Energy Analysis
Phân tích năng lượng
Simulate building energy performance, thermal loads, and select appropriately sized HVAC systems; compare design options on electricity consumption.
Common tools
Autodesk Insight, IES-VE, DesignBuilder
Value delivered
QCVN 09:2017/BXD requires energy performance calculation for civil buildings from 2,500 m²
Adoption in Vietnam
Strong growth in Vietnam driven by QCVN energy code and LOTUS/LEED trend from 2020+.
Level of Information Need (LOIN)
G = Geometry · A = Alphanumeric · D = Documentation (ISO 7817-1:2024 method). A blank cell means this use sets no specific requirement for that discipline/stage.
| Discipline | Concept | Schematic | Developed | Technical | As-built / Operation |
|---|---|---|---|---|---|
| Architecture | — | G2·A2·D0 | G3·A2·D1 | — | — |
| Structure | — | — | — | — | — |
| Mechanical | — | G2·A2·D0 | G3·A2·D1 | — | — |
| Electrical | — | — | — | — | — |
| Plumbing | — | — | — | — | — |
Critical stages: Schematic · Developed
Rationale: ARCH (building envelope / thermal zones) + MECH (HVAC systems). A2 mandatory from ST2: U-values, thermal mass, SHGC, HVAC system type. Per established BIM energy-analysis frameworks most parameters are set at LOD200 schematic and refined per-space at design development — hence G2/A2 at ST2 tightening to G3/A2 at ST3. D1 links the applicable energy code or rating scheme (QCVN 09:2017, LOTUS Energy).
What it really is
Energy Analysis builds a dedicated analytical model from the architectural and MEP BIM model — with geometrically closed rooms/spaces and envelope materials carrying full thermal properties (U-value, solar heat gain coefficient SHGC, emissivity) — then exports it in the open gbXML format to run thermal load, energy consumption and HVAC performance simulations in a dedicated engine built on EnergyPlus. Unlike a 3D model built to look at or issue drawings from, the analytical model does not need architectural detail — it needs correct envelope geometry and the correct climate data for the project's location. The output is not just a kWh/m²/year figure; it is the basis for quantitatively comparing passive design options (orientation, window-to-wall ratio, shading) and active ones (glazing type, envelope insulation, HVAC efficiency) before the design is frozen, then checking the result against the mandatory thresholds of QCVN 09:2017/BXD.
When to use
Mandatory under QCVN 09:2017/BXD for civil works with total floor area of 2,500 m² or more — offices, hotels, hospitals, schools, commercial buildings and apartments. Start as early as concept design with a preliminary massing analysis, then repeat it at every design gate until the envelope is locked — run it only after technical design is finished and there is no room left to change the design without incurring cost.
Prerequisites
- •Architectural and MEP models at a LOIN sufficient for energy analysis, with rooms/spaces geometrically closed — carried over directly from Design Authoring
- •The correct climate zone identified and a weather-data file matching the project location, not the software's default file
- •EIR or BEP stating the energy-performance target and the QCVN 09:2017/BXD threshold to be met
- •An engineer able to configure the simulation and interpret its results — not merely run the software
- •A project schedule that allows simulation early enough to still change the design before the envelope is locked
Inputs
Architecture task team · .rvt / IFC
Design consultant / nearest meteorological station · .epw / .stat
Appointing party · .pdf / .docx
Architecture task team · material suppliers · .xlsx
MEP task team · .rvt / IFC
Outputs
Energy simulation report
.pdf → Appointing party · competent construction authority
Accepted when: States thermal loads and predicted consumption by category and checks each QCVN 09:2017/BXD threshold individually — not a blanket pass/fail statement
gbXML file of the analytical model
.gbxml → Energy simulation engineer
Accepted when: Geometry is closed, no surface misclassified (e.g. an exterior wall read as shading)
Comparison table of passive and active design options
.xlsx → Design consultant · appointing party
Accepted when: Compares at least two options on the same energy-consumption metric, with a recommendation
QCVN 09:2017/BXD compliance dossier
.pdf / .xlsx → Competent construction authority
Accepted when: Covers every mandatory category: envelope, ventilation and air conditioning, lighting
General workflow
Prepare the energy-analysis model
Verify that rooms/spaces in the architectural model are geometrically closed, with no gaps in walls, ceilings or floors anywhere — a precondition for the software to compute each space's thermal boundary correctly before exporting gbXML.
Architect · BIM Coordinator · Revit (Room/Space Bounding, Energy Settings) → Energy-analysis model with closed rooms/spaces
Assign materials and thermal properties
Assign each envelope material layer its real thermal parameters: U-value, solar heat gain coefficient (SHGC), emissivity — never leave the software's generic defaults in place for every project.
MEP engineer · Architect · Revit (Material Thermal Properties) → Model with complete thermal properties
Run early massing analysis to compare options
As early as concept design, run a massing analysis to quickly compare orientation, window-to-wall ratio and form options before detailed design — a step often skipped, leaving the later detailed simulation to merely confirm an already-frozen design instead of helping choose one.
Architect · Autodesk Forma (energy analysis / Energy Use Intensity) → Massing options comparison
Export gbXML
Export the analytical model to the open gbXML format and check the export report for misclassified surfaces — for example an exterior wall read as a shading surface — before handing it to the simulation engine.
BIM Coordinator · Revit (Export gbXML) → gbXML file
Configure climate data and run the simulation
Load the gbXML into the simulation engine, select the weather-data file matching the project's actual location and climate zone — not the nearest default file in the software library — then run a full-year thermal load and energy consumption simulation.
Energy simulation engineer · Autodesk Insight (built on Green Building Studio) · IES-VE or DesignBuilder running EnergyPlus → Thermal-load and energy-consumption simulation results
Check against QCVN 09:2017/BXD
Compare the simulation results and envelope parameters against the mandatory thresholds of QCVN 09:2017/BXD, producing a category-by-category checklist — envelope, ventilation and air conditioning, lighting — not a single blanket pass/fail statement.
Energy simulation engineer · Design lead · Compliance checklist (internal template, no simulation software needed) → QCVN 09:2017/BXD compliance dossier
Submit and publish the report
Publish the simulation report and the compliance dossier to the CDE so the appointing party and the competent authority can both access them, with specific adjustment recommendations for any category that fails.
BIM Coordinator · Autodesk Forma Data Management (CDE) → Published energy-performance report
Diagram
↺ Run early at the massing-analysis step, then repeat the full cycle at every design gate — a one-off simulation retains little value beyond a slide
Common pitfalls
gbXML exports but the simulation errors out or thermal loads come out badly skewed
Cause: Rooms/spaces in the architectural model are not geometrically closed — gaps in walls, missing ceilings or floors in places — so gbXML produces a wrong analytical volume or omits surfaces
Fix: Run a Room/Space Bounding check in Revit and close every gap before building the energy-analysis model
Simulation results diverge sharply from the actual consumption of similar buildings in the same region
Cause: Using the software's default weather file or a weather station that does not match the project's actual location
Fix: Select the weather file that matches the project's location and the applicable QCVN 09:2017/BXD climate zone, checked against the nearest meteorological station
A complete simulation report exists but the design never changes as a result
Cause: The simulation runs only after the architectural design and envelope are already locked — no room left to adjust without incurring redesign cost
Fix: Run an early massing analysis at concept design to compare options, then repeat the detailed simulation at every design gate instead of waiting to do it once after technical design is finished
Two engineers simulating the same model produce noticeably different energy-consumption figures
Cause: No standardised approach to material assignment, occupancy schedules and internal-load assumptions — each engineer sets different default parameters
Fix: Agree a single set of assumptions (occupancy, lighting schedule, equipment loads) and record it in the BEP or an internal simulation procedure before running any model
Measuring effectiveness
Compare the total predicted consumption in the simulation report with actual utility-bill or metered data after the building is operating
Benchmark: 0.8% (DesignBuilder) and 0.93% (IES-VE) in one BIM-to-BEM comparison study on a specific building — a result specific to that study, not a universal threshold for every building or for Vietnam's climate
Compare the room/space volume computed in Revit with the volume the simulation tool recomputes after importing gbXML
Benchmark: About 10% in the same study, due to differing conventions: BIM measures to the wall's internal face, the simulation tool to the wall centreline — a convention difference, not a modelling error
Rooms/spaces passing the Room/Space Bounding check without gap errors, divided by the total number of rooms/spaces in the model
Benchmark: no independent benchmark — set an internal target
Working days from receiving the LOIN-compliant model to issuing the first simulation report
Benchmark: no independent benchmark — set an internal target
Legal basis
There is NO specific requirement for building energy analysis in Decree 217/2026/NĐ-CP — energy analysis falls under Article 8 generally. Art. 8(1)(a) makes BIM mandatory for new-build works Grade II and above, from the feasibility study or economic–technical report stage; Art. 8(2) assigns scope and information requirements — including an energy-performance target if the appointing party sets one — to the contract. The obligation to CALCULATE/VERIFY energy performance sits in a DIFFERENT instrument, not Decree 217: QCVN 09:2017/BXD (issued under Circular 15/2017/TT-BXD of the Ministry of Construction), mandatory for civil works with total floor area of 2,500 m² or more — a threshold independent of Decree 217's works-grade threshold. The consequence: a Grade II work under 2,500 m² must use BIM but is not bound by QCVN 09; conversely a work of 2,500 m² or more below Grade II must meet QCVN 09 even though BIM is not mandatory for it.
Sources
Only official sources (legislation, standards) and peer-reviewed academic work are cited. No vendor marketing figures or press sources. Reference only — does not replace legal advice.