While some people turn up the heating during the cold winter months to make their homes warmer than in summer, others prefer to put on a warm sweater and woollen socks instead. Academician, Vice-Rector for Research, and Head of the Nearly Zero Energy Buildings Research Group, Jarek Kurnitski, belongs to the latter group. He shares his thoughts and experiences to encourage and inspire members of the university community to adopt more sustainable everyday habits. In January, the focus of the Sustainability Months is on heat and light – that is, buildings' energy.
What considerations guide how you manage heating, ventilation and lighting in your home across different seasons?
In general, everything runs automatically, although I do adjust the heating schedule once a year. From early March to the end of October, I use a lower heating curve. The impact is marginal, I do it mainly out of professional habit. Similarly, in summer, when cooling is needed, I have to manually select a lower supply air temperature on the ventilation control panel, as my seven-year-old system does not have an automatic function. Otherwise, everything runs like clockwork: the ground-source heat pump provides heating and cooling, and also shifts energy consumption according to electricity prices.
In the winter months, the indoor temperature in my home is very close to 21°C. In summer, cooling keeps the living room at 25°C, while temperatures in the bedrooms may rise to 26°C.
In a well-insulated house with high thermal mass, energy management is noticeable mainly when observing the heat pump. Its operation is not constant but alternates between higher-power preheating phases, while during periods of more expensive electricity only the circulation pump remains in operation.
The only thing I do not economise on is ventilation, which runs continuously at the same speed with a power demand of 90 W. I value good air quality and have a sensitive nose when it comes to odours from materials or textiles.
What motivates you to consider air quality in addition to indoor temperature?
Above all, the knowledge that sleep quality, work productivity and learning outcomes all depend on air quality. Ventilation is the very last thing on which to save energy. In work and learning environments, ensuring good air quality should be demand-based – that is, we ventilate for people, not for spaces. Such systems are already in operation in some of our lecture halls and should be implemented in the renovated U03 building and in all other buildings that will be renovated in the future.
Many people prefer to wear short sleeves indoors even in winter, while in summer they want to step into cooled spaces. How do you cope with changing temperatures?
Winter indoor temperatures are a paradox. Statistics show that symptoms and illnesses become more frequent when indoor temperatures exceed 22°C. An indoor temperature of 21°C is considered the best compromise between energy use, health and comfort in homes, and the general recommendation is indeed 21–22°C. Excessive cooling has the same effect as overheating – it can make your nose run. In Estonia, overheating in winter is quite common, for some reason, we are very fond of warmth. Central Europeans put on a sweater and manage just fine at 20°C or even below.
Share one good energy-saving tip for those who cannot adjust the indoor temperature in their homes.
In fact, indoor temperature should be adjustable in every home as room thermostats are generally available everywhere. In modern apartments, heating the supply air can be surprisingly energy-intensive, as it is often done using electricity. It is therefore worth checking the supply air temperature setting on the ventilation unit, which should be around 18°C or even slightly lower.
In addition to energy consumption, warmer supply air reduces the effectiveness of ventilation, as warm air remains near the ceiling and may not reach people. When it comes to household appliances, families with children may benefit from choosing a heat pump tumble dryer, which consumes significantly less electricity than conventional models.
Measure the sustainability of your lifestyle using the lifestyle test here.
Learn how to contribute to reducing your environmental footprint on the Sustainability Months page, in TalTech’s Green Guide, and in the Government Office’s Green Behaviour Toolkit (in Estonian).