remember, when you see an article about stormwater management, you repost it. i don’t make the rules.
What Tom Holland’s historic lip-sync showcase taught us about stormwater management
Grab your umbrella and your tights.
neorsd.medium.com
November 19, 2025 at 12:22 AM
just learned we won an award for our blog post about Tom Holland and stormwater management.
remember, when you see an article about stormwater management, you repost it. i don’t make the rules.
remember, when you see an article about stormwater management, you repost it. i don’t make the rules.
“The US is the only major country absent from Belém.”
More than 80 countries at Cop30 join call for roadmap to fossil fuel phase-out
Countries from Africa, Asia, Latin America, Pacific and Europe plead for transition to be central outcome of talks
www.theguardian.com
November 19, 2025 at 8:39 AM
“The US is the only major country absent from Belém.”
Cycling is easily twice as fast as riding a streetcar through downtown Toronto.
November 18, 2025 at 10:15 PM
Cycling is easily twice as fast as riding a streetcar through downtown Toronto.
If a worker is killed using manufacturing equipment, they don't just clean it up and get back to using it immediately. But that's what happens at road intersections.
Motonormativity is a dangerous disease.
Motonormativity is a dangerous disease.
what we should do now is of course close the intersection until it is redesigned. but we won't we will do nothing and wait for the next tragedy.
November 14, 2025 at 2:53 PM
If a worker is killed using manufacturing equipment, they don't just clean it up and get back to using it immediately. But that's what happens at road intersections.
Motonormativity is a dangerous disease.
Motonormativity is a dangerous disease.
Reposted by David Elfstrom 🍁
Researchers find that Germicidal Ultraviolet (GUV) airborne disinfection efficiency crashes above 50% RH for selected pathogens (both 222 nm and 254 nm). Could be important for the effectiveness of GUV systems in humid climates/season.
www.sciencedirect.com/science/arti...
www.sciencedirect.com/science/arti...
Quantitative evaluation of temperature and relative humidity effects on 222 nm UVGI air disinfection in a novel wind tunnel system
Airborne transmission is a significant pathway for pathogen spread, making air disinfection crucial for preventing infectious diseases. Ultraviolet Ge…
www.sciencedirect.com
November 14, 2025 at 1:24 PM
Researchers find that Germicidal Ultraviolet (GUV) airborne disinfection efficiency crashes above 50% RH for selected pathogens (both 222 nm and 254 nm). Could be important for the effectiveness of GUV systems in humid climates/season.
www.sciencedirect.com/science/arti...
www.sciencedirect.com/science/arti...
An excellent made-in-Canada choice for clean air. Highly recommended!
Quiet, 283 CFM CADR and drawing only 8 Watts of power.
Quiet, 283 CFM CADR and drawing only 8 Watts of power.
After some finagling to get the assembly procedure just right we are finally releasing the aluminum bodied POLARIS air purifier, made-in-Canada and based on the open-source design by Zack Deis.
1/3
#airpurifier #indoorairquality #covidisairborne
1/3
#airpurifier #indoorairquality #covidisairborne
November 14, 2025 at 12:08 AM
An excellent made-in-Canada choice for clean air. Highly recommended!
Quiet, 283 CFM CADR and drawing only 8 Watts of power.
Quiet, 283 CFM CADR and drawing only 8 Watts of power.
Reposted by David Elfstrom 🍁
Please enjoy my cartoon in today's Toronto Star
November 12, 2025 at 1:05 PM
Please enjoy my cartoon in today's Toronto Star
Reposted by David Elfstrom 🍁
This is literally the method they used for aerosol droplet sample collection.
November 11, 2025 at 12:55 AM
This is literally the method they used for aerosol droplet sample collection.
The deets in the ALT text 🥇
If Evidence Based Medicine has a poster child, it's the 2015 Antimicrobial Resistance and Infection Control study claiming N95s interfere with breathing in pregnant women.
Here's their setup, which they described as "simulating the actual wearing of an N95 respirator".
The RCT "gold standard" 🤣
Here's their setup, which they described as "simulating the actual wearing of an N95 respirator".
The RCT "gold standard" 🤣
November 11, 2025 at 12:34 AM
The deets in the ALT text 🥇
Reposted by David Elfstrom 🍁
Gas stoves emit methane, nitrogen dioxide and fine particulates at levels known to contribute to asthma and cardiovascular disease.
🧪 NEW STUDY: The annual indoor health cost of a single gas stove = $5,258
A big part this is from childhood asthma.
www.zmescience.com/medicine/gas...
🧪 NEW STUDY: The annual indoor health cost of a single gas stove = $5,258
A big part this is from childhood asthma.
www.zmescience.com/medicine/gas...
Gas Stoves Are Slowly Poisoning Homes and Cost Families Over 5,000 Dollars a Year in Hidden Health Effects
That "clean" gas stove? It's costing you a fortune in health.
www.zmescience.com
November 10, 2025 at 8:45 PM
Gas stoves emit methane, nitrogen dioxide and fine particulates at levels known to contribute to asthma and cardiovascular disease.
🧪 NEW STUDY: The annual indoor health cost of a single gas stove = $5,258
A big part this is from childhood asthma.
www.zmescience.com/medicine/gas...
🧪 NEW STUDY: The annual indoor health cost of a single gas stove = $5,258
A big part this is from childhood asthma.
www.zmescience.com/medicine/gas...
Here is the flight track for the aircraft in question. Note the ~250 knot speed because of its low altitude, about 6075 ft most of the flight, with 20 minutes at 10000 ft.
November 10, 2025 at 2:42 AM
Here is the flight track for the aircraft in question. Note the ~250 knot speed because of its low altitude, about 6075 ft most of the flight, with 20 minutes at 10000 ft.
"Great cycling cities do not use sharrows. The end."
“We never suggest using sharrows to create a bikeway,” Snyder concludes. “We’ve learned our lessons. Now that we know better, it’s time to do more.”
“We never suggest using sharrows to create a bikeway,” Snyder concludes. “We’ve learned our lessons. Now that we know better, it’s time to do more.”
Sharrows used to make sense in theory, but are now mostly useless and possibly dangerous.
momentummag.com/sharrows-use...
momentummag.com/sharrows-use...
Sharrows used to make sense in theory, but are now mostly useless and possibly dangerous
Road sharrows are about as effective as trying to protect yourself from a charging rhino with a wet paper towel
momentummag.com
November 9, 2025 at 3:26 PM
"Great cycling cities do not use sharrows. The end."
“We never suggest using sharrows to create a bikeway,” Snyder concludes. “We’ve learned our lessons. Now that we know better, it’s time to do more.”
“We never suggest using sharrows to create a bikeway,” Snyder concludes. “We’ve learned our lessons. Now that we know better, it’s time to do more.”
Reposted by David Elfstrom 🍁
@pipedreaming.bsky.social is one of the most esoterically interesting accounts I follow on here. If you are a nerd about buildings, you should follow
November 4, 2025 at 9:33 PM
@pipedreaming.bsky.social is one of the most esoterically interesting accounts I follow on here. If you are a nerd about buildings, you should follow
Reposted by David Elfstrom 🍁
Scare those viruses away - now proven by EPA! (Costume photo: Neil Comparetto)
November 1, 2023 at 2:20 AM
Scare those viruses away - now proven by EPA! (Costume photo: Neil Comparetto)
Reposted by David Elfstrom 🍁
We have ****ed the climate. Dressing this up as temporary overshoot is indefensible. But this does not mean we are doomed, & it certainly doesn't mean there is no point in trying to turn off the fossil fuel spigot. It's time to get real with climate risks.
www.technosphere.earth/derailment-w...
www.technosphere.earth/derailment-w...
Derailment warning as world faces threats to its ability to act on climate change
We may have seriously underestimated the risks of climate change. This includes derailment risks. This does not mean we are doomed, and it certainly does not mean there is no point in trying to turn o...
www.technosphere.earth
October 31, 2025 at 8:23 AM
We have ****ed the climate. Dressing this up as temporary overshoot is indefensible. But this does not mean we are doomed, & it certainly doesn't mean there is no point in trying to turn off the fossil fuel spigot. It's time to get real with climate risks.
www.technosphere.earth/derailment-w...
www.technosphere.earth/derailment-w...
Highly livable family apartment layouts that we need but unfortunately can't build in Canada or the U.S.
6 units with 16 bedrooms in a twinned point access block on ~75% of the floor plate area of this double loaded corridor w/ 9 units and 10 bedrooms. one of most compact i've ever seen
to get the same number of bedrooms in the double loaded corridor - it would have to grow by at least 2,400 sf
to get the same number of bedrooms in the double loaded corridor - it would have to grow by at least 2,400 sf
October 31, 2025 at 3:36 AM
Highly livable family apartment layouts that we need but unfortunately can't build in Canada or the U.S.
Building Science FTW! Why interzonal air flow matters in Multi-Unit Residential Buildings - presentation by Marianne Touchie of Cara Lozinsky's work. www.youtube.com/watch?v=8C-H...
Boots on the Ground: Why interzonal air flow matters in Passive House MURBS.
YouTube video by Passive Buildings Canada
www.youtube.com
October 22, 2025 at 10:28 PM
Building Science FTW! Why interzonal air flow matters in Multi-Unit Residential Buildings - presentation by Marianne Touchie of Cara Lozinsky's work. www.youtube.com/watch?v=8C-H...
