This simple and smart solution could solve cities’ extreme heat problem

This simple and smart solution could solve cities’ extreme heat problem


In the MENA region, where shading, because of the prevailing climate, has been for millennia and still is one of the most important architectural elements for all built structures of the past, this simple and smart solution could solve cities’ extreme heat problem exposure.

The above-featured image is for illustration and is credit to TENSILE FABRIC SHADE


This simple and smart solution could solve cities’ extreme heat problem

Gensler spent three years researching how to mitigate extreme heat in vulnerable communities.
[Photo: courtesy Gensler]

Three years ago, the community impact team at the global design, architecture and planning firm Gensler set out to find answers to a question that rises to the very top of every architect’s mind when a heat wave sweeps over a city: What is the fastest, cheapest way to cool down our cities? Or as Amanda Stone, Gensler’s research manager and community impact specialist, put it: “How can we design a design process to create solutions for the built environment that would combat extreme heat?”

The answer Gensler came up with—an adaptable shading structure that can be configured to fit different kinds of public spaces—is by no means a silver bullet that will help cool cities everywhere in the world. But it is worth dwelling on the process that informed it, which could (and should) become a blueprint for any designer or urban planner working with local communities.

This simple and smart solution could solve cities’ extreme heat problem
[Image: courtesy Gensler]

After receiving three internal research grants to more deeply explore the question, the Gensler team got to work, but it found that answering Stone’s original prompt—which puts an emphasis on the process, not the output—was too broad and complex to come from only one team. And so, it was circulated across Gensler’s broader network of designers and researchers, who then tapped into their own networks in search of community partners who may want to participate.

One of those communities was in the Costa Rican city of Curridabat, which has been suffering the consequences of climate change for years. Paula Badilla, sustainability specialist at Gensler’s Costa Rica office and regional resilience leader for Latin America, explains that Curridabat already had a strong climate action plan and had been measuring things like its heat vulnerability index, urban heat island effects and flood risk across the municipality. But the team didn’t simply rely on those datapoints to inform the design process—they actually asked residents where they felt the hottest.

This simple and smart solution could solve cities’ extreme heat problem
[Photo: courtesy Gensler]

Perhaps unsurprisingly, the heat maps and residents’ responses didn’t always match, so in Curridabat, the community chose the final three locations based on their own experiences of the city: right outside a human development center, close to a sports field, and in a skatepark with one lone tree.

[Photo: courtesy Gensler]

In those three locations, the team developed a brief for a shading structure, which they turned into an internal competition to design what it would look like. More than 80 people participated across Gensler’s Latin American offices. The winning design ticked all the boxes: it was modular and could therefore be accommodated to fit all tree locations; it was easy enough for the community to build it (and feel a sense of ownership in the process); and it could be made with pretty much any locally found materials—in this case bamboo, rope and canvas. As a bonus, it could also provide more than just shade: residents could use the canvas as a projection screen, or replace it altogether with art, or a trellis for ivy.,c_limit,q_auto:best,f_webm/wp-cms/uploads/2023/09/i-1-90947083-costa-rica-heat.gif

[Image: courtesy Gensler]

To measure the impact the structure will have on the community and how they experience heat, the team is planning to install humidity and temperature trackers on all three structures, then will monitor them over the next three months. They’re also hoping to install CCTV-like cameras to understand who is using the structures (children? teens? parents?) and what they’re using them for. They could, of course, survey residents in a few months, but as project manager Ana Thomas notes: “When you ask people, they tell you things you want to hear, but we need the right information about how they really feel.”

Either way, the findings will not only inform future iterations, but also serve as validation for the community. “The one good thing that I have seen in terms of what really works is knowledge sharing,” says Stone. “It’s gathering the data, gathering the best practices, and sharing those with community members, not keeping it insular.”

Not able to prevent climate breakdown without impacting the living world

Not able to prevent climate breakdown without impacting the living world


The authors elaborate on how at this stage, we are not able to prevent climate breakdown without impacting the living world.  Would what is put forward be applicable to the MENA region? Or is it a No longer Climate Change but an Environmental breakdown forever?


The above-featured image is for illustration and is credit coverdrone


Why we won’t be able to prevent climate breakdown without changing our relationship to the rest of the living world

Not only is deforestation unsightly. Fewer trees also mean less precious carbon sinks to absorb anthropogenic greenhouse gas emissions.
Flickr, CC BY-SA

Christian de Perthuis, Université Paris Dauphine – PSL and Édouard Civel, Université Paris Dauphine – PSL

Because of its growing impact on society, global warming has taken centre stage in the public debate. While most of us have not read the reports by the Intergovernmental Panel on Climate Change (IPCC), heat waves, intensifying storms and the multiplication of extreme events remind us of the scale of climate disruption and the urgency of action.

Despite being documented by the Intergovernmental Sciences Policy Platform on Biodiversity and Ecosystem Services (IPBES), the equivalent of the IPCC for biodiversity, we know little about how biodiversity erosion might affect us and the rest of the planet. Its links and interactions with climate change are underestimated, and any policy to address either in isolation will miss the mark. It’s impossible to take effective action against global warming without addressing our impact on the rest of the living world, and vice versa.

Fossil carbon, living carbon

IPCC scientists have been explaining since their first assessment report (1990) that climate change is a stock problem. To halt global warming, it is not enough to slash greenhouse gas emissions. We need to stabilise their stock in the atmosphere. To achieve reach net zero we must reduce emissions – the inflow into the stock – to the level of the outflow, which is made up of CO2 absorption by carbon sinks (forests and oceans) and the elimination of non-CO2 greenhouse gases at the end of their life cycle.

This requires that we adopt a two-pronged plan, aimed both at cutting down our reliance on both fossil and living carbon. The former feeds the vast majority of the world’s pollution, with coal, oil and natural gas accounting for 70% of the world’s greenhouse gas emissions. Tackling it will require that we take on the so-called energy transition.

On the other hand, a quarter of greenhouse gas emissions come from “living carbon”, mainly as a result of specific agricultural emissions (unrelated to fossil fuel use) and tropical deforestation and other land use changes that erode carbon sinks. There is no way to achieve carbon neutrality without a profound transformation in the use of living resources, to ensure the reflux of agricultural emissions and better protection of carbon sinks. This is the challenge of what we might call the agroclimatic transition.

One of the major difficulties of the ecological transition is to carry out these two transformations simultaneously, as they involve distinct economic mechanisms. For fossil carbon, we need to introduce scarcity by reducing the use of coal, oil and natural gas to the absolute minimum. For living carbon, we need to reinvest in the diversity of ecosystems to reduce agricultural emissions and protect carbon sinks as part of a bioeconomy.

From adding to subtracting

Since the start of the Industrial Revolution, energy transitions have followed one another. They have all involved adding new energy sources to a system initially based on the use of biomass. The result has been a massive increase in the amount of energy used worldwide.

The climate is forcing us to break with this logic. Lowering emissions is not a matter of adding decarbonised sources to the energy system. It’s about removing fossil fuels. We need to switch from a logic of addition to one of subtraction.

Russian tractor in a field in Ethiopia

Deforestation and agriculture are the source of ‘living’ carbon emissions.
Ifpri/Flickr, CC BY-SA

From an economic viewpoint, this means massively reconverting brown assets linked to the production or use of fossil fuels, through a double movement of investment in green and disinvestment in brown. The heaviest cost for the economic system is not the hundreds of billions invested in wind or solar farms, battery gigafactories or hydrogen electrolysers. It’s the cost of disinvestment that forces us to downgrade or reconvert brown assets: financial assets, of course, but also physical assets and, above all, the human assets on which the energy transition depends.

Multiple instruments will have to be called upon to bring about such a transformation. Pricing carbon from fossil fuel use is a key way to reflect the increasing scarcity of the atmospheric capacity to store carbon. Whether obtained through taxation or emission trading schemes, such taxation raises the cost of using fossil fuels, without returning the resulting rents to producers, as happens, for example, when oil prices soar on energy markets. On the demand side, it is a powerful stimulus to energy efficiency and sufficiency; on the supply side, it encourages a shift away from carbon assets.

The main difficulty with fossil carbon taxation lies in controlling its distributive impact. As the “gilets jaunes” protests in France showed, fossil carbon taxation without redistribution to the most vulnerable poses more problems than it solves. Only a redistributive carbon tax will be socially acceptable. Similarly, if carbon pricing is to be extended on an international scale, the proceeds must be returned on a massive scale to the countries of the South.

The distributional impacts of regulated carbon markets should also not be underestimated. Within the European Union, the extension of the emission trading scheme to the transport and buildings sector will increase household energy bills. This is why the proceeds from allowances sales at auction must be redistributed to the most vulnerable households via a “social fund” which will be the pillar of the regulation to be put in place.

Yellow vests’ protest in Paris in January 2019  Wikimedia, CC BY-SA


While fossil carbon taxation accelerates the energy transition, negative carbon taxes – in other words, fossil fuel subsidies – delay it. Following the outbreak of war in Ukraine, these subsidies reached unprecedented levels in the European Union, with the multiplication of “tariff shields” erected as a matter of urgency to protect Europeans from the worst of the cost of living crisis.

Another pernicious form of subsidy to fossil fuels is the free allocation of CO2 allowances in the European trading scheme, which hampers the emergence of a green industry, a lever for the competitiveness of tomorrow’s Europe.

Investing in the diversity of living beings

Let’s imagine for a moment that the world has eradicated all use of fossil fuels in 2050. Would we automatically be in a situation of climate neutrality? Everything depends on what has been achieved on the second front of the transition, that of living carbon, the source of a quarter of the world’s greenhouse gas emissions.

Pricing fossil carbon is hardly useful for the agroclimatic transition. Worse, it could even prove counterproductive: using a CO2 price based on energy criteria, it would become profitable to transform the Amazon rainforest (or the centuries-old oaks of the French Tronçay forest) into short rotation coppice to produce energy! The reason is simple. Agro-climatic transformation means finding ways to reinvest in biological diversity, in other words, in the abundance of living things. But the price of CO2 does not reflect the value of this diversity. We therefore need to use other instruments, which are more complex to implement.

On land, forests are the main carbon sink. Their capacity to soak up atmospheric CO2 is weakened by a combination of climatic and anthropogenic factors. In France, for example, the CO2 storage capacity of forests has been divided by three since 2005, mainly due to climatic factors. There is therefore an urgent need to adapt forest management methods in anticipation of the severity of tomorrow’s climates. Worldwide, the main anthropogenic impact on forests is tropical deforestation. Its main cause is the expansion of land for crops and livestock. This is why the key to halting deforestation lies in changing agricultural practices.

The key issues of agriculture and food

The impact of farming systems on the net balance of greenhouse gas emissions is not limited to deforestation. Depending on the techniques used, farming systems may themselves release carbon into the atmosphere (deep ploughing, draining of wet soils, etc.) or, on the contrary, store it in living soils (conservation agriculture, agroforestry, etc.). The former erode biodiversity by specialising farmers according to industrial-type logics. The latter use living diversity to intensify production and regenerate the natural environment.

These agroecological techniques also make it possible to better withstand tougher climatic conditions, while reducing methane and nitrous oxide emissions from agricultural sources. In economic terms, their promotion requires investment in innovation, research and development, the establishment of dedicated farm advisory networks and, above all, incentivisation to reward farmers for the ecosystem services they provide to society. This is not something that happens spontaneously on the market. It requires public intervention and dedicated funding.

As in the case of energy, the agroclimatic transition implies, on the demand side, that we consume smarter and less. The foods we eat have contrasting climate footprints. There can be no successful agroclimatic transition without finding ways to dramatically reduce emissions associated with the most polluting ingredients, including industrially processed foods and animal products, especially those from ruminant breeding. The use of food rations might be one way of achieving this, according to the recommendations of the world’s health authorities.

Remembering the ocean

Last but not least, the agroclimatic transition will have to take into account the management of the oceans and marine biodiversity, which are currently the blind spots of climate policies. Global warming and certain human practices (overfishing, pollutant runoff, etc.) are altering marine biodiversity, a crucial component in the storage of CO2 by the oceans. Protecting the ocean sink is vital to stabilise tomorrow’s climate: it is estimated that the continental biosphere contains four times more carbon than the atmosphere. For the oceans, it’s 47 times.

The authors thank Frank Convery for his insightful review

The Climate Economics Chair of Paris Dauphine-PSL University is organising, in partnership with the Toulouse School of Economics and the National Museum of Natural History, the 24th Global Conference on Environmental Taxation, which will take place from September 6 to 8, 2023 and will have as its theme “Climate & Biodiversity: Tackling global footprints”.


Christian de Perthuis, Professeur d’économie, fondateur de la chaire « Économie du climat », Université Paris Dauphine – PSL and Édouard Civel, Chercheur au Square Research Center et à la Chaire Economie du Climat, Université Paris Dauphine – PSL

This article is republished from The Conversation under a Creative Commons license. Read the original article.




How MENA’s economic and climate crises add fuel to wildfires

How MENA’s economic and climate crises add fuel to wildfires

Arid climates, deforestation, and urbanisation have each aggravated the risk of wildfires in the MENA region. Countries have scrambled to find strategies to mitigate this, however, without resources, they remain at the mercy of the climate crisis.

Researchers said that July 2023 would be the hottest month on Earth in history. According to the World Meteorological Organization, the global average temperature for July was 16.95 °C, exceeding the previous record set in 2019 by a third of a degree Celsius.

In the Arab region, temperatures soared to unprecedented levels with Egypt and Algeria experiencing temperatures exceeding 45 °C, while some cities in Iraq recorded temperatures close to boiling point.

The world has experienced intense heatwaves in the past six weeks, which led to numerous forest fires in various countries, including those in the Middle East and North Africa region. Countries such as Morocco, Tunisia, Algeria, Palestine, Syria, and Lebanon have suffered casualties and significant losses in vegetation and animal life due to these fires.

“Drought is a perfect condition for fires. It is not the only reason for wildfires in the MENA region however as human activities such as deforestation and burning rubbish or agricultural waste close to the forest also cause wildfires”

Perfect conditions

The eastern Mediterranean countries of Lebanon, Syria, Turkey, and Palestine, as well as the northwest African countries of Algeria and Morocco, are among the most vulnerable to wildfires in the MENA region.

It is anticipated that heatwaves can have negative effects on wildfires in the MENA region. A simple explanation is that vegetation can dry out during unusual heat events, making it more flammable. Excessive evaporation of soil moisture during these prolonged heat events also stresses vegetation and makes it more prone to fire, according to Ahmed Kenawy, professor of climatology at Mansoura University, Egypt.

Ahmed told The New Arab that some of the common plant species in the region’s drier areas, particularly those that have adapted to the dry climate, contain oils and resins that can be very combustible, especially during heat waves. However, depending on the prevailing weather conditions, these effects can vary greatly from one region to another.

Hotter temperatures dries out crops and increases the risk of wildfires [Getty Images]

Professor Ahmed Kenawy also pointed out that increased humidity during these heat events may reduce the likelihood of wildfires in coastal areas.

Lower humidity accelerates the drying process of vegetation and decreases the moisture level of lifeless organic matter, such as leaves, twigs, and grass, which makes them more prone to burning in interior regions. In certain parts of North Africa, like Egypt, local hot winds, such as the Khamisin, can rapidly spread wildfires, particularly in late spring.

Hesham Eissa, an environmental expert, told The New Arab that winds can rapidly spread wildfires, making them difficult to contain and control.

Also, human activities in the extreme heat during heatwaves may lead to increased use of fire-related activities, such as outdoor cooking or burning waste, which can inadvertently spark wildfires.

Hesham explained that climate change is also affecting wildfires by releasing greenhouse gases into the atmosphere, further exacerbating global warming. “This, in turn, can lead to more frequent and intense heat waves, creating a vicious cycle that increases the risk of wildfires in the region.”

Regional struggle

Morocco is one of the countries in the region most affected by forest fires, and the authorities used Canadair (amphibious) planes to extinguish the fires while evacuating the residents of the areas near this forest. The temperature was recorded at 50.4 degrees Celsius in the city of Agadir, in the centre of the country.

At the end of last July, the National Agency for Water and Forests in Morocco announced that the number of fires registered from the beginning of January to the date of July 24, 2023, amounted to 222, in which the fires swept 10,000 square meters. Forests cover 12 percent of the country.

Since the start of this summer, numerous fires have erupted in various regions of Algeria, with the most intense one hitting the northeast of the country, causing the death of 34 individuals, including ten soldiers, in late July. Additionally, the Algerian authorities have disclosed that the fires that affected multiple states last month resulted in the damage of 11,500 people, 972 buildings, and 24,000 hectares of land.

In Libya, the National Center of Meteorology announced last week that temperatures had risen, touching 49 degrees Celsius in some internal areas. At the same time, fires continued to break out, causing no deaths or injuries, but palm trees were damaged in different parts of the country.

The same dangers extended to Tunisia, which witnessed the outbreak of seven fires that spread to some populated areas as well as the destruction of large areas of agricultural crops close to the Gall ranges. Fires of varying size and strength also broke out in Lebanon and Palestine.

In Syria, the high temperatures caused fires to break out in agricultural and forested areas, especially on the Syrian coast, which witnessed widespread damage. The largest fires were in the countryside of Latakia Governorate, which lasted for five consecutive days in the coastal forest areas and required the intervention of Russian helicopters, along with Syrian ones, to extinguish them.

Professor Ahmed Kenawy believes that wildfires are common in these countries because of the typical Mediterranean climate: wet winters and dry, hot summers. “Symbolic cedar trees, for instance, are a common target of forest fires in Lebanon. The 2010 Carmel forest fire in Palestine was one of the deadliest in the country’s history. Importantly, the high rates of urbanization in these countries, especially in close proximity to forested areas, raise the danger of forest fires, especially those started by humans.”

Mitigation is a must

Theresa Wong, a geographer and Climate Change Officer in the FAO Regional Office for the Near East and North Africa, said that the region is highly vulnerable to climate change and that the climate is expected to be hotter and drier in the future. “Drought is a perfect condition for fires. It is not the only reason for wildfires in the region however as human activities such as deforestation and burning rubbish or agricultural waste close to the forest also cause wildfires.”

She explained to The New Arab that wildfires have significant environmental impacts, affecting various ecosystems and natural processes. Some of the major environmental impacts of wildfires include loss of biodiversity, soil degradation, maintaining the water cycle, and air pollution. It also makes the livelihoods of people who rely on these forests difficult.

Wong mentioned that the FAO supported the creation of a regional network on forests and wildland fires (Near East Network on Wildlands Forest Fire, NENFIRE). “We supported countries to have a fire management plan, such as Morocco, Lebanon, and Algeria. It is important for countries to include fire mitigation processes in their national strategies to combat climate change.”

The professor of climatology affirmed that since wildfires know no international boundaries, fighting them may be more effective if done at the regional level. “In the affected regions, it is also crucial to establish buffer zones between wilderness and populated areas. Community participation in fire prevention efforts is also encouraged through volunteer fire departments.

Mohammed El-Said is the Science Editor at Daily News Egypt. His work has appeared in Science Magazine, Nature Middle East, Scientific American Arabic Edition, SciDev and other prominent regional and international media outlets. Follow on Twitter: @MOHAMMED2SAID

Read more on The New Arab

Kuwait to be uninhabitable in the next few decades

Kuwait to be uninhabitable in the next few decades


Kuwait to be uninhabitable in the next few decades: Report

Experts say Kuwait needs to push renewable energy transition

By Ali Hamza in Kuwait Times

KUWAIT: As Kuwait experiences a faster rise in average temperatures compared to the global average, numerous reports suggest that many parts of the country will become uninhabitable in the coming decades. According to the Environment Public Authority, certain areas of Kuwait could experience temperature increases of up to 4.5 degrees Celsius above the historical average, rendering large portions of the country unsuitable for human habitation. Additionally, according to statistics from Our World Data, Kuwait ranks third in the world for electricity consumption per capita, with a staggering 19,433 kWh per person.

This high electricity demand is primarily met through fossil fuels in power plants, contributing significantly to carbon emissions. Kuwait also faces a substantial water consumption rate, with 61 percent of its water produced through energy-intensive desalination processes, releasing greenhouse gases into the atmosphere. These gases, acting as greenhouse gases, trap heat from the sun, exacerbating the temperature rise. Kuwait’s economy heavily relies on the oil sector, which involves the burning of fossil fuels and further contributes to greenhouse gas emissions.

In 2021, Kuwait’s per capita CO2 emissions reached 22.49 tons, making it one of the countries with the highest carbon emissions per capita. Consequently, Kuwait currently ranks as one of the most polluted countries globally, ranking seventh for air quality. Addressing the impending environmental disaster in Kuwait requires concerted efforts and innovative solutions. While the country heavily depends on oil and gas production, reducing greenhouse gas emissions is essential. Technologies like Direct Air Capture (DAC) offer the ability to capture CO2 directly from the atmosphere, regardless of location, for storage or other uses.

Given the substantial greenhouse gas emissions from the oil and gas industry, adopting Carbon Capture and Storage (CCS) technology to capture CO2 emissions from industrial processes and power plants can help mitigate emissions while allowing continued hydrocarbon production. Kuwait’s significant reliance on desalination for fresh drinking water poses another challenge. To reduce greenhouse gas emissions associated with desalination, Kuwait can transition to more renewable energy sources, such as solar thermal desalination.

Kuwait’s flat and open terrain provides an ideal setting for wind power generation. Installing wind turbines strategically can harness wind energy and convert it into electricity. Moreover, investments in large-scale solar panels can lead to hybrid electricity systems, combining multiple renewable energy sources like wind and solar with energy storage systems for a more stable energy supply. Promoting electric-powered vehicles, such as electric buses and installing charging stations in parking lots, can further reduce carbon emissions.

Several companies have already initiated projects to promote renewable energy sources in Kuwait. For example, KOC’s Sidrah 500 project is a large-scale photovoltaic solar energy initiative with the capacity to generate 10 MW of electric power from solar energy. This project is expected to save 500,000 barrels of oil over 20 years, equivalent to planting 500,000 trees.

Numerous other renewable energy projects are in development in Kuwait, with the Shagaya solar power project aiming to generate approximately 3.2 GW of electricity from renewable sources by 2030. “Kuwait possesses significant potential for large-scale renewable energy production, but it has a long road ahead,” said Sameer Ahmad, an environmental supervisor at Dietsmann Technology, emphasizing the need for sustained efforts and progress in this direction.




A future without air conditioning is becoming harder to imagine


A future without air conditioning is becoming harder to imagine where AC (Air Conditioning) is now seen as essential – but the more we use it, the more we help heat the planet.

The above-featured image is for illustration and credit to MANARA magazine.

By Michael Marks July 19, 2023 in

At this moment in Texas, it is difficult to imagine living without air conditioning. Most parts of the state are stuck in a streak of triple-digit temperatures with no end in sight. AC is, literally, a lifesaver. And the number of people worldwide who use it is expected to grow, especially in places like China and India.

There’s a contradiction inherent in air conditioning, though: The more we use it, the more we help heat the planet. Climate watchers like Stan Cox have long called to wean ourselves off AC, or at least reduce our reliance on it. Cox is a fellow at The Land Institute and the author of “Losing Our Cool: Uncomfortable Truths About Our Air-Conditioned World (and Finding New Ways to Get Through the Summer).” 

Cox spoke to the Texas Standard about whether a future with less air conditioning is still possible.

This transcript has been edited lightly for clarity:

Texas Standard: To what extent does air conditioning itself contribute to global warming?

Stan Cox: Air conditioning kicks off kind of a vicious cycle in which our greenhouse gas emissions make summers become warmer, so we use more air conditioning. And then by burning more energy for air conditioning and the refrigerants from air conditioning, which are greenhouse gases, we’re guaranteeing that future summers will be even hotter.

Is air conditioning here to stay, or do you see a time in which we we might actually be able to do without it?

Unfortunately, it probably is. Back 15 years ago when I wrote this book about air conditioning, I argued that certainly we need it for heat emergencies, but that the routine lavish use of air conditioning and commercial spaces and houses is excessive, and especially in this country. But it’s getting harder and harder each year to make that argument.


What technologies or techniques do you have in mind to make better use so that there’s not this sort of profligate use of AC? 

It’s really going to take an overhaul of our built environment: to tear up parking lots, tear up streets, make it hard to drive in urban areas, but to plant trees and grass there, to plant green roofs on buildings and to adjust our selves to the temperature. Because when we’re in continuous air conditioning, it lowers our heat tolerance. Being exposed to warmer temperatures actually makes us more tolerant of higher temperature.

We’ve become over the past 60 years people not worrying about not being in that optimum temperature range in the 70s to a place where now it’s considered a necessity. People for millennia have gotten by in hot climates without air conditioning, so it’s not like we can’t do it. Although if we keep emitting greenhouse gases the way we are and we keep seeing temperatures rise so fast, then, you know, there’s not much you can do about it.


Let me ask you about something that I think a lot of folks who work days think about as they leave their house in the summer. Do you turn off all of your AC, come home to a house that’s rather hot, then crank up your AC to try to get it back to not as hot as it has been? Or is it a more efficient use of energy and perhaps more environmentally sound to bring the temperature up in your house and then bring it back down when you get home, or just leave it at one constant temperature all the time?

With central air conditioning in a large house, certainly the idea of leaving the air conditioning off all day on a really hot day and then coming home and turning it on is going to use a lot of electricity. And I’m not an expert in these things, but probably having the thermostat automatically switch between daytime and nighttime settings.

In most countries other than the U.S., central air conditioning is not really all that common. There will be what are called split ACs that are in certain rooms of the house, and they are turned on only when the space is occupied and only during times when it’s uncomfortable. In that case it will very quickly cool that one room down and then only have to keep a much smaller volume of air cool.