Amogh N P
✦ In loving memory of Amogh N P — Architect · Designer · Visionary ✦
An architect's screen showing a building-energy simulation — a 3D building model with a colourful solar-radiation and daylight analysis overlay and energy-use charts beside it, the sustainable design tested digitally before construction.
Unit VSustainable & Resilient Building Design

Building Performance Simulation

Testing the building's energy and comfort before it is built.

≈ 30 min + studio work

How do you KNOW your sustainable design will work? You simulate it. Building-performance analysis (BPA) uses software to predict a building's energy use, comfort, daylight and carbon from a digital model — so design decisions are tested and tuned BEFORE a brick is laid. This unit introduces BPA, the dominant impact of envelope design, the methodology of a simulation, and the tools used in practice — Design Builder, Comfen, Revit's energy optimisation and Autodesk Insight 360. Simulation turns sustainable design from hope into evidence.

Learning objectives

By the end of this unit, you will be able to — mapped to the course outcomes for Sustainable & Resilient Building Design:

1
CO6 · Understand

Explain building-performance analysis and why design decisions are tested by simulation.

2
CO4 · Understand

Describe the dominant impact of envelope design on a building's performance.

3
CO6 · Apply

Outline the methodology of a building-performance simulation.

4
CO6 · Understand

Identify the simulation tools used in practice and what each is for.

BPA, the envelope, the method

Predict before you build

BPA tests design options on a digital model; the envelope dominates the loads, so early envelope decisions matter most — and good inputs make trustworthy results.[1, 6]

The simulation loop model geometry+ fabric, systems attach weather+ schedules RUN engine(EnergyPlus) interpret EUI,comfort, daylight iterate — change one thing, re-run, compare Garbage in, garbage out — the inputs decide the answer.
DiagramThe building-performance simulation loop — model, add weather, run, interpret and iterate

Predict before you build

BUILDING PERFORMANCE ANALYSIS (BPA) uses physics-based software to PREDICT how a building will perform — its energy use, thermal comfort, daylight, glare and carbon — from a digital model of its geometry, fabric, systems, location and weather. Instead of guessing, the designer TESTS options (different glazing, shading, orientation, insulation) and sees the numbers, choosing the best before construction. It is the evidence base of sustainable design.[1]

The envelope is the big lever heat in heat out glazing shading The envelope decides: • how much heat enters/escapes • how much daylight gets in • how hard the systems work Small early envelope changes beat any later mechanical fix — find them with simulation.
DiagramSimulation shows the envelope dominates a building's loads — early envelope decisions beat later mechanical fixes
Design Builder, Comfen, Insight

The tools

Design Builder (whole-building energy), Comfen (facades) and Revit/Insight 360 (BIM-integrated) turn the strategies of this whole course into measured predictions.[1, 4]

The tools of the trade Design Builder whole-building energyEnergyPlus enginecomfort, HVAC,daylight, carboncode / net-zerocompliance Comfen facades &fenestrationcompare glazing,shading, WWRearly decisions(LBNL) Revit + Insight 360 BIM-integratedanalysisenergy, EUI,daylight, solarfast early-stagefeedback Simulation turns sustainable design from hope into measured evidence.
DiagramThe simulation tools — Design Builder for whole-building energy, Comfen for facades, Revit Insight for BIM-integrated analysis

Whole-building energy

DESIGN BUILDER is a leading graphical front-end to the EnergyPlus simulation engine (the open-source engine behind much building energy modelling). It does whole-building hourly energy, comfort, HVAC, daylight and carbon analysis — the workhorse for detailed energy modelling and code/net-zero compliance. The architect builds the model; EnergyPlus does the physics.[1]

Simulation in one table

At a glance

AspectOneThe other
Design decisionsGuessedTested by simulation (BPA)
Biggest leverLate mechanical fixesEarly envelope decisions
Model qualityGarbage in, garbage outGood inputs → trustworthy results
Tool focusComfen: facades/windowsDesign Builder: whole-building energy
Sustainable claimA hopeful sloganEvidence from simulation & metering
Vocabulary

Key terms

Building performance analysis (BPA)

Using software to predict a building's energy, comfort, daylight and carbon from a model.

Energy model

A digital model of geometry, fabric, systems, location and weather that the engine simulates.

Weather file

Typical-year hourly climate data attached to a model so it simulates the real local climate.

EUI

Energy Use Intensity (kWh/m²/year) — the headline output of an energy simulation.

EnergyPlus

The open-source physics engine behind much building energy modelling (e.g. via Design Builder).

Comfen

An LBNL tool for comparing facade/fenestration options early.

Insight 360

Autodesk's BIM-integrated energy/daylight analysis for early-stage decisions.

Iteration

Running a baseline, changing one thing, re-running, and comparing to optimise the design.

Apply it

Studio task — the capstone

For your passive design from Unit III, outline a building-performance simulation: what geometry, fabric, systems, weather file and schedules you would set, which tool you would use (and why), and which three envelope variables you would test first. Then state what result (EUI, comfort hours, daylight) would tell you the design works — turning your sustainable claims into evidence.

Check your understanding

Self-assessment

1. The main purpose of building-performance analysis (BPA) is to —

2. Simulation repeatedly shows the biggest lever on a building's loads is the —

3. Comfen is a simulation tool focused specifically on —

In a nutshell

Recap

Building-performance analysis predicts energy, comfort, daylight and carbon from a digital model — testing design before building.
Simulation shows the envelope dominates loads; early envelope decisions are the highest-leverage and cheapest to change.
A simulation follows a method — geometry, fabric, systems, location, weather, run, interpret; garbage in, garbage out.
Tools: Design Builder/EnergyPlus (whole-building energy), Comfen (facades), Revit energy + Insight 360 (BIM-integrated).
Simulation turns sustainable design — passive, envelope, net-zero — from hope into measured evidence a client and code official accept.
The evidence

References & further reading

  1. [1]Iyengar, K. — Sustainable Architectural Design: An Overview (Routledge, 2015); EnergyPlus / Design Builder / LBNL Comfen documentation.
  2. [4]Attia, Shady — Net Zero Energy Buildings (NZEB): Concepts, Frameworks and Roadmap (Butterworth-Heinemann, 2018).
  3. [6]Lechner, Norbert — Heating, Cooling, Lighting (Wiley, 2015).

Further reading

  • K. Iyengar — Sustainable Architectural Design (2015).
  • Shady Attia — Net Zero Energy Buildings (NZEB) (2018).
  • Design Builder / EnergyPlus / Autodesk Insight documentation.

Sources gathered and fact-checked June 2026. Published values vary by source, sample and method — treat as indicative and confirm against the cited standard before structural use.