Institute of Energy and Sustainable Development Towards thermal comfort prediction for the older population: a review of aging effect on the human body Divine T. Novieto, Dr. Yi Zhang 21 st May 2010 IESD PhD Conference: Energy and Sustainable Development

Institute of Energy and Sustainable Development Presentation Outline Information on Aging Aging effect on the body IESD-Fiala thermoregulation model Insight into the New Model Simulation and Results

Institute of Energy and Sustainable Development Aging Is the detrimental changes with time that underlie an increasing vulnerability to challenges thereby decreasing the ability of the organism to survive. Also referred to as the progressive accumulation of changes with time that are associated with the ever- increasing susceptibility to disease and death which accompanies advancing age. Most developed countries have accepted the chronological age of 65 years as a definition of 'elderly' or Old person.

Institute of Energy and Sustainable Development Some Theories of Aging Wear-and-tear -Normal wear and tear causes cells to function improperly Cellular- Cells replicate a specific number of times and then die. Nutritional Model Theory- Animals fed 50-60% less than it eats on its own lives longer Assumption: Lean mass, as opposed to adipose tissue results in greater health Ref [1] Ref [2]

Institute of Energy and Sustainable Development The Aging Situation As we age, we experience changes in our solid organs and body functions, these changes lead to diminished physiological reserve resulting in the inability of the body to maintain thermal comfort in times of challenge (hypothermia & hyperthermia) Aging of populations around the world with nearly 20% gain from age 65. By 2020 one fourth of the population in many nations around the world will be over Fig 1 the Europe situation. Ref [3] Ref [4]

Institute of Energy and Sustainable Development Age Concern In the 2003 heat wave, more than 2000 deaths were attributed to the August heat wave in England & Wales. Excess mortality was 33% in those aged 75+ and 13.5% in the under 75 age group during the 10 day heat wave. Deaths at home increased by 33% among those aged 75+, and deaths in Nursing homes increased by 42%. Around one quarter of the heat wave attributable deaths occurred in care homes. In France excess mortality was estimated at 20% for those aged years, at 70% for the year age group, and at 120% for people over 94 years.

Institute of Energy and Sustainable Development Effects of Aging on the Body

Institute of Energy and Sustainable Development Effects of Aging on the Body Skin:- Loss of subcutaneous fat, thinning of skin, decreased collagen, less sweat glands and difficulty in regulation of temperature. Musculoskeletal system:- Adipose tissue increases and lean body mass decreases, bone mineral content decreases, decrease in height from narrow vertebral spaces and increased arthritis. Ref [5]

Institute of Energy and Sustainable Development Effects of Aging on the Body Heart:- Limits of heart exertion reduced with age, Heart less able to pump efficiently, Blood vessels lose elasticity with age making heart have to pump harder to circulate blood Central Nervous system:- Neurons of central and peripheral nervous system degenerate, Nerve transmission slows (slower reflexes), hypothalamus less effective in regulating body temperature. Ref [6]

Institute of Energy and Sustainable Development The aging impact diagram The inter-relationship between the various components of the body including muscle, heart, central nervous system, skin and the effect aging as a natural phenomenon have on them.

Institute of Energy and Sustainable Development The IESD-Fiala Model IESD-Fiala model form the basis of this research and profiles the human body as two interacting systems, i.e. the controlled passive system (body structure) and the controlling active system (the thermoregulatory functions). The passive system diagram below is the focus of this paper. 19 spherical and cylindrical elements

Institute of Energy and Sustainable Development Revised model parameters Item Typical person (Fiala model) Typical old person (75yrs) Change BMR (W) % Cardiac Output (L/min) % Body Weight (kg) % Height (m) % Body Surface Area (m2) % Simulation scenario A transient simulation was carried out using the original IESD-Fiala model (FM) and the older person model (OP) to compare their dynamic responses to changing thermal environments of:- hot, cold and hot i.e. ( ) 0 C.

Institute of Energy and Sustainable Development Results Hand (palm) temperatureFeet temperature Lower arm temperature Lower leg temperature

Institute of Energy and Sustainable Development Conclusion The results from the simulations suggest that under the test conditions skin temperatures on the hand (palm), foot, lower arm, and lower leg were lower in the older person than in the average person. These findings are in line with earlier studies (Inbar, 2004):-that age related characteristics affect the overall rate of heat gain as well as the mechanisms through which this heat is dissipated. And (Anderson, 1996):- peripheral thermosensitivity appears to be progressively attenuated with age

Institute of Energy and Sustainable Development Finally The aim of this research is to develop a customized computer model for predicting thermal comfort of Old persons. The model is expected to predict old persons thermal responses (physical and physiological) and enable designers to estimate their comfort needs and reactions to diverse environmental conditions at the design stage. Hopefully we shall move …..from…this…. To ……..this..