Let the sun shine in: lighting homes and warming pools with the sun

Plus: Unsustainable logging in the rainforest. The Colorado River flows again to its delta. Protection for a rare buckwheat, and more.

Solar Designs

Taking advantage of natural sunlight to light up our homes

The manner in which we think of renewable energy is shaped a lot by industry and marketing. We think of arrays of solar panels harvesting sunshine and windmill generating stations turning breezes into electricity.

But what of passive solar design? Simply letting the sun warm us and give us light in our homes, schools, and offices. How important might that be?

Researchers in South Africa investigated how much fossil fuel could be saved and how much carbon dioxide could be kept out of the atmosphere by simply designing a house to take advantage of daylight.

Common sense things like the orientation of the house and the size and number of windows are easy ways to brighten an interior.

Technological innovations also help, like automatic lighting controls that automatically dim when natural light illuminates a house interior. These controls can save a lot of electricity, from 20 to 92 percent.

Another benefit is that natural light is just more pleasant than artificial lighting. It enhances health and gives a sense of comfort, spaciousness, and security.

The researchers compared two houses in Alice, Eastern Cape Province, South Africa. Alice resembles a burg in the American Southwest, filled with low-slung buildings and wide streets. It sits about 60 miles from the coast and about 600 miles east of Cape Town.


The passive solar house was a prototype of an energy-efficient, low-cost, two-bedroom house that is part of the SolarWatt Park at the Alice campus of the University of Fort Hare. In addition to solar panels, the prototype house features passive heating and lighting. The control was a three-bedroom house built in the 1990s as part of a development.

Researchers measured the lighting in the living rooms of each house. They also set automatic lights to come on in each house when the natural light dipped below 200 lux during the day.

Lux is a measurement of illumination. An average home is illuminated to about 150 lux; supermarkets are illuminated to about 750 lux. An overcast day is about 1000, and full sunlight can be more than 107,500 lux.

The living room in the solar house had more interior light, averaging 194 lux from morning through evening, compared with the conventional house that averaged 55 lux for the same time period.

The solar house was designed so that the its living room, where residents are expected to spend the greater part of the day and evening, took advantage of sunlight, with windows facing north.(Remember, this is in the Southern Hemisphere.) The living room in the conventional house is on the southern side of the house, where natural lighting is minimal. As might be expected, the team confirmed that orientation made a big difference in the two designs.

On a daily average, the passive solar house required less electricity, saving 4.3 pounds of coal and keeping almost eight pounds of CO2 out of the atmosphere. That may not sound like much, but 1000 passive solar houses could save about 7847 tons of coal and 14600 tons of CO2 over ten years.

These findings were published in Frontiers in Energy Research on the 21st of May.

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Heating a pool and making hydrogen with the sun

In Iran an international group of scientists, from Saudi Arabia, Thailand, Kazakhstan, the U.S., and a number of other countries looked at heating a swimming pool with solar power.

The study was done on an indoor pool in Yazd, which is pretty much right in the center of Iran. Yazd enjoys about 300 sunny days a year, a pleasant and perfect place to heat a pool with the power of the sun. The pool is a little over 500 square feet, what you’d expect for an upscale family in the U.S. to have in their backyard.

The solar collector used by the research team was something between high tech and low tech. Water flows inside black tubes that are surrounded by clear vacuum tubes to maximize heat absorption and minimize heat dissipation. The researchers, unfortunately, did not give dimensions on the size of this solar collector, but wrote that it “has the capacity to heat between 500 and 700 L of water each day, and is able to increase the water temperature at a rate of 7°C/h.”

The researchers estimated that over the 20-year life of the solar collector, greenhouse gas emissions could be reduced by 142 tons of CO2. There would also be corresponding reductions in particulate and other pollution, and other environmental degradation from fossil fuel use.

The results of the study were published in Frontiers in Energy Research on the 19th of May.

I’m not sure how or why the researchers also investigated hydrogen production from solar power, but they did. A 3.5’ x 5’ solar panel with a 20 percent efficiency rating can produce almost five pounds of hydrogen in a year. That’s about the energy in five and a half gallons of gasoline. I bet you didn’t know that.

Other News

Brief synopses of important environmental happenings. Click the links for more information.

Sustainable forest management is not sustainable

“Sustainable” forest management has been touted for decades as an answer to clearcutting destruction of forests. It has also been promoted as a means of economic development while maintaining rainforests and biodiversity.

But a new study sponsored by the Rainforest Foundation UK has found that selective logging, thought to be sustainable, actually leads to deforestation in the Congo.

Researchers looked at 60 areas that were logged and compared them to eight control areas. They found a “cascade of deforestation” 10 to 15 years after logging operations, as logging roads open up areas for settlements or other human uses. (Rainforest Foundation UK)

Colorado River flows all the way to its mouth again

So much water is drawn from the Colorado River that in recent years it has dried up before reaching its destination in the Sea of Cortez. But early last month, as part of an agreement between Mexico and the United States, water began flowing through the Colorado River’s delta.

The renewed flow is intended to resemble the Colorado’s natural spring flow, reaching its highest flow in early June and continuing through early October. Restoration of riparian and the delta’s natural ecosystems are primary goals of the program. (Audubon Society)

Seven killed in Bangladeshi power plant demonstration

This is in the “why didn’t I see this in the New York Times” department. Although it is only tangentially an environmental story, I wanted to include it because of its importance.

Police fired upon demonstrators at the under-construction Banshkhali Coal Power Plant in April, killing seven and wounding dozens more. The demonstrators were workers and villagers who were demanding better working conditions, payment of unpaid wages, and reduced working hours during Ramadan.

Banshkhali is a coastal region of southeast Bangladesh. Police fired after an altercation flared. Previous clashes led to the deaths of four individuals in 2016 and one person in 2017. (Friends of the Earth Asia Pacific)

Cozy relationship between EU Commission and natural gas industry

Since 2014, when the EU Commission first disclosed lobbying meetings, senior EU officials have held 813 meetings with natural gas companies and their industry associates. That’s about two meetings a week. Meetings have continued even during the pandemic: 131 since January 2020. In that time, how many meetings did the Commission have with renewable energy representatives? (Global Witness)

Endangered species status sought for a rare buckwheat

In response to a proposed lithium mine in Nevada, the Center For Biological Diversity has petitioned and litigated the U.S. Fish and Wildlife Service to give endangered species status to the rare Tiehm’s buckwheat.

The entire habitat of the buckwheat is only about ten acres. The mine, which is proposed by the Australian mining company Ioneer, would destroy 60 percent of the buckwheat’s habitat in phase one of its operation and 80 to 90 percent of its habitat in phase two.

The Fish and Wildlife Service is considering protection and initiating a 12-month finding of the plant. (Center For Biological Diversity)

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