Online educational resource on achieving indoor environmental quality with radiant based HVAC systems
Not for profit educational resource on indoor environmental quality.
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Radiant Floor Heating

Important message:

Consumers are upgrading HVAC systems to higher efficiency equipment and controls without understanding that often such new equipment when operated the old way, does not provide energy savings.

For example, a 98% efficient boiler only achieves such high performance when it operates at low temperatures typically below 80 deg F (27 deg C).

Regardless of the use of programmable thermostats, when a 98% efficient boiler is run at 180 deg F (82 deg C) it still only achieves a nominal 85%.

Likewise if people are relying on programmable thermostats for savings it’s important to know that a thermostat only tells the boiler that it "could" run but not at what temperature it "should" run at. This is not a trivial matter.

If you are upgrading to reduce your energy consumption, you have to look at the entire system – it’s not enough just to replace the equipment.

Learn how to operate your boiler for maximum efficiency.

Surprise, surprise

99% of all retail type thermostats only measure the air temperature - consider that in light of these two statements made 150 years apart...

From 1857:
"the Commissioners of the General Board of Health  advocated as one of the requirements for comfort that the walls of a room be at least as high in temperature as the general temperature of the room, while they included cold walls or floors amongst the conditions which make for discomfort.”

From 2010:
National Building Code of Canada v2010: Section A- Use of Thermal Insulation or Mechanical Systems for Environmental Control states, “In addition to controlling condensation, interior surface temperatures must be warm enough to avoid occupant discomfort due to excessive heat loss by radiation.”

Thermostats are supposed to be your ambassador to your HVAC system but they do a miserable job because  they don't sense what we sense.

...and this from the UK's Health and Safety Executive, “The most commonly used indicator of thermal comfort is air temperature – it is easy to use and most people can relate to it. But although it is an important indicator to take into account, air temperature alone is neither a valid nor an accurate indicator of thermal comfort or thermal stress.”

Learn more about this topic defined by the phrases: "mean radiant temperature" and "operative temperature"

Still the worlds most perfect thermostat (IMHO)...

The thermostatic radiator valve was invented over 70 years ago and its simplistic design is just as reliable today as it was back in the day.

A few features:

*It has no power
*Batteries not required
*Self powered
*Was the first wireless stat
*Is fully modulating
*Senses operative temp.
*One (1) page IOM manual
*Works like a door knob
*Turn right for less heat
*Turn left for more heat
*Incredibly reliable
*Anyone can work it
*Stocked everywhere
*Perfect for reduced:
 - manual dexterity
 - visual acuity
 - cognitive abilities

Perfect for grumpy designers and their clients who are sick and tired of technology stealing away valuable fishing time!

"The importance of individual temperature control in offices was established in the 1980s and 1990s. Unfortunately, the advantages of individual temperature control have not been realized well in practice, largely because of problems in the usability of thermostats." 
Sami Karjalainena, VTT Technical Research Centre of Finland

Here's the result of consumers not satisfied with "energy saving" claims from the NEST Learning Thermostat...


Plaintiff Justin Darisse ("Plaintiff') brings this action on behalf of himself and all others similarly situated against Nest Labs, Inc. Plaintiff makes the following allegations based upon information and belief, except as to the allegations specifically pertaining to himself, which are on personal knowledge.


1. This a class action against Defendant Nest Labs, Inc. ("Defendant") for using false misleading advertising, in website, print, and point-of sale promotional materials, as well as product packaging, to promote and sell the Nest Learning Thermostat ("Nest").

2. Nest is a wireless thermostat that can be remotely controlled from smartphones and tablets. In 2011, Defendant launched Nest, a sleek "new generation" thermostat that was supposed revolutionize thermostats, not unlike the iPod revolutionized music playing devices.1 But Defendant released a fancy, overpriced gadget (pictured below), which, while aesthetically "cool" like the iPod, fails at even the most basic function of a thermostat: accurately gauging and controlling temperature.

3. Defendant promises that Nest will provide energy and cost savings that Nest does provide. In fact, Nest increases energy use and costs because, contrary to Defendant's representation that Nest uses "multiple temperature sensors to determine the ambient temperature with a high degree of accuracy," customer reports and Defendant's own admissions show that Nest is so defective that it cannot correctly gauge ambient temperature.

4. Nest's base and faceplate heat up, which causes Nest's temperature reading to be from two to ten degrees higher than the actual ambient temperature in the surrounding room. This defect prevents the thermostat from working properly. As a result, Nest users do not experience the advertised energy savings.






Programmable Thermostats - Part I
Copyright (c) 2012, Robert Bean, R.E.T., P.L.(Eng.), and content contributors

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See: Programmable Thermostats - Part II (includes boiler efficiency )

A background discussion: room thermostats vs. the thermal sensors in your skin


"Only one out of four consumers program their set back thermostats"
source: Energy Information Administration; 1978, 1987, & 1997 Residential Energy Consumption Surveys, Ref. Decision Analysts, American Comfort Survey, 2000

"It has been a constant observation during our research that all common temperature controllers to date are quite impossible to use and understand correctly." source: R. Vastamaki, I. Sinkkonen, and C. Leinonen, “A behavioural model of temperature controller usage and energy saving,” Personal and Ubiquitous Computing, vol. 9, no. 4, pp. 250–259, 2005

"...thermostat usage was found to be weather dependent based on behavioral data from participants" source: Bernardoni, S., Curtis, M.,  Koliner, J., (2015). Engaging with a Thermostat: Using Seasonal and Connectivity-Based Differences in Residential Thermostat Use to Maximize Savings. WECC, Madison, Wisconsin



Suffice to say there is no shortage of debates about setback thermostats. We remain neutral since valid research supports their use in some applications. Our main issue with most thermostats is;

  1. they fail miserably to sense what the occupants sense in terms of thermal environmental indices.

  2. they are too complicated for most people.

  3. research shows users manually operating the devices regardless of their technological features.

Anyways, rather than perpetuate the debate amongst the real research and plethora of anecdotal energy savings claims, we thought we would present a different side that says, “just because a control could potentially reduce energy use, doesn't mean that it is operated in such a way that energy reductions are achieved.

No shortage of thermostats! Click to learn more about design.
Figure 1. A collage of programmable thermostats - it doesn't help users to have so many choice with so many options, it just creates "paralysis through analysis" - also most of them fail to completely sense what occupants sense.

The following is a list of scientific papers many which have studied how people actually use these devices with success and shockingly how they often end up using more energy than what they were intended to save.

Why? Because many people find them too complicated to operate so they are operated incorrectly.

We hope you find this useful, if so tell your friends and be sure to share your stories at our Linked In page where we have devoted an entire segment to Programmable Thermostats: In Search of the Holy Grail

Thermostat and Sensory Resources
A note on broken link: as much as we try to maintain links to third party sites, in the event of a broken link it will be necessary to search for the title using your browser.

1.   Andersen, R.V., Olesen, B.W., Toftum, J., Modelling Occupants’ Heating Set-Point Prefferences, Proceedings of Building Simulation 2011: 12th Conference of International Building Performance Simulation Association, Sydney, 14-16 November 2011

2.   Blankenburg M, Boekens H, Hechler T, Maier C, Krumova E, Scherens A, Magerl W, Aksu F, Zernikow B., Reference values for quantitative sensory testing in children and adolescents: developmental and gender differences of somatosensory perception, Pain, 2010 Apr;149(1):76-88. Epub 2010 Feb 6.

3.   de Groot, E., Spiekman, M., Opstelten, I., Dutch Research into User Behaviour in Relation to Energy Use of Residences, PLEA 2008 – 25th Conference on Passive and Low Energy Architecture, Dublin, 22nd to 24th October 2008

4.   Erlandson, T.M., Cena, K., de Dear, R., Gender differences and non-thermal factors in thermal comfort of office occupants in a hot-arid climate, Elsevier Ergonomics Book Series, Volume 3, 2005, Pages 263-268

5.   Gobio-Lamin, L., Usability of thermostat controls: an example of the UCL Energy Institute, Proceedings of Conference: People and Buildings, London, 2011

6.   Homework 1: Observing everyday user interfaces, Georgia Tech Sonification Lab , School of Psychology and the School of Interactive Computing

7.   Jacko, J.A., Human-computer Interaction: Interaction design and usability, 12th International Conference on Human-Computer Interaction, China, July 2007

8.   Karjalainen, S. 2007, Gender differences in thermal comfort and use of thermostats in everyday thermal environments, Building and Environment, Vol. 42, No. 4, pp. 1594-1603.

9.   Karjalainen, S., Koistinen, O., User problems with individual temperature control in offices, Building and Environment, Vol. 42, No. 8, pp. 2880–2887, 2007

10. Karjalainen, S., The characteristics of usable room temperature control, Ph.D. Dissertation, VTT Publications 662, ESPOO 2007

11. Karjalainen, S., Usability guidelines for room temperature controls, Intelligent Buildings International ,Vol. 2, Iss. 2, 2010

12. Karjalainen, S., Vastamäki, R., Occupants Have a False Idea of Comfortable Summer Season Temperatures, Proceedings of Clima 2007 Well Being Indoors

13. Karjalainen, S., Why It Is Difficult to Use a Simple Device: An Analysis of a Room Thermostat, VTT, 2007

14. Kempton, W., Feuermann, D., Mcgarity, A.E., Air Conditioner User Behavior in a Master-Metered Apartment Building,  Proceedings of the Fourth Symposium on Improving Building Systems in Hot and Humid Climates, Houston, TX, September 15-16, 1987

15. Kempton, W., Two Theories of Home Heat Control, Cognitive Science 10 I 75-90 (1986)

16. Larsen, T.S. et al, Occupants influence on the energy consumption of Danish domestic buildings – State of the Art, Aalborg University, Department of Civil Engineering Section for Architectural Engineering, December 2010

17. Malnick, T., N. Wilairat, J. Holmes, and L. Perry. 2012. Destined to Disappoint: Programmable Thermostat Savings Only as Good as the Assumptions about Their Operating Characteristics. ACEEE Summer Study on Energy Efficiency in Buildings.

18. Manning, M.M.; Swinton, M.C.; Szadkowski, F.; Gusdorf, J.; Ruest, K., The effects of thermostat set-back and set-up on seasonal energy consumption, surface temperatures and recovery times at the CCHT Twin House Facility, NRCC-48361, Institute for Research in Construction (IRC), National Research Council Canada, Ottawa, Ontario, 2007

19. Matos, R., Wang, K., Jensen, J.D., Jensen, T, Neuman, B., Svensson, P., Arendt-Nielsen L., Quantitative sensory testing in the trigeminal region: site and gender differences,  J Orofac Pain. 2011 Spring;25(2):161-9.

20. Meier, A.K., et al, How People Actually Use Thermostats, Lawrence Berkeley National Laboratory and University of California Davis, University of California Berkeley

21. Meier, Alan, Cecilia Aragon, Therese Peffer, Daniel Perry, Marco Pritoni. 2011. Usability of Residential Thermostats: Preliminary Investigations. Building and Environment. 46(2011)1891-8.

22. Nevius, M.J. and S. Pigg. 2000. Programmable thermostats that go berserk? Taking a social perspective on space heating in Wisconsin. Energy Center of Wisconsin. 

23. Norman, D.A.: The Design of Everyday Things. Basic Books, New York (1988)

24. Peffer, T., Pritoni, M., Meier, A., Aragon, C. and D. Perry, How people use thermostats in homes: A review, Building and Environment, 46, 2011

25. Peffer, T., Thermostat wars and other tales from the field, California Institute for Energy and Environment, Climate controls research group, Nov. 2012

26. Plourde, A., Programmable Thermostats as Means of Generating Energy Savings: Some Pros and Cons, University of Alberta School of Business, March 2003

27. Sachs, Olga, Verena Tiefenbeck, Caroline Duvier, Angela Qin, Kate Cheney, Craig Akers, and Kurt Roth. 2012. Field Evaluation of Programmable Thermostats. Final Report to the Building America Research Program. U.S. Department of Energy. Dec.

28. Shipworth, M., Firth, S.K., Gentry, M.I., Wright, A.J., Shipworth, D.T., Lomas, K.J., (2010) Central heating thermostat settings and timing: building demographics. Building Research and Information, 38 (1) 50 – 69

29. Tariku, F., Kumaran, M.K., Fazio, P., Thermostat setback effect in whole building performance, National Research Council, 2008

30. Urban, B., Gomez, C. 2013. A Case for Thermostat User Models. 13th Conference of International Building Performance Simulation Association, Chambéry, France, August 26-28

31. Vastamaki, R., Sinkkonen, I., Leinonen, C., “A behavioural model of temperature controller usage and energy saving,” Personal and Ubiquitous Computing, vol. 9, no. 4, pp. 250–259, 2005

32. Walker, I., Meier, A.K., Residential Thermostats: Comfort Controls in California Homes, Lawrence Berkeley National Laboratory, Berkeley, California, March 20088

33. Wall, S. and Healy, F. (2013). Usability testing of smarter heating controls. A report to the Department for Energy and Climate Change. Amberlight. DECC, London

34. Consumer Focus (2012). Consumers and domestic heating controls: a literature review. London: Consumer Focus.

35. Rubens, S., Knowles, J. (2013). What people want from their heating controls: a qualitative study. A report to the Department for Energy and Climate Change. Amberlight. DECC, London

36. NEST Class Action Lawsuit <>

37. Bernardoni, S., Curtis, M., Koliner, J., (2015). Engaging with a Thermostat: Using Seasonal and Connectivity-Based Differences in Residential Thermostat Use to Maximize Savings. WECC, Madison, Wisconsin


In case you haven't seen it all...Direct Energy presents "Energy Zombies: Thermostat Wars". This is one way to make light of the discomfort in peoples homes...evidently it's a big enough deal that it was worthy of a video from a distributor of energy services with over 6,000,000 customers.

For me it reaffirms just how barbaric some consumers must become as a result of the building industry ignoring the fundamentals of IEQ and standing upon built to code buildings and programmable thermostats as an acceptable benchmark in construction and energy efficiency.

Sweaters, cuddling and everyone agreeing on a single temperature from a single thermostat that doesn't represent what everyone is feeling...what marketing person from utopia wrote this video?

We love representative of families across the continent...what does it say about thermal comfort and control authority?

The use of "dummy" stats is universal which we would argue has ethical implications...we would love to hear your thoughts in our discussion group.

The Big Bang Theory - Sheldon & Leonard argument over the thermostat. A classic and to think the thermostat was part of the roommate agreement.

These women sharing their fights over the thermostat...wait for the part where a husband deliberately locked out the adjustment features...

If you Google search, "Thermostat Wars + youtube" you'll get about 11,500 results. If you Google search the phrase "Thermostat Wars" you get about 506,000 results. One would think that such a prolific problem would tell industry and consumers that thermostats make a poor proxy for comfort no matter how sophisticated the device. It should also tell you much society has been programmed to think that 72F (22C) air temperature is the exclusive proxy for comfort when it is only one of ten (1 of 10) metrics that must be considered when designing spaces. It should also tell you how the architectural industry has disconnected comfort from building performance when in fact they are intimately connected.

As we have noted for over 15 years, less than 3% of industry is aware of what thermal comfort is and of those that do, only 1.5% actually own ASHRAE Standard 55 Thermal Environmental Conditions for Human occupancy.

If you really want to understand thermal comfort and the role of architecture and building codes and budgets for HVAC system invest your time with the related reading materials below. It will open your eyes and give you a better feel for how you should approach your next project.

Related reading

Thermal Comfort: A Condition of Mind

Built to code: What does it mean for consumer thermal comfort?
Do I need an engineer? A Guide to Design Service Providers

HVAC does not equal IEQ
Where will your indoor climate system score?
How to "ball park" your budget for indoor climate control.
Indoor environments: Self assessment
The Total Comfort System - The "Un-minimum" System
Thermal Comfort: A 40 grit perspective for consumers
Do-It-Yourself HVAC - Should you do it?
The Cost of HVAC Systems - Are You Paying Too Much for Downgrades?
Radiant Installations - The Good, Bad and Ugly
Thermal Comfort Surveys - Post Occupancy, Part I
Thermal Comfort Surveys - Post Occupancy, Part II

Technical Essays

Programmable Thermostats - Part II (includes boiler efficiency )
Effectiveness coefficient, (Φ ) for temperatures in various countries

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