August in New England can bring nights with very high humidity.

RH in orange; Black Globe interior temperature in Blue; Outside air temperature in green.

Excellent results overnight showing close agreement on temperature from both sensors, blue & green.

The temperature-humidity sensor is reporting higher temperatures and lower RH values than actual at the beginning and end of this chart, despite efforts to isolate & shield this sensor from sunlight, mount thermal conduction, and building heating effects. More work remains to craft a solar shield that enables accurate results 7x24.

Black Globe Sensor before being painted black. Temperature sensor mounted in the center of the ball.

6 inch copper ball resting on a roll of masking tape.

The Wet-bulb temperature is the temperature read by a thermometer that has its bulb wrapped in a distilled water-soaked fabric and ventilated. When air is at 100% relative humidity, the wet-bulb temperature is equal to the normal air temperature (dry-bulb temperature). As the relative humidity falls, the wet-bulb temperature becomes lower than the normal air temperature.

The Wet-Bulb Globe Temperature (WBGT) is a measure of heat stress in direct sunlight, which takes into account temperature, humidity, wind speed, sun angle, and cloud cover (solar radiation). Uniquely, the WBGT includes sunlight as part of the calculation. It is an important heat stress metric for human health safety and guide to managing workload while working or exercising in direct sunlight. The WBGT index was developed in 1957 as a basis for environmental heat stress monitoring to control heat casualties at military training camps.

The WBGT differs from the heat index, which ONLY takes into consideration temperature and humidity and is calculated for shady or interior areas.

This CDC report has a lot of detail that may be of interest especially if you have staff working outside during the summer.

The First Dog on the Moon provides a delightful overview of wet-bulb temperature.

Belgian authorities recently, on June 9th, mandated that hotels, restaurants, bars, event halls, and gyms must actively monitor carbon dioxide levels inside their venues. Carbon dioxide levels can be an effective measure for how well-ventilated a room is and by proxy, how much coronavirus may be present in the interior air.

A recent and excellent report by the UK government offers balanced insights into the conditions where CO2 monitoring can be effective and those where it may be less useful.

For example, “Measurements of elevated CO2 levels in indoor air are an effective method of identifying poor ventilation in multi-occupant spaces. In low occupancy or large volume spaces, a low level of CO2 cannot necessarily be used as an indicator that ventilation is sufficient to mitigate transmission risks (medium confidence).”

On the evening of June 30th, a fast-moving thunderstorm system moved through the area in approximately 30 minutes.

Overnight on July 2nd was a period of very heavy rain for much of the night.

Two heatwaves in June are unusual and unpleasant.

Lithium batteries require careful management of the temperature range for charging, with both minimum and maximum values for safety and battery life.

This module is located outside and exposed to the morning sun. It has a sun shield that is larger than the enclosure, and the unit is mounted on a plastic post to minimize heat conduction. The solar panel is mounted via an aluminum bracket to the top of the enclosure and may be an important source of heat conduction.

Prior to the heatwave, there was more than sufficient solar charging to maintain a 100% battery charge each day, shown in orange.

In the graph below, as the interior temperature, in black, rises above 95 degrees, charging is automatically disabled. For three Both mornings, the temperature is above 100 degrees by 10AM, leaving only a short charging window for the day.

Orange trace is the battery charge (%); turquoise step-trace shows the ambient light level, an un-calibrated sensor.

The heatwave was immediately followed by multiple rainy days with insufficient solar light to charge the battery.

A multi-spectral digital sensor is used to compare the spectral power distribution of two A15 800 lumen (60-watt equivalent) interior light bulbs.

The Osram is a conventional 2700K soft white bulb with a light output measurably weighted above 550nm, and objects reflecting this light are noticeably warm in tone.

The GE Refresh bulb fits in the category of daylight and provides greater luminance in the shorter wavelengths or cooler colors.

Output levels are relative to a full-spectrum white sensor on the same device just at the saturation level of 65000.

A dramatic increase in particulate matter.

A hair dyer used in a bathroom with the door open, and a particulate matter sensor located in another room on the same floor.

The chart illustrates how particle size distribution is weighted towards larger particles: PM10 (4 to 10 um) with the highest density and PM1.0 (0.3 to 1um) lowest, and that they remain suspended in the air for close to an hour.

20 minute sample period

For reference, the EPA National Ambient Air Quality Standards summary table can be found via this link.

Consistent discharge behavior with a distinct acceleration in rate-of-decline at the 70% charge mark.

The good news is a 4400mAh battery can power this outdoor module for three days if sunlight for solar recharge is limited during cloudy days.

4400mAh Battery voltage at 3.74V at end of graph

Over four days from a full charge

Lithium batteries do not like to be charged at temperatures below 32 degrees. A cold-weather function has been implemented with charging disabled when the enclosure interior temperature falls below 34 degrees. While initial data suggests this is working as intended, further testing is needed to verify charging current is not supplied to the battery.

Testing outdoors has demonstrated that solar heating of the enclosure is helpful in keeping the interior temperature above air temperature, extending the cold-weather charge window significantly. Good news for the winter, no doubt a sun shield will be needed during the summer.

Sometimes, when developing a completely new idea, a lot of testing is required to confirm system behavior and optimize.

At the Metropolitan Museum of Art.

Perhaps the most important tactic of the innovation process is to borrow and integrate concepts from an unrelated field.

This is a terrific example of borrowing from a distant field and organization to innovate and improve results in healthcare.

ASQ article can be found through this link.

From the original tweet with GIF animation:

A great example of borrowing innovation from one field for another. Doctors at a struggling children's hospital sent videos of their post-surgical hand-offs to Ferrari's F1 pit crew (see the GIF!) to improve. They reworked the process & reduced associated errors rates by 66%. 1/2 pic.twitter.com/kasmdezTmL

— Ethan Mollick (@emollick) October 15, 2020

Why was my basement dehumidifier still running in late October?

The summer of 2019 saw a high level of humidity sustained over four months, through the end of October!

2019 saw a large humidity range with average readings of 25% during the winter and nearly 55% over the summer, a delta of 30%, and a rapid rate-of-change from late winter to summer.

This year, 2020, the winter was not as dry with a low about 30% and a summer peak above 50%, but much of the time was spent closer to 45% for delta of 15%, half of the 2019 range!

This sensor is located on the first floor with the front door opening into this room which may explain some of the volatility in maximum daily RH values, the winter in particular.

Humidity varies by the hour, day, week, month, with a different pattern each summer.

To automate the task of emptying the basement dehumidifier water tank, I installed a digital liquid level sensor, lower right, to detect a full tank and trigger a relay to run a bilge pump located inside the tank for 90 seconds, outlet tube on left.

This could easily be converted to an IOT appliance. With this approach, we could measure and report the amount of water removed from the air over time. This may provide additional insight into controlling humidity, in addition to relative humidity and dewpoint data.

Excess heat from the compressor is vented through the cowling on the right and 4-inch dryer tubing to the outside keeping the basement cool and dry in the summer.

A highly simplified summary of the first stages of fermentation:

• During the first 3-15 hours after pitching the yeast, the aerobic phase, oxygen (added to the fermentor) is consumed by the yeast.

• When the O2 is exhausted, the anaerobic fermentation phase begins, and the yeast digests sugars to produce CO2 and alcohol.

The wort was poured into the fermentor and oxygen added from an external tank after lunch on the 6th. In the graph below we see the aerobic phase starting with an unexplained spike followed by a quiet period until the next afternoon where the transition to the anaerobic phase begins with the yeast rapidly consuming sugars and producing increasing levels of alcohol as detected by the TVOC sensor data shown in the green trace, and CO2 in blue.

TVOC Green; CO2 Blue.

This example shows data collected inside a closed single-car garage with a high ceiling and subject to wind-driven air infiltration. Approximately five gallons of wort was added to the fermentor with an external chiller for temperature regulation. The sensor module is located approximately 6 feet from the fermentor/chiller system.

For reference, the OSHA standard for the CO2 level a worker can be exposed to over an 8-hour day cannot exceed 5,000ppm (average). A short-term exposure limit is set at 15,000ppm, and at 30,000ppm alarms should be blaring and the building evacuated.

The project management profession continues to evolve as evidenced by an ever-increasing number of pages in each release of the PMBOK. The current 2017 version has 756 pages to digest.

The 7th Edition is due out next year, I don’t think more pages is the answer.

The decision by a project manager on the level of rigor and complexity for a project will have a significant impact on the likelihood of a positive outcome. Simpler is often better.

The 1977 amendments to the Clean Air Act called for daily analysis and reporting of air quality based on a uniform air quality index. The Air Quality Index (AQI) is EPA’s index for reporting air quality.

The higher the AQI value, the greater the level of air pollution, and the greater the health concern. For example, an AQI value of 50 or below represents good air quality, while an AQI value over 300 represents hazardous air quality. The AQI for PM2.5 is an average value based on 24-hour concentrations.

To create the AQI, raw sensor measurements are converted into a separate AQI value for each of five major pollutants (ground-level ozone, particle pollution, carbon monoxide, nitrogen dioxide, and sulfur dioxide). The highest of these AQI values are reported as the AQI value for that day, the primary pollutant. Each component is normalized to the same scale with a health threshold of 100. The AQI is not a composite metric.

For each pollutant, an AQI value of 100 generally corresponds to an ambient air concentration that equals the level of the short-term national ambient air quality standard for the protection of public health.

The chart below shows the relationship between the calculated PM2.5 AQI value and the particulate matter concentration measured in ug/m3:

Values above 250ug/m3 or an AQI value of 300 is considered hazardous.

Particulate Matter (PM): PM2.5 describes fine inhalable particles, with diameters that are generally 2.5 micrometers and smaller.

It is important to analyze and distill raw data into contextually meaningful information for rapid consumption by a wide range of stakeholders with varying roles and responsibilities.

Data visualization is most effective when an explanatory annotation layer is included.

Airtable provides abstracted views from a standard tabular spreadsheet format. These consolidated views enable users to organize, highlight, and share observations, issues, insights, challenges, and opportunities.

In the simple example embedded below, we use Airtable to organize a spreadsheet with multiple columns of information into a gallery or card view. Clicking on a card expands to show all information plus attachments that can be viewed directly. The cards are color coded based on priority(spreadsheet column), a built-in feature.

This model facilitates sharing across a community of stakeholders using a concise format where insights derived from data collection and analysis can be rapidly scanned, assessed, and acted on. The source spreadsheet(called a “base” in Airtable) and gallery are easy to keep up-to-date, and changes are dynamically updated to all active links shared to stakeholders! With Airtable, your organization has a automated record of data management initiatives, work underway, and results available 7x24.

The pandemic has impacted many aspects of our lives in ways that range from horribly tragic to annoying.

Interior spaces represent significant risk; density and duration must be managed.

Is there a practical indicator of potential risk arising from too many people in a space for too long?

A recent article in the New York Times brought to light a metric with a specific threshold as a potential guide as we navigate the short-term and long-term complications of a highly contagious virus. “If you have a carbon dioxide detector, you could try a technique previously used to manage the spread of tuberculosis, and use that to tip you off, Dr. Miller suggests. If CO₂ levels are above 1,000 parts per one million, you’d be wise to decrease the number of people in the indoor space, increase the amount of outdoor air or both, she says.”

Interior CO2 levels are a function of room volume, square footage + ceiling height, plus infiltration of outside air. Most organizations today are carefully managing how many people can be present in each space and limiting density and duration by reservation, appointment, or schedule.

Continuous monitoring of CO2 levels will provide an additional level of assurance that safety protocols are being followed, and issue an alert if levels exceed 1000ppm for a defined period of time(e.g. 5 minutes).