Frequently asked questions

You can carry out two types of assessment with HEAT, using 1) data from a single point in time; or 2) before and after data.
You will need the following data for an assessment:

• An estimate of how many people are walking or cycling.
• An estimate of the average duration spent walking or cycling in the study population. This can be entered as duration, distance, trips or (for walking) steps.

In addition, HEAT requires the following information, for which you can use the provided default values or local data, as available:

• mortality rate
• value of a statistical life
• time period over which you wish average benefits to be calculated
• optionally:
  • a discount rate
  • cost of promoting cycling or walking.

More information can be found here

It is suggested that HEAT be used for regular behaviour such as commuting, and the pensionable age is about 65 years in most countries. After retirement, physical activity behaviour (especially that related to commuting) can change. In addition, many mortality databases give mortality rates for up to 64-year-olds. The HEAT advisory group (see also here) thus agreed that the recommended applicable age range for HEAT for cycling is approximately 20–64 years.

For HEAT for walking, the relative risk estimate from a meta-analysis is used (see also here index.php?pg=walking&act=more1, and the advisory group recommended that this relative risk shall be applicable for an age range of approximately 20–74 years, as walking behaviour seems to be more sustained than cycling.

You may wish to use HEAT for slightly younger or older age groups than those recommended. However, if the age distribution in the assessed population is significantly different (much younger, much older) HEAT may over or under estimate the resulting benefits. In such cases, it is important to adjust the mortality rate which depends strongly on the age of the assessed population. However, HEAT should not be applied to populations of children (see also question “Can I use HEAT for children?”), very young adults, or older people, since the relative risk used by HEAT does not include these age groups.

Age is also of relevance regarding the mortality rates used. Mortality rates vary substantially by age, and thus the choice of age range for the rate used in an economic appraisal can have a significant impact on the calculated benefits. Therefore, the age groups to which the results may be applied and for which mortality rates were used should be made explicit. If any model is subsequently applied to other than the recommended age groups, any related assumptions should also be made explicit.
HEAT users can use a European average or a national rate from the WHO European Detailed Mortality Database for an average population (about 20-74 years old), a younger average population (about 20-45 years old) or a predominantly older average population (about 46-74 years old), or the local mortality rate can be entered.

However, the vast majority of epidemiological studies have been conducted on adults, mainly because the most commonly studied disease end-points such as coronary heart disease or death are rare in children, and studies on adults are easier to carry out. Thus the evidence base for the chronic health effects of physical activity on young people is not as large as that for adults. The HEAT advisory groups (see also here) concluded that the evidence for children and adolescents was insufficient, and that economic appraisals should focus on adults only in the first instance.

HEAT is designed for habitual behaviour, such as walking for commuting, or regular leisure time activities. Do not use it for the evaluation of one-day events or competitions (such as walking days, cycling events etc.), since they are unlikely to reflect long-term average activity behaviour. So if you are confident that your project will have a lasting effect on the walking or cycling behaviour or your local population, you may use HEAT. It is suggested to run different calculations based on different assumptions, for example on the long-term effect of your project.

Please also make sure that you use a mortality rate that reflects the age range of your local population as best as possible (see also FAQ on age range above).

You can carry out two types of assessment with HEAT, using 1) data from a single point in time; or 2) before and after data. So if you do not have baseline data, you can use HEAT to calculate the health benefits from the estimated or measured behaviour at the end of your project but you cannot compare it to the situation before the project started.

Please also bear in mind that HEAT is designed for habitual behaviour, such as walking for commuting, or regular leisure time activities. So only use HEAT if you are confident that your project will have a lasting effect on the walking or cycling behaviour of your local population. It is suggested to run different calculations based on different assumptions, for example on the long-term effect of your project.

HEAT is to be applied for assessments on a population level, i.e. in groups of people, not in individuals. In addition, HEAT is designed for habitual behaviour, such as walking for commuting, or regular leisure time activities, not for single-day events. So only use HEAT if you are confident that your project will have a lasting effect on the walking or cycling behaviour.

HEAT is meant to be applied for walking of at least moderate pace (i.e. about 3 miles/hour or 4.8 km/hour). This is in line with the walking speed of the studies in the meta-analysis (where available) to derive the relative risk for HEAT for walking (see also here index.php?pg=walking&act=more1)  and equivalent to the minimum walking pace necessary to require an energy expenditure that is considered to be necessary for health benefits (see also here index.php?pg=walking&act=introduction).

For HEAT cycling, an average speed of 14km/h is used, based on information from the study used to derive the relative risk, combined with data from the Stockholm commuting studies (see also here index.php?pg=cycling&act=introduction.more).

If the walking or cycling pace in the study population is unknown, these default speeds should be borne in mind as an underlying assumption.

The consensus meetings for the development of HEAT recommended, for the time being, focusing only on all-cause mortality for HEAT for walking and for cycling. It should be noted that this method is likely to produce conservative estimates, since it does not account for disease-related benefits.

However, it is fully recognized that physical activity has beneficial effects on many aspects of morbidity as well. From a public health point of view, these benefits materialize more rapidly than reductions in mortality. They can also be important in motivating individuals to walk and/ or cycle, as people may be more likely to increase their physical activity to improve their immediate health and well-being than to prolong their life. Nevertheless, the current evidence on morbidity, both for walking and for cycling, is more limited than that on mortality. Thus including the impact of morbidity in an economic appraisal leads to greater uncertainty.

However, addressing morbidity was identified as an important item for later refinement to broaden HEAT’s appeal.

No, It is not possible to change the relative risks used. The relative risks for HEAT cycling (see also here) and HEAT walking (see also here) have been selected based on an extensive consensus finding process (for more information see also “Methodology and user guide” here) taking into account the best available evidence at the time and are considered to be widely applicable.

HEAT is a European-developed tool. Therefore, the default values and drop-down options contain European values. However, other values can be entered by the user, in particular for the mortality rate and the value of statistical life. Indeed, for both these values it is important to use values which correctly represent the local situation.

The willingness to pay shows how much a representative sample of the population (who, in this instance, are potential victims) would be willing to pay (in monetary terms) for example for a policy that would reduce their annual risk of dying from 3 in 10 000 to 2 in 10 000. Based on this methodology, a standard “value of a statistical life” (VSL) can be agreed. This is often used in transport appraisals.

Whenever possible, enter a country-specific value or use a country value from the drop-down menu (not available for Andorra, Monaco and San Marino). If not known, European default values of €2.487 million (WHO European Region), €3.387 million (EU-27 countries) or €3.371 million (EU-28 countries including Croatia) can be used

 (see also here). Please bear in mind that such assessments do not assign a value to the life of one particular person but refer to an average value of a “statistical life”.

The value of a statistical life is derived with a method called “willingness to pay” (see also question “what is the “willingness to pay”?). According to economic theory, the willingness to pay comprises lost consumption, immaterial costs (e.g. suffering) and the share of health costs paid directly by the victims. Thus, it includes the whole part of the costs to society borne by individuals but not the part borne by society (i.e. the rest of the health costs, administrative costs, lost production, costs for re-assignments, etc.). For more information see for example here.

HEAT was developed to be used primarily by transport planners traffic engineers; and other interest groups working on transport, walking, cycling or the environment. They are familiar with calculations based on the value of a statistical life (VSL). Metrics used predominantly in the health sector, such as DALYs, are not directly applicable to this target audience. While these approaches have many inherent advantages, using such metrics would have considerably limited the usefulness and appeal of HEAT for the primary target audiences.

While the tool is also of general interest to health economists, physical activity experts or health promotion experts, due to the use of transport- specific methods such as VSL, the results of HEAT in its current form might need to be accompanied with additional information and explanations for such audiences.

Based on feedback from the users, in most cases they have either walking or cycling data. So integrating walking and cycling into one tool would have meant to provide a lot of unnecessary information to many users.

If an intervention increases cycling but reduces walking, these changes can be calculated using HEAT cycling and HEAT walking sequentially.

Economic transport appraisals usually cover other issues as well, in particular effects on injuries, air pollution, noise or traffic flow / congestion. HEAT can be used to complement such existing tools to integrate health effects which thus far are often not considered.

Usually, such broader economic transport appraisal tools are developed on national level. So please contact your national Ministry of Transport for more information.

HEAT is currently available in English. Translations into Finnish, German, Spanish and Russian are underway. If you are interested in translating HEAT and/or the “Methodology and user guide” (see here), please contact heat@euro.who.int.

More information on the development process and the methodology used can be found in the or the “Methodology and user guide” (see here)