Temperature Control


HVAC systems [Heating, Ventilation, and Air-Conditioning] are responsible for 57% of residential energy consumption in select IEA developed countries, on average [excluding water heating – would add another 16%]. Improving temperature control could easily slash household energy consumption significantly, resulting in lower emissions and lower costs.

For reference, the average residential sector in the same IEA developed countries accounts for 20% of their final energy use – so we have the means to reduce a big chunk of our energy consumption. The environmental upside here is far too important to be ignored. We must adopt better solutions now and make them more affordable.

Note that residential energy consumption denotes both the electricity and natural gas consumption in a home. Heating is usually sourced with natural gas, while cooling typically consumes electricity. The cleanliness of the local electricity mix can determine whether electricity emits less or more GHGs than natural gas per unit of energy consumed.

There are essentially two categories of temperature control processes: preventive and reactive [we’ll see predictive/pre-emptive in the solutions].

Preventive Temperature Control

This refers to the ability of a house or building to withstand outside temperature changes. As external temperatures rise or drop for short periods of time, a house equipped with good preventive measures will see little to no variation in the internal temperature. This can significantly lower the need for reactive control.

Improving a house’s insulation is extremely important, although we have to make sure we’re using sustainable insulation materials. We’ll see in the solutions that there are many other things we can do to improve our preventive temperature control as well.

Reactive Temperature Control

This refers to the systems that can quickly modify space temperature, like HVAC systems, geothermal heat pumps, or solar thermal panels [the last 2 can be effective but are currently uncommon]. When a home has poor preventive control, its temperature will vary in sync with the external temperature, at which point an HVAC system usually turns on. Whether this is done automatically or with the press of a button, the problem stays the same: reactive temperature control is responsible for a massive share of our residential energy consumption. Consequently, better preventive temperature control is extremely important and is always the better investment long term.

Apartment buildings, company headquarters, and houses that have multiple floors and rooms also share the need for good ventilation – otherwise different rooms would have different temperatures [although that can be an advantage if certain rooms need to be kept cool/warm].

Houses are large heating and cooling energy consumers since they’re surrounded by a varying external temperature – so good preventive control is crucial for them.

Apartment units are usually much lower energy consumers than houses due to smaller air spaces per capita and shared HVAC equipment, but are perfect examples of how wasteful HVAC systems can be when poor preventive control is in place. Imagine two neighbors separated by a thin, large wall. This wall has extremely low temperature insulation.

Let’s imagine side A of the wall is kept at 18°C, while the other [side B] is maintained at 24°C. Due to crappy insulation, side A cools side B – and B heats A. How can these systems ever reach their stable final temperatures? They don’t [not for long at least], and meanwhile both the cooling from side A and the heating from side B of the apartment continuously draw considerable amounts of power [note that for houses, the other side of the wall would be outside – which partly explains why they’re such large HVAC energy consumers].

What’s the Future of HVAC and Its Energy Consumption?

In many developed countries, space heating energy consumption per area has decreased from 2000-2018. Unfortunately, that doesn’t mean space heating energy consumption has decreased, since there’s an increasing number of households. The major reasons for this decrease in energy intensity are better insulation systems, the migration of populations from hotter/colder climates to a more temperate climate year-round, the improved efficiency of HVAC systems, and a previously high baseline [i.e. space heating energy intensity was extremely high decades ago, so lowering it slightly isn’t much of an accomplishment].

On the other hand, developing countries are facing a considerable increase in power consumption. Warm countries like Mexico, Brazil, Indonesia, South Africa, and India each had under 17% of their households equipped with A/C systems in 2018– but have a combined population size of over 2 billion people. As these countries develop further, the percentage of households could rise toward that of developed countries like Japan [91% equipped]. That helps explains why A/C energy demand has tripled since 1990, and why it’s projected to triple again by 2050. Similar effects with heating could take place in colder regions of the world, but that’s less of a concern since cold countries are typically more developed and already equipped with heating systems.

Buying efficient HVAC systems is an easy way to decrease our HVAC power consumption. At an individual scale, the higher cost of efficient technologies would be offset in the following years with lower energy bills. Unfortunately, high-efficiency equipment won’t help us avoid the projected spike in A/C energy demand in developing countries – since there are just so many households to equip. Nonetheless, efficient technologies can help bring the 2050 projection of A/C energy demand down from 3 times the current energy demand to only 1.7 times.

Alas, it’s not always the right time to upgrade our HVAC systems. Slight efficiencies may not be worth replacing most of our current A/C units, as the life-cycle impacts from the new units need to be considered – especially at the individual scale. In that scenario, waiting for our old units to die before replacing them is likely the best thing to do.

The only sustainable solution is to reduce our HVAC demand at all scales. For governments, that will mean passing policies that incentivize individuals to improve their preventive temperature control. The right policies could allow people of any income level improve their home’s insulation, for example.

For individuals, that will mean changing the way we think about temperature, on top of improving preventive temperature control. Instead of just keeping temperatures at one setting year-round, we’ll need to cope with slight temperature variations in our homes [e.g. 18-26°C]. Otherwise, if we’re unable to adapt to slight weather variations, the world’s HVAC systems will continue to consume greater amounts of energy every year – which will increase our impacts on the environment. And that will worsen climate change, which will increase HVAC energy consumption during extreme climate events, and draw us into a vicious circle.


If we take a step back to see the whole picture, this looks very similar to a single-use vs. reuse situation. We could extensively limit the need for reactive control with better preventive equipment and techniques. Not only would that help lower our energy bills, it would also help decrease residential energy demand considerably. In turn, that would lead to less resource extraction, less GHG emissions, and less biodiversity loss.

P.S. –Fireplaces

Burning wood isn’t a great alternative to fossil-fueled heating systems. We’ve already covered why in Renewables when discussing energy production from biomass.