Wednesday, April 25, 2018

Ventilation Rate Success Story

We're just about to finish another semester of ENVR 119C - High Performance Buildings for Occupant Wellness at the Harvard Extension School. The class focuses on how the built environment impacts occupant wellbeing. Tomorrow (4/26/2018) we'll have Piers MacNaughton, ScD, Associate Director of the Healthy Buildings Program in the Center for Health and the Global Environment at the Harvard T.H. Chan School of Public Health. Dr. MacNaughton is one of the authors of the great CogFx studies that have shown a clear link between outdoor air ventilation rates and improved cognitive function in building occupants. Link:

Dr. MacNaughton's visit reminded me that when I was teaching this class last time, we had Dr. Jack Spengler come in to talk about their paper The Impact Of Green Buildings On Cognitive Function. Students were surprised to learn that even ventilation rates typically considered "safe" may be having a negative impact on cognitive function. Applying these lessons as part of his final project, Bryan Johnson evaluated ventilation rates at his wife's school in Arizona. She teaches 6 classes per day of 35 to 40 students. She had complained to the facilities department and to her husband that the room felt stuffy. Using the class project as an excuse to intervene, Bryan found the outdoor air damper position for the air handler serving her portion of the school was open to 25%. Bryan bought a Netatmo sensor to test CO2 concentrations (among other parameters) and found that CO2 levels were generally above 1,000 ppm during occupied hours, at times going as high as 1,350. He and his wife convinced the school to open the air dampers to 55% and found this brought typical CO2 concentrations to around 650 ppm. They then opened the dampers to 65% and got levels to about 600 ppm. The class has been operating for the past few weeks under these conditions and anecdotal evidence from teacher and students has been positive.

After class, Bryan emailed me with feedback from his wife. She received her year end district standardized final exam scores. Scores for all 6 of this year's classes were up compared to last year by an average of 5%. While the sample size is low and his work may not get published in any peer-reviewed journals, I wanted to share Bryan's results (with his permission) and applaud his effort. He was planning to approach the school with his findings and a series of additional recommendations including improving the lighting quality to more closely approximate natural sunlight thanks in large part to a great lecture from Dr. Lockley of Harvard Medical School's Sleep Institute. Nice work Bryan!

Friday, June 9, 2017

Monitoring-Based Commissioning (MBCx)

Shawmut Design and Construction recently delivered a monitoring-based commissioning (MBCx) program to one of our museum clients. The program by Panoramic Power uses clip on meters that take current readings every 10 seconds and sends them wirelessly to a local hub. Data is then sent off-site to their servers to be processed and displayed on a customizable dashboard. We're now able to remotely view the equipment and add rules to alert us if there are any opportunities for increased efficiency or indications of potential problems.

The images in this article show our work on some Multistack chillers. We’re monitoring all three phases of each of the three modular chillers in the museum. The image below shows the installed clip on sensors and the one above shows Chuck checking the amperage on his handheld meter to double-check the readings. A screenshot from the dashboard is included at the bottom, which shows how each of the three modules performed during the day. This information is available real-time and stored for long-term data analysis.

Once the sensors were installed and mapped, we added rules to alert us of any potential issues. We’re checking if any of the compressors are short cycling, if we’re not rotating through the three chillers to spread out the run time, if we have an overly high electricity draw from any one chiller, etc. The program is set up to automatically send a work order through the building’s computerized maintenance management system anytime an alert is triggered. We’re tracking chiller electricity consumption versus outside conditions and using the museum’s electricity tariff to show the cost to run the chillers on a daily, weekly, monthly basis. We are also monitoring the chilled water pumps, fluid coolers, and other components so we can a full picture of chiller plant efficiency and track the overall kW per ton. There are similar sensors on other equipment throughout the museum, from air handling units to computer room air conditioners.

Monitoring-based commissioning is now a very accessible technology. It is cost effective and can quickly pay for itself through energy savings. Clients not only save money, they also get increased reliability as MBCx allows for predictive maintenance to correct potential issues before they become a problem. Definitely something worth considering for complex buildings and anything with critical use equipment.

Tuesday, December 16, 2014

Site Surveying Toys

Chris evaluating site from above.
Last week I joined engineer Chris Rollins and University of Rwanda architecture student Christian "Kara" to do some surveying for a project in Kigali. Chris has done a lot of construction work throughout Africa and has been a great source of information for my UNICEF projects. The construction manual I've drafted is inspired by something similar he produced for projects in South Sudan. During this visit, we were able to play with a number of toys I don't usually have access to. Here's a quick summary with photos of the equipment.

We started off by marking a 10 meter by 10 meter grid pattern over the entire site with flags. Chris brought a Keson MP401E measuring wheel to get the distances, so no need to deal with standard tapes. A measuring wheel makes surveying a site much quicker and easier on the back. We used the same tool to measure distance to services (water, electric, paved road, etc.). It has a pause button on it, so when we'd run up on a large obstacle, we could pause it, move to the side, and restart to continue our reading. The handle folds down and Chris was able to fly with this and the other equipment. Chris is actually pictured in the Keson catalogue using one of these wheels for Engineers Without Borders in Malawi.

Chris using the measuring wheel.
Chris centering the bubble.
Once we had the grid laid out, we used a DeWALT DW090PK builders level to take elevations at each point. The builders level was set up at one of our grid points and all other points were measured compared to this point by having somebody stand at the point with the aluminum grade rod to get a reading. Chris will put the points as X, Y, Z coordinates into a spreadsheet, export as comma separated variable file, and import into AutoCAD Civil 3D and create a topographic map of the site, which will later be used to design the building, estimate cut and fill, etc.

Chris on the smart end, Kara holding the grade rod.

Kara trying his hand at the smart end of the level.

Kara about to drop the hammer.
Finally, to evaluate soil conditions, we used a Kessler K-100 dynamic soil penetrometer to get representative samples across the site. The DCP test uses an weighted hammer dropped from a set distance to pound a drive rod into the soil. Once you know the general soil type, the rate of rod penetration is entered into a computer and the CBR (California Bearing Ratio) value for the soil at different depths is given. CBR is a penetration test for evaluating the load bearing capacity of soils originally developed for road construction by the California Department of Transportation. Crushed California limestone is the reference value with a CBR of 100. Our site was getting values between 4 and 40 depending on where and how deep we were testing. These values will influence building foundation design and influence what type of construction can be built on site. This is the first time I've seen the DCP in use and I can think of many times when it would have been useful for one of my projects, especially those that have a lot of cut and fill (almost all projects in Rwanda, "Land of 1,000 Hills"). It would be good to sample un-disturbed soil and then compare that to the compacted backfill to make sure we get sufficient compaction to avoid settling and cracking concrete. The Kessler version we used even comes in a durable Pelican carrying case, perfect for flying around Africa.

Chris explaining the DCP.

Kara dropping hammer, Chris entering values into computer.

All of the survey data collected will be used to develop site plans for the client. Having accurate data means they'll know exactly what they're getting into if they choose to move forward. I've "surveyed" dozens of project in Rwanda, but this was the most thorough to date and had the best toys by far. Thanks Chris and Kara.

Monday, November 24, 2014

Making Gravel

In order to make concrete, first you need aggregate (gravel). At all of my projects in Rwanda, this means getting a delivery of large rocks and chipping away with a hammer until you get a pile of small rocks. They usually set the rocks on a circular pillow made of woven grass (the same pillows they use to carry stones on their heads). It is typically women and older men that get gravel duty, though this time there was also a younger man. This video is from a visit to the Mugombwa refugee camp on November 20, 2014. The aggregate will be used in construction of an early childhood development center (pre-school).

Wednesday, September 3, 2014

Site Clearing a Big Rock

Site clearing for the new Early Childhood Development & Family Centre in Mbuye Sector, Ruhango District (Rwanda). Unfortunately, there is a big rock in the top part of the site, much of which has to be removed. Very slow and strenuous work. Here's a video showing some of the effort. Not too much mechanical equipment (like jack hammers) in Rwanda.

Wednesday, August 6, 2014

Biking in Rwanda

Despite the challenges associated with biking in the "Land of 1000 Hills", bikes are still a very popular choice for commuting, catching a tax, and transporting goods. Here's a shot of some bikes parked while people attend a meeting during umaganda in Mbuye Sector, Ruhango District.

One way to get over the challenges of biking up steep hills with a single speed is to hitch a ride from a slow (relatively) moving truck, which everybody does. Of course, going downhill is relatively easy - dangerous, but easy.

Most ex-pats are comfortable riding on the dirt roads or foot paths (some of the best single-track in the world), but riding on the paved roads is not for the feint of heart as there is very little awareness of bikers by Rwandan drivers. I've seen a number of bloody (more than one fatal) accidents. The roads are narrow and people don't give bikers (or motos for that matter) room when passing. As Kigali increases from just over a million people to 2 million (2020 projection) and eventually 4 million (2040 projection) it would be great to find ways to encourage biking and make it safer and more convenient for those that do.

Thursday, July 17, 2014

RYACA "Dufashe Isi / Let's Save the World" Video

Here's a video on protecting the environment done by RYACA (Rwanda Youth Alliance for Climate Actions). I helped them prepare proposals / grant applications and reviewed the lyrics. Turned out great. Congratulations everybody, especially Landry Ndriko Mayigane, who really drove the project. Funding from US Embassy.