Past paper type questions

Question 1

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

Answer 1

1. establish initial model and represent in a computer model;
2. calibrate model using reliable techniques;
3. assign boundary conditions of appropriate severity;
4. undertake integrated simulations using suitable applications;
5. express multi-domain performance in terms of suitable criteria;
6. identify problem areas as a function of criteria acceptability (e.g overheating);
7. analyse results to identify cause of problems (eg excessive solar gain);
8. identify design options by relating parameters to problem causes;
9. establish revised model for each option;
10. iterate from step 4 until overall performance is satisfactory;
11. repeat from step 3 to establish design replicability

Question 2

What is model calibration

Answer 2

An adjustment of model parameters to obtain an expected output.

Input-output pairs and measurements of output and time matched weather data is stored.

This data is used to create a meta-model to best emulate the simulation.

The meta-model is used to determine the input parameter values that will cause the tool to best reproduce the measured performance.

The best-fit input parameter values are then imposed on the initial model to yield the calibrated model.

Question 3

What is an integrated performance view

Answer 3

The Project Manager requires that a record be kept of the problem composition. At any stage it is possible to bring together the results for the different aspects of performance and to present these in the form of an integrated Performance View in order to summarise issues such as seasonal fuel use, environmental emissions, comfort, daylight utilisation, renewable energy contribution etc.

Question 4

Identify 3 principal criteria that should be included in an integrated performance view for the case of low energy house design

Answer 4

1. Energy demand, to understand what is required in typical circumstances.
2. Local renewable energy resource, to alter the demand profile to accommodate the integration of active renewable components.
3. Power quality, to ensure the quality of supply is not compromised.