Wouter van Marken LichtenbeltDept. Human Biology!

To comfort or not to comfort!

Healthy Buildings!Eindhoven"May 18-20, 2015"

3!

Energy Balance"

!!Living outside "thermoneutralzone"

  Current models"

  Temperature and health: acclimatization"  Cold acclimation, energy expenditure, insulin sensitivity, comfort"

  Heat acclimation, energy expenditure, comfort"

  Interaction with other senses"  Light"

  Implications for modeling"

4

Outline"

  Comfort"  Comfortable conditions satisfy optimal human condition

in natural environment (e.g. energy savings)"

  Drives human (thermal) behavior"

  Health"  Slight discomfort"

  Increase resilience to uncomfortable conditions "

  Increase energy metabolism"

"

5

Comfort and health: conflicting?"

  Food"

  Physical activity"

  (Thermal) environment"

6

Comfort and health"

  Based on the physics of heat transfer."  Limited inclusion of human physiology."  Limited validity on individual level."  Valid in steady state situations."

  Has led to tightly controlled indoor temperatures with minor seasonal and daily fluctuations."

Built environmentconventional model (Fanger)"

Fanger, Danish Techn Press 1970!

Adaptive comfort model"

Outdoor temperature (°C)"

Indo

or te

mpe

ratu

re (°

C)"

28""""22""""16"

5 10 15 20 25 30 35!

Conventional model"

Adaptive model"

Humphreys et al., Energy and Buildings 2007; De Dear et al., Energy and Buildings 2001!

Include health!

  Energy metabolism"

  Glucose and lipid metabolism"

  Cardiovascular"

  Resilience to cold and heat (winter/summer mortality)"

  Include thermal physiology"

  Include individual variation (body composition; acclimatization)"

  Include specific groups"  Obese; elderly; females"

"

9

Suggested model improvements" Thermoregulation"

Heat loss " " " ""

Thermoneutral zone"

ambient temperature"

heat

pro

duct

ion"

28 32 °C"

Comfort zone!

Thermoneutral zone in humans"

mild cold"

van Marken Lichtenbelt and Kingma 2013!

Metabolic Research Unit Maastricht (MRUM) Energy expenditure/Thermoregulation:Indirect calorimetryWireless thermometry"Skin blood flow"

Maastricht Respiration Chambers"!

shivering Skeletal muscle

Non-shivering Brown fat

Van Ooijen et al. Br J Nutr 2005!

Mild cold: nonshivering thermogenesis! Short term (3 hour) mild cold (15°C) exposure"

Van Ooijen et al. Physiol & Behav 2004!

NST up to 30 % of RMR Large individual variation""

4.4!

4.5!

4.6!

4.7!

4.8!

4.9!

5!

5.1!

5.2!

5.3!

5.4!

1! 2! 3! 4!

EE (k

J/m

in)!

time (h)!

-5!0!5!

10!15!20!25!30!

1! 2! 3! 4! 5! 6! 7! 8! 9! 10! 11! 12! 13! 14! 15! 16! 17! 18! 19! 20!

NST (%)!

Thermo-neutral!

--------- Mild cold ----------!

Brown fat – White fat!

Combining metabolic studies and PET/CT scans"

19

  24 male subjects (age:18-32 y; BMI 21-39 kg/m2)"  Thermoneutral 1h (22°C); mild cold 2h (16°C)"

20

Thermoneutral! Mild cold!

Brown fat activityThermoneutral versus cold"

Van Marken Lichtenbelt et al., NEJM 2009!

Brown Fat activity inversely related to body fat"

Van Marken Lichtenbelt et al., NEJM 2009!Vijgen et al. PlosONE 2011!

  Brown adipose (BAT) tissue in adults"

  BAT activity is related to thermogenesis"

  BAT is blunted or absent compared to lean young adults(in line with results on thermogenesis) in:"  obese"  elderly"  type2 diabetes"

22

Summary"

23

(mild) cold acclimation" Cold acclimation experiment"in lean young adults"

  9 females; 8 males"  10 day cold exposure"  6 h/d"  14-15 °C"

Van der Lans,JCI 2013!

25

Cold acclimatization"

before! after!

Van der Lans, 2013!

Increase in energy expenditure (NST)Increase brown fatNo gender differences"

*! *!

Van der Lans et al. JCI 2013!

Cold acclimatization"

Cold acclimation experiment"in diabetes type 2"

  8 male patients T2D (age 59.3±5.8 y, BMI 29.8±3.2 kg/m2)"  10 day cold exposure"  6 h/d"  14-15 °C"  hyperinsulinemic-euglycemic clamp "

Hanssen et al., Nature Med accepted! 28!

Thermal comfort increase after cold acclimation(10 day, 6 h/d, 15 °C)"

comfortable"

just comfortable"

just uncomfortable"

uncomfortable"

before" after"

Van der Lans et al. JCI 2013!Hanssen et al. Nature Med!

29

Summary cold acclimation"

Increase brown adipose tissue and energy expenditure in healthy lean young subjects"

Significant increases insulin sensitivity in type2 diabetes"

Increase thermal comfort ""

30

Heat acclimation"

To study thermoregulatory behavior and thermo-physiology before and after mild heat acclimation""

"- 22 lean subjects""- 7 day heat acclimation (.5 h/d; 33°C)""- behavior assessment and thermoneutral zone " ""

Pallubinsky et al.!

Thermoneutral zone in humans"

Schellen et al. in prep. !

∆T = 10 °C/h!

A

15 20 25 30 35 400.5

1.0

1.5

2.0

very uncomfortable

uncomfortable

just uncomfortablejust comfortable

comfortable

very comfortable

TNZwarmTNZcool

thermal comfort TNZwarmthermal comfort TNZcold

Temperature in ˚C

Rel

ativ

e en

ergy

exp

endi

ture

B

15 20 25 30 35 400.5

1.0

1.5

2.0

very uncomfortable

uncomfortable

just uncomfortablejust comfortable

comfortable

very comfortable

TNZwarmTNZcoldthermal comfort TNZwarmthermal comfort TNZcold

Temperature in ˚C

Rel

ativ

e en

ergy

exp

endi

ture

Example effect heat acclimation""Increase thermal comfort"

before heat acclimation"

after heat acclimation"

Comfort zone before and after (mild) cold/heat acclimation"

ambient temperature"

heat

pro

duct

ion"

28 32 °C"

Comfort zone unacclimated!

Heat acclimation!Cold acclimation!

34

Light, thermal physiology and comfort"

Poster: Marije te Kulve: poster 444 session 4 13:30h!

35 Poster: Marije te Kulve: poster 444 session 4 13:30h!

Light, thermal physiology and comfort" Body composition and heat balance"

Savastano et al., AJCN 2009!

37

Modeling the thermoneutral zone"

Boris Kingma: oral 512 tomorrow 9:30 h! 38

Comfort zone"

Boris Kingma: oral 512 tomorrow 9:30 h!

Modeling the thermoneutral zone and comfort"

future thermal comfort models"

  Include physiology (body composition)"

  Take individual differences into account"

  Include dynamic indoor environment"  Optimal comfort NOT maximal comfort"

  Include health"

  Include other environmental factors"  light/noise""

  Need to exercise our thermoregulatory system as part of a healthy lifestyle (use it or lose it )"

  By regular exposure outside the thermoneutral zone:"  Increase energy expenditure and brown adipose tissue"

  Increase insulin sensitivity"

  Increase resilience to more extreme weather conditions (important for healthy aging)"

"

40

Healthy thermal environment"

  Allowing indoor temperatures to drift may be healthy …"

  … and contribute to a sustainable built environment:less (fossil) energy consumption"

"  Lifestyle programs: diet, physical activity in a

healthy environment taking into account individual differences "

Temperature training"!

Department

""

Thanks to: Peter Op ‘t Veld Luc Schlangen Boudewijn Brans Patrick Schrauwen Boris Kingma Lisje Schellen Hannah Pallubinsky Marije te Kulve Maarten Vosselman Anouk van der Lans Evie Broeders Mark Hanssen Nicole Bouvy Roel Wierts Jaap Teule

Funded by NOW ZonMW – TOP !RVO: INTEWON – EOS LT10033!DIABAT - HEALTH-F2-2011 !RVO: TKI Energo ! !STW-Philips partnership!