T.REX: Thermal Regulation Experiment

Duration: June 15th - September 15th, 2019
Location: 3rd floor corridor and offices #322-326.

Goal: The goal of the experiment is to answer the following question:

Question: Can we effectively regulate the office temperature by regulating the amount of direct incoming sunshine and exchange of air with the outside?

Expected outcome: If we answer the main question affirmatively we will pursue the installation of heat reflecting blinds in our windows.

Methodology: We need your help with the experiment by observing the following rules.

  • Corridors:
    • Keep the odd numbered blinds and windows shut at all times.
    • Keep the even numbered blinds shut during the period 5:00-14:00.
    • Keep all windows closed during the period 9:00-23:59.
    • Do not prop the doors open to the back staircase or the main hallway.
  • Offices:
    • Keep the blinds shut during the period 13:00-22:00.
    • Keep the window closed during the period 9:00-23:59.

In case of bad weather or weather with outside temperature below 20°C you don't need to observe the above rules except for keeping the blinds that have installed thermal shield shut.

Petra & Petra will ventilate the rooms between 8:00-9:00.

We will monitor the temperature on the 3rd floor at several places and as a control we will monitor the temperature also on the 2nd floor.

Thank you for your cooperation!

Contact: Michal Koucky, <koucky@iuuk.mff.cuni.cz>

  • The sun power density is about 1 kW/m2 at Earth surface.
  • Our windows have glass area about 2m2.
  • Our heating elements have power output cca 1.5kW.
  • The idle power output of one PC is about 100W.
  • T. Rex lived approximately 68 to 66 million years ago.
Do the math!

  • Myth: - The second floor is cooler than the third. - BUSTED - Not supported by the measurements.

  • Myth: - Thermal foil on windows will help to stay cool. - Largely BUSTED - It's hard to discern any measurable effect except perhaps dampening of the temperature rise in the morning. Other factors seem to have bigger effect. Perhaps a better foil could help but it is not clear.

  • Myth: - People behave rationally. - BUSTED - Many people love to open their windows when there is 30°C inside and 35°C outside air temperature.

  • Conclusion: During the summer office temperatures were in the range 25-30°C, where all the offices follow the same temperature pattern while some offices stay hotter and some colder. There is no correlation between the position of the office and being hot/cold. The difference between the coldest and warmest offices is about 2°C. See picture below.

    Based on the temperature measurements, every single night between 1AM and 6AM the outside temperature drops to pleasant temperatures 20-25°C and below. There is a steep rise in the outside temperature after 6AM. Over each extended warm weather period, heat (delivered mostly by the direct sunlight) slowly accumulates in the offices with daily increase of the minimum office temperature by about 0.1-0.3°C. Opening windows between 1AM and 6AM would reverse the accumulation of the heat and could help to maintain a pleasant temperature in our offices throughout the whole summer provided people would behave rationally and would not open windows for the rest of the day.