Quantifying increased efficiency achievable by improving indoor climate

Quantifying increased efficiency achievable by improving indoor climate

In this module, you will be guided through the calculation that shows the effect and the value of improved indoor climate where the air temperature is optimised by reducing temperatures above 24°C and increasing temperatures below 20°C.


A hydronic, or radiant, cooling or heating system uses water as the cooling medium instead of air, and this potentially offers many advantages.

For example, the better the indoor climate in a building, the higher the user satisfaction and the better the working efficiency will be.
To gain an understanding of the link between indoor climate, satisfaction and working performance, this module will present a value calculation that quantifies the value of increased staff working performance related to the air temperature in an office environment.
The actual value calculations are based on numbers from the REHVA Guidebook no. 6. “Indoor climate and Productivity in Offices”.

Research has shown, that if air temperatures above 24˚C is reduced by just 1˚C, the working performance will improve by roughly 1.5% and if air temperatures below 20˚C is increased by 1˚C, the working performance is improved by roughly 2%.

Let’s look into how we can calculate the savings. First, we look into savings by decreasing temperature over 24˚C by 2˚C.

Firstly, we must calculate the total cost of the affected time. We do that by entering the number hours per day that temperature exceeds 24˚C.

Multiplying that by your business days per year and the number of employees we get the total annual number of hours affected.

This we multiply with the total salary per hour, which is the average monthly salary for per employee divided by the average monthly working hours.

Now we have the total annual salary cost in the affected time.

And as we decrease the temperature by 2˚C we must multiply the efficiency gain, which is 1.5%, by 2. Now we have the total annual salary saving caused by reducing the temperature by 2°C.

Now let’s look into the savings by increasing temperature below 20˚C by 2˚C. Well, the math is nearly the same except that we of course need to start with the number of hours per day that temperature is below 20˚C. And the gain in efficiency is slightly higher so we can now multiply the cost by two times 2% to obtain the total annual savings.

You can calculate your own savings by using the interactive pdf that you can download from the page where you found this online training.

Page 2 handles the cases where temperature exceeds 24˚C. You just fill in the affected hours per day, the number of business days per year, the average monthly salary of your staff, the average monthly work hours and how many employees you have. And the savings will automatically be calculated for you on the fly.

Page 3 deals with temperature below 20˚C and works in a similar fashion.
When done you can of course save the pdf to your computer for sharing the result with your colleagues.