MC Building Physics

Design question examples - Occupant needs

These are example design questions pertaining to the requirements of building's occupants.

MC Building Physics can answer these types of questions using a number of methods depending on your requirements.

Will the occupants be comfortable in my building?

Why investigate the feature?

The success of a building is closely related to the satisfaction of its occupants.

Thermal comfort (feeling hot or cold) is one of the more complex factors in occupant satisfaction and a considerable amount of research has been done on the subject.

As a result it is possible, with care, to make a good prediction of comfort in a space.

Thermal comfort diagram

What are the issues?

  1. What is the definition of comfortable?
  2. What are the predicted conditions in the building?

What are the criteria for comfort?

Possible criteria are -:

  • Temperature.
  • Fanger comfort criteria.
  • Adaptive comfort criteria.

Break the issues down

Agree comfort criteria with client -:

  • Define what the metric is e.g. air, operative or radiant temperatures, percentage of people dissatisfied.
  • Define the limiting value.
  • Define how often the limit can be exceeded.
  • Define the climate that the building will have its performance predicted for.

Predict the performance of the building for the chosen climate. For both types of system a full dynamic simulation is necessary to fully understand how the building might perform.

Will my building benefit from automatic daylight controlled lighting?

Why investigate the feature?

Having a daylit building has benefits both in terms of energy and occupant satisfaction.

Occupants will almost always prefer a space with a daylit appearance over artificial lighting.

If the daylight level is sufficient for task lighting then artificial light with its associated electricity use and heat gains can be turned off.

Daylight factor plot

What are the issues?

  1. What defines a daylit space?
  2. What are the predicted daylight levels in the building?
  3. Balancing daylighting and solar gains.
  4. Visual discomfort - glare
  5. Lighting controls - manual, daylight controlled etc.

What are the criteria for adoption?

Possible criteria are -:

  • Financial - Simple payback, NPV
  • Increased occupant satisfaction and hence productivity.

Break the issues down

Agree daylight criteria with client. -:

  • Define what the metric is e.g. lux on work surface, average daylight factor, distribution of daylight.
  • Define the limiting value.

Identify the spaces where daylighting might be possible and predict the daylighting performance of those spaces. Options for this include -:

  • Hand calculation based on building geometry.
  • Computational methods.

Examine the potential savings due to automatic daylighting control. Options include -:

  • Rule of thumb estimates.
  • Based on average daylight factor.
  • Full hourly annual simulation linking daylight and thermal simulation.

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