Temperature Control


Heating, ventilation, and air-conditioning [HVAC] systems are responsible for 57% of residential energy consumption in select IEA developed countries, on average [excluding 16% for water heating]. For reference, the average residential sector in the same IEA developed countries accounts for 20% of their total final energy use. Improving temperature control has the potential to reduce energy consumption significantly, resulting in lower emissions and costs.

Note that residential energy consumption denotes both the electricity and natural gas consumption in a home. Currently, heating is often 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.

Preventive Temperature Control

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

To increase preventive temperature control, improving a living space’s insulation rating is often essential. Other ways to improve preventive control include painting a living space’s exterior to either reflect or absorb more sunlight, or planting trees that can block sunlight and wind once they’ve fully grown.

Reactive Temperature Control

Reactive temperature control is enabled by systems that can quickly modify space temperature, like HVAC systems, geothermal heat pumps, or solar thermal panels. Living spaces equipped with weak preventive control often rely on reactive control systems. Otherwise, space temperature would fluctuate as much as external temperature.

Unfortunately, reactive temperature control systems are massive energy consumers. Better preventive temperature control is therefore necessary to minimize the need for reactive control.

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.

Houses and Apartments

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 and shared HVAC equipment. The fact that apartment units share walls also reduces energy consumption, since there’s less contact with a varying external temperature.

The Future of HVAC

In many developed countries, energy consumption per area for space heating has decreased from 2000-2018. Unfortunately, that doesn’t mean energy consumption 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. it’s easy to decrease consumption if it was extremely high decades ago].

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 explains why A/C energy demand is projected to triple by 2050, although it’s already 3 times higher than in 1990. Similar effects with heating could take place in colder regions of the world, but those countries are typically already equipped with heating systems.

Reducing Energy Consumption

The most effective way to reduce HVAC energy consumption is by removing the need for HVAC in the first place. For governments, that will mean passing policies that incentivize individuals and businesses to improve their preventive temperature control. The right policies could allow individuals of any income level improve their home’s insulation, for example.

Another set of policies could facilitate the use of energy service contracts. These contracts help organizations with tight budgets lower their energy consumption. In these contracts, a company is allowed to plan, design, and finance an energy reduction project on behalf of the organization. In exchange, the company receives the costs savings resulting from the lower energy consumption for the next few years.

Governments could also improve policies to investigate alternative solutions to HVAC energy production. Implementing district heating and cooling systems in dense urban areas can be particularly effective when substituting fossil fuels for renewables and recovering heat.

For businesses and individuals, purchasing efficient HVAC systems is an easy way to decrease HVAC power consumption. Caution must be taken at the individual scale however, to ensure that the production impacts associated with this new technology don’t outweigh the benefits. 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.

On top of improving preventive and reactive control, individuals can also reduce energy demand through behavioral change. Instead of just keeping temperatures at one setting year-round, slight temperature variations in our homes [e.g. 17-27°C] could become the new ‘norm’.

Without these solutions, the world’s HVAC systems will continue to consume greater amounts of energy every year – which will increase GHG emissions. And that will worsen climate change, which will increase HVAC energy consumption during extreme climate events, and draw us into a vicious circle.


Better preventive control at all scales is essential to limit the need for reactive control. Implementing low-emission reactive control systems will then be necessary to reduce our impacts on the environment.

P.S. –Fireplaces

Burning wood often isn’t a great alternative to fossil-fueled heating systems. Check out Renewables for our summary on biomass.