The evidence guide provides advice on assessment and must be read in conjunction with the performance criteria, required skills and knowledge, range statement and the Assessment Guidelines for the Training Package.

Overview of assessment

A person who demonstrates competency in this unit must be able to evaluate the thermal loads for a commercial refrigeration system and for a multiple zone commercial or industrial building.

Critical aspects for assessment and evidence required to demonstrate competency in this unit

Assessors must be satisfied that the candidate can competently and consistently:

determine HVAC/R system parameters

investigate sustainability implications of HVAC/R systems

identify relevant thermodynamic principles and techniques for particular HVAC/R system thermal load evaluations

review features and functions of HVAC/R systems and components

test and measure HVAC/R systems and component performance parameters

evaluate system and component performance with tabulated and software generated data

apply and validate software for analysis and simulation

report and document results.

Context of and specific resources for assessment

This unit may be assessed on the job, off the job or a combination of both on and off the job. Where assessment occurs off the job, then a simulated working environment must be used where the range of conditions reflects realistic workplace situations.

The competencies covered by this unit would be demonstrated by an individual working alone or as part of a team.

Where applicable, reasonable adjustment must be made to work environments and training situations to accommodate ethnicity, age, gender, demographics and disability.

Access must be provided to appropriate learning and/or assessment support when required. Where applicable, physical resources should include equipment modified for people with disabilities.

Method of assessment

Assessment must satisfy the endorsed Assessment Guidelines of the MEM05 Metal and Engineering Training Package.

Assessment methods must confirm consistency and accuracy of performance (over time and in a range of workplace relevant contexts) together with application of underpinning knowledge.

Assessment methods must be by direct observation of tasks and include questioning on underpinning knowledge to ensure correct interpretation and application.

Assessment may be applied under project-related conditions (real or simulated) and require evidence of process.

Assessment must confirm a reasonable inference that competency is not only able to be satisfied under the particular circumstance, but is able to be transferred to other circumstances.

Assessment may be in conjunction with assessment of other units of competency where required.

Guidance information for assessment

Assessment processes and techniques must be culturally appropriate and appropriate to the language and literacy capacity of the candidate and the work being performed.

Required skills

Required skills include:

determining HVAC/R system parameters from plans, specifications and site inspections

reviewing features and functions of HVAC/R system components

investigating sustainability implications of HVAC/R systems

identifying relevant thermodynamic principles and techniques

testing and measuring system and component performance parameters

evaluating system thermal loads and relationship to, and implications for, component sizes and system performance

selecting and using appropriate calculations, techniques and software for analysis and simulations

validating software and software techniques required for thermal load evaluations

reporting and documenting processes, results and recommendations

Required knowledge

Required knowledge includes:

WHS and regulatory requirements, codes of practice, standards, risk management and registration requirements

sources of professional and technical assistance

current options and trends in performance analysis software, including underpinning program techniques

thermal load measuring equipment and test apparatus

sustainability implications of HVAC systems, including consideration of energy sources and energy efficiency

thermodynamic principles required by thermal loading analysis and HVAC/R management systems

thermodynamic concepts related to HVAC/R:

properties, process and state

mass, conservation of mass, specific volume and density, specific volume, relative density, force, weight, pressure, temperature, Zeroth law, absolute scales and International System of Units (SI) units

systems, cycles and steady state

energy forms

effects of heating of solids and liquids

heat transfer, conduction, convection and radiation:

property tables for conductivity, convection and radiation coefficients

Fourier law of conduction and conductivity of materials

convection:

mechanism of convection

convection heat transfer coefficient and factors affecting the coefficient

fluid flow characteristics (geometry of convection surfaces, natural and forced convection and flow regime)

units, kinematic viscosity and dynamic viscosity

convective heat transfer coefficients for conduit and annular flow, hydraulic diameter

heat exchangers (types, efficiency and measurements)

radiators:

emission, absorption and reflection (properties and measurements)

Wien’s displacement law

Kirchhoff’s law

solar energy, heating and power generation

radiant energy on surfaces

variations, such as Azimuth and zenith angles, path length, cloud cover and water vapour, and shade factors for windows

combined heat transfer

conduction plus convection, heat exchangers using air and water as transfer mediums

conduction, convection and radiation (qualitative)

cooling fins

heat flow, electrical analogy, graphical solution techniques and qualitative understanding of numerical methods

vapour compression refrigeration:

vapour-compression cycle for refrigeration

system components, including throttling valves and capillary tubes as throttling devices

performance criteria for refrigeration system evaluation

types of refrigerant

refrigerant properties and p-h diagrams:

ideal vapour compression cycle on the p-h diagram

energy balance and heat transfers in compressor, evaporator and condenser

variation of actual cycles from the ideal

vapour-compression cycle with suction superheating, liquid sub-cooling and pressure drop in system components

mechanical components of vapour compression (refrigeration and HVAC systems)

refrigeration enclosures, cabinets, cold rooms and freezer rooms

factors affecting refrigeration heat transfer

building thermal performance survey procedures

standard thermal values in relation to a commercial/industrial building

equipment size for constant and variable volume systems and central refrigeration and boiler capacities

thermal properties of buildings and building materials

people loads

cost implications of air conditioning and heating designs

heat loads

thermal lag

occupant comfort and safety factors

The range statement relates to the unit of competency as a whole. It allows for different work environments and situations that may affect performance. Bold italicised wording, if used in the performance criteria, is detailed below. Essential operating conditions that may be present with training and assessment (depending on the work situation, needs of the candidate, accessibility of the item, and local industry and regional contexts) may also be included.

Sustainability

Sustainability is used to mean the entire sustainable performance of the organisation/plant, including:

meeting all regulatory requirements

conforming to all industry covenants, protocols and best practice guides

minimising ecological and environmental footprint of process, plant and product

maximising economic benefit of process plant and product to the organisation and the community

minimising the negative WHS impact on employees, community and customer

Appropriate technical and professional assistance

Appropriate technical and professional assistance may include:

technical support and advice relating to elements which have intrinsic dangers, such as:

high pressure

energised fluid vessels

high temperatures and heat energy capacity

wiring with high current control voltages above extra low voltage

professional support for technologies, such as:

specialist electric motor drives and controllers

specialist materials, plastics, metal alloys and nano materials

special processes, alloy welding, heat treatment, sealing and fastening

WHS, regulatory requirements and enterprise procedures

WHS, regulatory requirements and enterprise procedures may include:

WHS Acts and regulations

relevant standards

codes of practice from Australian and overseas engineering and technical associations and societies

risk assessments

registration requirements

safe work practices

state and territory regulatory requirements

Standards and codes

Standards and codes refer to all relevant Australian and international standards and codes applicable to a particular task

Building heat gains

Buidling heat gains are affected by:

external, internal and system heat gains

U values and infiltration rates for various wall and roof constructions

sun, Azimuth and altitude angles, and overall shade factors for various windows

Commercial refrigeration cabinets

Characteristics of commercial refrigeration cabinets include:

defrost systems/heat

temperature control

air flows (refrigeration)

air screens (refrigerated and ambient store)

types of evaporation

lighting

Miscellaneous heat

Miscellaneous heat loads on refrigeration systems include:

electrical load

human load

defrost load

machinery load

Relevant documentation

Relevant documentation may include:

thermal load audits

calculations for heating and cooling loads

building and refrigeration layouts

heating and cooling system and component arrangements

system improvement diagrams