Use in Practice

Question 1

Describe three principal issues faced by engineers when deploying detailed energy simulation tools in practice.

Answer 1

1. How to manage the application of simulation (who does what, when and where).
2. Implementation of a performance assessment method whereby each step in the process is clearly demarcated and controlled (model definition, calibration, simulation commissioning, results analysis, mapping to design decisions etc.).
3. How to quality assure models and the results they produce.

Question 2

In relation to energy systems simulation, select five principal program input parameters, state the nature of a related uncertainty and suggest what action might be taken to reduce this uncertainty.

Answer 2

1. Climate: Stochastic, leads to uncertainty of conditions for models etc.
2. Lighting: clouds & pollution, will impact on sky luminance distribution etc.
3. Glazing: Thermo-optical properties of glazing may exhibit a significant variation both within a given sample and between samples….
4. Ventilation: leakage uncertainty etc, A sensitivity analysis, giving the variation of the results when input data are changed, is usually required.
5. Occupant interactions: The physiological and psychological processes that give rise to particular occupant responses to their environment are not well understood and few models exists for use in predicting how people interact with ventilation, lighting and heating/cooling systems. The levels of heat and moisture production can vary significantly, both between individuals and as a function of the context.

Question 3

Describe the steps involved in undertaking a performance assessment using an integrated energy simulation program. For each step give an example of the required action and the related knowledge. (PAM steps)

Answer 3

1. Establish a computer representation corresponding to a base case design.
2. Calibrate model: compare predictions to some reference case using reliable techniques such as inter-model comparison.
3. Locate BC’s: e.g. temp, wind/ solar irradiance.
4. Perform simulations: eg covering energy, mass and momentum balance.
5. identify problem areas: such as overheating, analyse simulation results (eg flow-path magnitudes) to identify a cause of problems.
6. Find a solution to the problem: (eg change control system) by associating problem causes with appropriate design options.
7. Match the remedy to a reference model with an adequate level of resolution
8. iterate from step 4 until the overall performance is satisfactory.

Question 4

Identify five performance entities that might be displayed in an ‘Integrated Performance View’ and describe how together they might be used to refine the overall performance of a design.

Answer 4

1. seasonal fuel and power consumption;
2. environmental emissions;
3. thermal comfort;
4. visual comfort; and
5. installed plant capacity.