HOPE: Health Optimisation Protocol for Energy-efficient Buildings
Pre-normative and socio-economic research to create healthy and energy efficient buildings

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Energy and well-being

Directly following the oil cost crisis in the seventies, measures were hastily taken in many buildings to reduce their energy use. These measures were planned with only two objectives: energy efficiency and return on investment. The effects of these measures on indoor environment, health or comfort were completely neglected. Therefore, in many cases, the results were dramatic. Not only comfort was decreased, but cases of mould growth, increased indoor pollution, and health hazards were observed. Since then, there seems to be a conflict with the aim of saving energy in buildings and the aim of creating a good indoor environment quality

Functions of the building requiring energy, together with some ways to save energy and effects of these energy saving measures on comfort:

Energy required for

Ways to save energy

Impact on indoor environment

Compensation of transmission heat loss in winter

Better, thicker insulation, low emissivity-coated multiple glazing.

Improves comfort

Improves health by preventing mould growth.

Compensation of ventilation heat loss in winter

Lower ventilation rate
Limit the ventilation rate to the required level

Use heat recovery on exhaust air.

May result in low IAQ

Less drafts, less noise, good IAQ

Generally improves IAQ in winter.

Winter heating in general

Improve solar gains with larger, well placed windows.

Improve the use of gains by better insulation and good thermal inertia.

If windows are poor: cold surfaces.
Over-heating if poor solar protections.

If well planned: good visual contact with outdoor environment, excellent summer and winter comfort.

Elimination of heat gains during warm season

Use passive cooling

Use efficient, well commissioned and maintained systems

Higher internal temperature

Very comfortable in appropriate climates and buildings.

Better IAQ and comfort

Should be kept within comfort zone.

Internal temperature control

Comfortable set-point temperature, improved control

Avoids over- and under-heating


Switch it off.

No effect in many cases.


Use daylighting

Use efficient artificial lighting.

Comfortable light, with limited heat gains when well controlled.

Comfort depends on the quality of light. Limited heat gains.

Health and comfort in low energy buildings

75% of the buildings audited within the HOPE project were chosen for being designed to have a good energy performance. An indicator of the energy performance is calculated as follows. The amounts of all energywares (litres of oil, m³ of gas, kWh of electricity) delivered to the building, converted to kWh using the lower heating value are summed up to get the total delivered energy use. A rough approximation of primary energy use, in which a weight 2.5 was allocated to electricity, a unity weight being kept for the other energywares was also calculated. This total delivered energy use, in kWh, is divided by the conditioned floor area to take account of the building size. Since energy for heating and cooling was not metered separately from the other energy uses in most buildings, no correction is made for climate.

Some statistically significant differences between "low" and "high" energy buildings in the HOPE sample. P is the probability to get the difference by pure chance:


Mean values for



"low" energy

"high" energy


Mean number of SBS symptoms per person in apartment buildings




Mean number of SBS symptoms per person in office buildings




Comfort overall in offices in Summer
(scale from 1=satisfactory to 7=unsatisfactory)




Comfort overall in offices in winter
(scale from 1=satisfactory to 7=unsatisfactory)




How comfortable is your home?
(scale from 1=satisfactory to 7=unsatisfactory)





The following conclusions related to energy and well-being can be drawn from experience and surveys:

  • Energy consumption varies strongly from building to building. In practice, it depends more on planning, construction, and management than on climate ( Figure 9. 1), building type or HVAC systems.
  • It is hence possible to produce low-energy buildings with good indoor environment quality and pleasant architecture.
  • Good design is essential to achieve these objectives. If planning, construction, and management are performed by energy conscious persons, the result will be a low energy consumption with a good indoor environment quality
  • However, a single bad step (e.g. poor management or poor planning) may destroy the qualities of a building or the effects of a conscious management.

Healthy and comfortable buildings do not necessarily require much energy, and can have a limited impact on the environment. Smart managers, architects and engineers construct and operate buildings in a way that both good indoor environment and low energy consumption can be achieved. By contrast, expensive measures to improve the indoor environment are sometimes counterproductive: even when technical requirements (temperature, airflow rates, etc.) are met, occupants may not feel well because they lack control on the system or don't trust it.

The existence of buildings that are healthy, comfortable and have a good energy performance, as well as the better comfort and health shown on the average by low energy buildings shows that the apparent conflict between comfort and energy use does not, in fact, exist.