Energy efficiency in relation to HVAC

Energy efficiency has always been a relevant topic in the industry of ventilation, heating and cooling (HVAC). The difference today is that energy is an immediate question of supply, and consequently cost. In addition, global and local sustainability targets as well as requirements for a healthy, productive and comfortable indoor environments are key conditions for long-term tenants to stay and pay. This guide will give clear recommendations on how to achieve significant energy-savings from an existing HVAC-solution. It will also specify a number of critical questions that need to be answered in order to minimise the energy consumption from ventilation, heating and cooling when building new or renovating.

Ventilation, heating and cooling is not an isolated matter

Buildings in the western world stand for about 40% of the energy consumption, and energy related to ventilation, heating and cooling (HVAC) stands for 15%. Efforts should be made to reduce the energy dependency for HVAC, but it is essential to understand that ventilation, heating and cooling is part of a building, it cannot be singled out and tackled as a separate phenomenon.

As an example, the building envelope has a clear impact on energy-savings from ventilation, heating and cooling. Air-tightness, window characteristics and insulation needs to be considered when looking for reduced energy dependency. However, these factors may not necessarily be categorised as good or bad, they are rather parameters that influence on the alternatives for an energy-efficient HVAC-solution and a good indoor climate. In this context, it is important to understand that improvements made in one end can require an increased use of energy in the other end. For instance, a better insulated building envelope will give less temperature fluctuations inside, hence less requirements for heating and cooling but an increased demand for ventilation as the envelope is more air-tight than before.

Energy-savings and indoor environmental quality

Ventilation, heating and cooling (HVAC) cannot be separated from the indoor climate either. History taught us the relevance of a good indoor climate when airtight buildings and minimal ventilation caused several issues for buildings as well as people during the oil and economic crises of the 1970’s and 1980’s.

A lot has been learned since then in regards to building deterioration, sick building syndrome etc and today, it is known that ventilation, heating and cooling is needed for buildings, and people, to stay healthy. And not just that, several recent studies show that productivity and strategic thinking, comfort and health, as well as the ability to rest and recuperate is dependent on a good indoor climate. Having that said, we spend about 90% of our lives indoors, it is important to keep the history clear in mind and not chase just any energy-save but rather ensure long-term energy efficiency without compromising the indoor environmental quality (IEQ).

Learn more in our indoor climate guide

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How much energy can be saved?

In regards to possible savings, studies can give some indications of expected levels. First, by replacing older technologies for heating, using fossil fuels or simply electrical power, with for instance heat pumps, a significant energy-save of 50% or more is possible. Secondly, by using an air handling unit with a good heat exchanger which can recuperate the energy that is otherwise lost with the exhaust air, or ventilated out of the windows, an 80-90% save of the heating and cooling energy is viable. Last but not least, when utilising modern demand controlled ventilation systems it is possible to save up to 80% of the ventilation fan energy, and reduce the cooling and heating demand with up to 40%, compared to basic ventilation.

The above solutions are news to many standard builings, but even when such are in place, the potential savings can be substantial. A comparison between before and after the renovation of Katedralskolan, Sweden, showed that the installed new air handling units and demand controlled ventilation generated energy-savings of an impressive 70%. There are a great many similar buildings.

To learn more, see our reference case: Katedralskolan, Sweden

What can be done today with an existing HVAC-solution?

There are seemingly obvious situations when a solution for ventilation, heating and cooling (HVAC) may be updated or exchanged, designed more or less from square one. That is while renovating or when constructing new buildings. However, there is an opportunity to adjust, finetune or adapt the ventilation, heating and cooling without making time-consuming or costly renovations.

Modifications to suit current needs and requirements can deliver significant energy-savings already today. Tips and recommendations of how to go forward are made in this section of the guide.

To our recommendations

Many kinds of renovations

It is today known that about 75% of the building stock in Europe is energy-ineffficient, and it is absolutely impossible to describe the entire spectra of potential renovation projects where this can be improved. It is therefore crucial for every project to carefully design all buildings for minimal energy-dependency. The planned renovation process and the targeted improvements in terms of energy are both clear determinant factors of what alternatives are available to enhance the energy performance of a building's solution for ventilation, heating and cooling.

The type of renovation process that requires an entire building to be emptied will in this guide be discussed as a new-build project in the section below. This because the demands related to energy in those projects can be seen as almost starting from square one.

Learn more about energy-savings and renovations

System solutions to minimise energy consumption

It can be challening to start from a blank piece of paper, but it is actually a fantastic opportunity to optimise an entire solution for ventilation, heating and cooling (HVAC). It might sound over the top complicated, but as there are existing tailor made systems which connect key units and components – from room to rooftop – and ensure that their operation harmonise, it is not that problematic. It is rather a great potential to save energy on a long-term basis across all units in an entire HVAC-solution.

All about our optimisation systems

New-build or major renovation

Designing an energy efficient solution for ventilation, heating and cooling (HVAC) for a new building is really to start from a blank page, almost anything is possible. An extensive renovation project can be thought of in the same way, the building is completely empty and the design can start almost from square one. This latter type of renovation is expected to be very common already from the very near future. This is because building standards, regulations and legislations favour renovation and conservation of buildings to avoid to put additional strain on the environment by using further construction materials. To renovate is a perfect way to minimise the amount of embedded carbon in a building. However, an existing building structure can pose certain limitations in terms of space, and heritage-listed values are important to preserve. Most of this can usually be worked around, which again makes energy-efficiency and a good indoor climate of outmost priority.

With that said, the prerequisites and the requirements for the future are essential. They are fundamental to be able to narrow down the many alternatives of products and systems for an HVAC-solution that can deliver on both energy-efficiency and a good indoor climate. We have great experience from all phases of a construction process, both in regards to new-build and renovation projects - let us be of help.

3 things to know for long-term energy-efficiency

To be successful

Choose units for ventilation, heating and cooling which are energy-efficient in their own operation and which have the functionalitites that can answer to the needs and requirements of the indoor climate inside the building
Understand the difference between the systems for constant air volume (CAV), variable air volume (VAV) and demand controlled ventilation (DCV) and align room management system characteristics with the set requirements for energy-efficiency and indoor environmental quality
Select units and products with great flexibility and with possibilities to be updated or refurbished, this to be able to adjust the indoor climate to meet future needs and requirements, to make the building future-proof

Our Swegon ESBO software is developed to assist a project from the early stages to a complete building. It gives valuable information in regards to product specifications, indoor climate parameters and energy measures prior to the choice of units and systems in our product selection tools.

Read about CAV, VAV and DCV

Swegon ESBO for all project phases

Keep in mind not to chase just any energy-save, but rather ensure long-term energy efficiency without compromising IEQ.

Åsa Norén Lundh, Manager of the Indoor environment competence center at Swegon, on the topic of saving energy wisely without affecting the indoor climate.