Advanced Energy and Ventilation Modelling of Existing Dwellings
This subtopic equips learners with the skills to use advanced software for simulating energy use and ventilation in existing dwellings, crucial for retrofit planning. It covers inputting building data, interpreting results, and predicting the impact of retrofit measures on both energy efficiency and indoor air quality. The modelling outputs directly inform decision-making to ensure compliance with the PAS 2035/2030 framework, enabling whole-house assessments that balance thermal performance with adequate ventilation.
Assessment criteria
Topic Overview
The GQA Level 4 Diploma in Retrofit Assessor is a specialised qualification for professionals conducting domestic retrofit assessments under the PAS 2035 framework. It covers the entire assessment process, from initial property survey to producing a detailed retrofit assessment report. This qualification is essential for ensuring that energy efficiency improvements are appropriate for each building's specific characteristics, avoiding unintended consequences such as damp or structural damage.
As a Retrofit Assessor, you will learn to evaluate a property's existing construction, heating systems, ventilation, and energy performance. You will identify improvement measures that align with the building's heritage, fabric, and occupancy patterns. This role is critical in the UK's drive to decarbonise homes, as poor retrofit work can lead to costly failures. The diploma ensures you have the technical knowledge and practical skills to deliver safe, effective, and durable retrofit solutions.
This qualification sits within the broader construction and building services sector, linking closely with retrofit coordinators, designers, and installers. It is regulated by GQA Qualifications and aligns with the PAS 2035:2019 standard, which is the gold standard for domestic retrofit in the UK. By mastering this diploma, you become a key player in the green construction revolution, helping to reduce carbon emissions while improving home comfort and energy efficiency.
Key Concepts
Core ideas you must understand for this topic
- →PAS 2035 Framework: Understand the process from assessment through design, installation, and evaluation, ensuring a whole-house approach to retrofit.
- →Building Physics: Knowledge of heat loss, moisture dynamics, and ventilation to avoid condensation, mould, and structural decay after retrofit.
- →Heritage and Traditional Buildings: Recognise that older buildings (pre-1919) require breathable materials and careful assessment to preserve their character and fabric.
- →Energy Performance Assessment: Use of tools like SAP (Standard Assessment Procedure) and RdSAP to calculate energy ratings and identify cost-effective improvements.
- →Risk Assessment and Mitigation: Identify potential risks (e.g., interstitial condensation, cold bridging) and specify appropriate measures to manage them.
Learning Objectives
What you need to know and understand
- 1. Introduction to energy and ventilation modelling software2. Simulating energy use and ventilation performance in existing dwellings3. Predicting the impact of retrofit measures on both energy and ventilation performance4. Use of simulation in planning, decision-making, and ensuring compliance with ventilation and energy standards as per the most current version of the PAS Retrofit Standards Framework
Assessment Criteria
Key criteria assessors look for in your portfolio
- Award credit for accurately setting up a baseline model of an existing dwelling, including correct input of construction types, U-values, air permeability, and occupancy profiles.
- Demonstrate competence by performing at least two retrofit scenarios, comparing predicted energy savings (kWh/year) and ventilation effectiveness (e.g., air exchange rates) against the baseline.
- Provide clear evidence of using modelling outputs to assess compliance with PAS 2035 ventilation requirements, such as identifying risk of under-ventilation post-retrofit.
- Show the ability to justify specification choices (e.g., insulation levels, MVHR selection) based on modelled impact, cost-effectiveness, and moisture control.
Assessment Guidance
Guidance for achieving higher grades
- 💡When presenting evidence, always include a justification for the software chosen (e.g., SAP, PHPP, dynamic simulation) and any limitations acknowledged.
- 💡Focus on the 'whole-house' approach: show how energy and ventilation are interdependent and how you balanced these in the retrofit plan.
- 💡Use the PAS 2035 Risk Assessment template to structure your modelling findings, clearly mapping each hazard to a mitigation measure.
- 💡Practice sensitivity analysis: demonstrate how varying input parameters (e.g., occupancy, climate data) affects outcomes, and explain how you accounted for uncertainties.
- 💡Always justify your recommendations with evidence from the survey. Examiners look for logical reasoning linking observed defects to proposed measures.
- 💡Pay close attention to the building's age and construction type. Using the wrong U-value or ignoring breathability can lose marks, especially for pre-1919 properties.
- 💡In the assessment report, clearly state any risks and how they will be mitigated. This demonstrates a thorough understanding of PAS 2035 requirements.
Common Mistakes
Common errors to avoid in your coursework
- Failing to calibrate the model with actual energy bills or air permeability test results, leading to inaccurate baseline predictions.
- Overlooking internal gains and thermal bridging in the energy model, resulting in underestimated heating demand.
- Assuming that adding insulation alone solves all problems without modelling the increased risk of condensation and poor ventilation.
- Misinterpreting ventilation modelling outputs, such as confusing air changes per hour with equivalent area, leading to non-compliant specifications.
- Misconception: All homes benefit from the same retrofit measures. Correction: Each property is unique; measures must be tailored to the building's construction, age, and occupancy to avoid damage.
- Misconception: Airtightness is always good. Correction: While reducing air leakage saves energy, uncontrolled airtightness without adequate ventilation can cause severe indoor air quality and moisture issues.
- Misconception: Solid wall insulation is the same for all solid walls. Correction: The type and thickness of insulation depend on wall material (e.g., stone, brick, cob) and exposure; inappropriate choices can lead to damp.
Frequently Asked Questions
Common questions students ask about this topic
Pass / Merit / Distinction Evidence Checklist
How your portfolio evidence is graded for GQA QUALIFICATIONS LIMITED Advanced Energy and Ventilation Modelling of Existing Dwellings
Every vocational unit is marked against named criteria rather than an exam percentage. Your tutor's brief lists the exact codes for this unit — here is what each band is asking you to do.
Demonstrate baseline knowledge, accurate terminology, and core practical application.
Provide detailed analysis, structured explanations, and clear workplace reasoning.
Deliver thorough evaluation, original problem solving, and fully justified recommendations.
Before You Start
Prior knowledge that will help with this topic
- •Basic understanding of building construction methods (e.g., cavity walls, solid walls, timber frame).
- •Familiarity with energy efficiency concepts such as U-values, thermal bridging, and condensation.
- •Knowledge of health and safety practices for domestic property surveys.
Coursework AI Review
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Key Terminology
Essential terms to know
- 1. Introduction to energy and ventilation modelling software2. Simulating energy use and ventilation performance in existing dwellings3. Predicting the impact of retrofit measures on both energy and ventilation performance4. Use of simulation in planning, decision-making, and ensuring compliance with ventilation and energy standards as per the most current version of the PAS Retrofit Standards Framework
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