Cooling Imperative – Headed for the Rocks

In my previous articles (August 2020, Nov/Dec 2022, Jan 2023 and June 2023 GSEF Newsletters), I wrote about market growth in cooling (air-conditioners, central A/C systems due to rising ambient temperatures, particularly in Asia and Africa. A recent article (and its online discussion) made very interesting viewpoints.? In this article, I will concentrate on its human elements.

Today, in many smaller and emerging nations in Asia and Africa, it is a challenge for their utilities to serve growing residential/retail cooling loads (human comfort) with their existing T&D network. In larger or more developed nations, it is an issue of equitable allocation of cheap green-energy between communities (human comfort) and large data center cooling loads (clamoring for cheap green energy).

In a January 6, 2024 article by Rhea Mogul and Aishwayra Iyer on CNN.com titled Extreme heat is pushing India to the brink of ‘survivability.’ One obvious solution is also a big part of the problem (msn.com). The article touches on a few critical elements (paraphrased below):

1.?????? By 2050, India will be among the first places where temperatures will cross survivability limits and within that time frame, the demand for air conditioners (A/C) in the country is expected to rise nine-fold, outpacing all other appliances (per IEA).

2.????? Vast swathes of India’s population (particularly urban) are beginning to rely on A/C for their physical and mental wellbeing. The country’s more-tropical southern regions remain hot year-round. Over the past five decades, the country has experienced more than 700 heat wave events. In June 2023, temperatures in some parts of the country?soared to 47 °C. Poor people are borrowing money to buy cheap used air-conditioners.

3.?????? India’s electricity cooling consumption increased 21% between 2019 and 2022 (per IEA). ?By 2050, India’s total electricity demand from residential air conditioners will exceed electricity consumption of all of Africa. This predicament encapsulates the paradox – “The hotter and wealthier India gets, more Indians will use A/C. The more they use A/C, the hotter the country will become”.

4.?????? Prof. Radhika Khosla of Oxford University notes, “Cooling is now on the global agenda, but the hard work must begin to ensure everyone can stay cool without further heating the planet.” Planting trees to absorb sunlight, water bodies, courtyards that promote cooling and clever ventilation are among the more sustainable “passive cooling strategies”.

I posted the above article on LinkedIn (over 2,500 views) and got interesting feedback. Prof. Andrew Swingler, University of Prince Edward Island (PEI), Canada (an old acquaintance), responded by saying “human cooling is going to get critical for survival”. His rationale is paraphrased below:

1.?????? “I'm not sure what to make of these passive cooling suggestions. When it's too hot to survive, it will be simply, too hot to survive.? Humans need to dissipate about 100W (2,250 calories per day) to stay cool. That's relatively easy when the ambient temperature is lower than our body temperature. But when the wet bulb temperature exceeds 35C (i.e. 100% humidity at 35C or 75% humidity at 40C) the ambient conditions are not survivable without actively cooling the body. You die. Shade or no shade”.

2.?????? If 100W of direct body cooling is all people need to survive (plus a 100W of food - see the connection?) and if we're worried about actively supplying this cooling energy from primary energy sources - I encourage all OECD or developed country residents - well at least us North Americans- to realize that we are, ourselves, blazing though about 10,000W (10kJ/sec) or 100 times our food intake energy to live now.

3.?????? We don't need to cool entire rooms. It can be done efficiently. Solar PV is often correlated with hot places. Humans can drink cooling fluids, wear cooling scarves. Ice is also a reliable and low-cost energy storage for cooling. Keeping people cool to live with 100W of cooling power is not and should not be part of the problem.

According to Singapore’s national climate study, Southeast Asia is expected to get 2.5°C– 6°C warmer during the three hottest months (March to May) by end-century. When high humidity is added to the mix, these projections could prove dangerous. For the first time, the projections is based on wet-bulb globe temperature (WBGT), which is more holistic than air temperature. Human bodies shed excess heat primarily through evaporation (sweat), which becomes less effective when humidity and air temperature are high. Between 2018 and 2022, there were 8 days of high heat stress (WBGT exceeding 33°C). The government has mandated to give hourly breaks during such times.

Myanmar, Thailand and Laos shattered all-time records in 2023 when temperatures climbed upwards of 43°C in places and reached 45.3°C in Thailand. High heat stress days is projected to increase sixfold by mid-century for South/Southeast Asia and could be year-round by end-century. A separate report by the World Bank, relates much of South/Southeast Asia to hotter climates and potential impact to agriculture and water. India had more than 700 heat wave events in the past 50 years. In June 2023, temperatures in some parts of the country soared to 47 °C.

I have been associated with a few retrofit A/C technology developments that are commercially available. While most are inexpensive (payback of less than 3 years), their take-up lags in the developing world largely due to landlord-tenant-service manager segregated accountabilities. If the goal is to allow that daily 100W per capita cooling needed then critical policies and their strict enforcement alone will lead to smart solutions, ultimately driving down costs through mass adoption. Seeking voluntary abandonment of old A/C units will not work.

In my view the following strategies must be pursued in parallel to achieve quick results:

1.?????? Retrofit compressor-cycle optimizers on older “Dx” units. These insert into the thermostat circuit (not power circuit) and control the compressor cycle to enable efficient performance. The energy savings is about 25%.

2.?????? Retrofit “token passing” controllers in large campuses (having multiple central and small units), to enable each A/C unit to wait and take its turn. These individual unit pre-programmed wait times (up to 10 minutes) does not increase space temperatures dramatically. This allows for campus A/C electricity demand to be capped.

3.?????? Retrofit demand-controlled A/C and ventilation systems in large buildings and malls using occupancy, CO2, CO, humidity, temperature sensors. ?Most buildings are designed with fixed air changes per hour. Smart wireless sensors are available that enable this solution.

4.?????? Manufacture textiles that enable efficient cooling of the body (small battery/fuel-cell sources) thus avoiding requirement to cool the entire room (or house or office). Today, USB-charged miniature fans are incorporated into tourist caps. Such solutions will reduce about 60-70 % of total space cooling requirements in residential, commercial and office environments.

5.?????? Improve the M-Cycle evaporative cooling technology (an old acquaintance) that is a low power alternative to the A/C compressor technology. The operative issues are (a) need for lots of pure scarce water; (b) biofouling of cooling pads; and (c) decreasing its form factor.

In closing, repeated talk of an escalating cooling crisis does not solve anything. Human comfort and wellbeing are a basic right, and governments globally must ensure policies and subsidies to secure such remedies that solve this crisis. Climate change is not a quick turn around issue and hence, the need for practical interventions. This is not a huge ask relative to the human crisis waiting to unfold. The cooling imperative certainly appears headed for the rocks !