Building Loads & HVAC Optimization
Accurate loads. Right-sized systems. One model from loads to energy.
We calculate room, system and plant loads in detail, check them against the design, and use the model to identify HVAC optimization opportunities. Where required, the same IESVE model becomes the foundation for whole-building energy modeling—keeping the analysis consistent from load calculation through system design and energy performance.
Why Loads Matter
Heating and cooling loads influence the size of almost every major component of a mechanical system—including airflows, terminal units, ducts, pumps, pipes, chillers, boilers, heat pumps and central plant.
When loads are overestimated, systems can be oversized, increasing capital cost and reducing part-load efficiency. When loads are underestimated, systems can struggle to maintain comfort, humidity and required operating conditions.
Getting loads right is one of the earliest and most cost-effective opportunities to optimize an HVAC design.
But load calculation should not be the end of the analysis.
Once the loads are established, they can be used to test the proposed HVAC system, check equipment sizing, evaluate operating strategies and identify opportunities to reduce or serve those loads more efficiently.
How We Calculate Loads
ASHRAE Heat Balance Method
We perform detailed heating and cooling load calculations in IESVE using the ASHRAE Heat Balance Method, a rigorous approach that accounts for solar gains, conduction, convection, radiation and thermal mass when determining building loads.
Our methodology supports the requirements of ANSI/ASHRAE/ACCA Standard 183 for peak heating and cooling load calculations.
The result is a physics-based load calculation rather than a simplified rule-of-thumb approach.
Mechanical engineering firms we work with in Canada have moved their load calculations to this approach and use our models directly in their design process.
Space-by-Space Detail
We can model individual spaces using actual project information for:
- Occupancy and operating schedules
- Lighting loads
- Plug and equipment loads
- Ventilation requirements
- Building envelope and constructions
- Specialty equipment
On large projects, we have modeled more than 1,500 individually defined spaces, including spaces with highly specific loads such as MRI and CT rooms, commercial kitchens and other specialized areas.
This level of detail allows the design team to understand where loads actually originate rather than relying on generalized assumptions across an entire building.
Room, System and Plant Loads
We calculate and report loads at the level required by the design team:
Space / Room → Zone → HVAC System → Plant
This allows us to establish:
- Peak room loads for terminal units
- System loads for air-handling equipment
- Heating and cooling requirements for central systems
- Plant loads for boilers, chillers and heat pumps
- Airflow requirements
- Load profiles for subsequent system and energy analysis
The result is a connected view of the building rather than an isolated peak-load calculation.
One Model, From Loads to Energy
One of the advantages of detailed IESVE modeling is that the load model can become the foundation for subsequent whole-building energy analysis.
Rather than rebuilding the building for every analysis, the same geometry, constructions, schedules, internal gains and HVAC assumptions can be developed further for annual energy simulation.
One model. Multiple design questions.
This creates continuity between load calculations, HVAC design and energy analysis and allows optimization decisions to be evaluated against the building’s annual performance.
From Loads to HVAC Optimization
Once room, system and plant loads are established, they become a tool for evaluating the HVAC design itself.
Check Plant Sizing
We compare calculated loads against the selected capacity of boilers, chillers, heat pumps and other plant to identify potential oversizing, undersizing and staging opportunities.
It is important to distinguish calculated load from installed capacity. Equipment capacity may intentionally exceed the calculated peak because of redundancy, staging, maintenance requirements or other design criteria.
Our analysis helps the design team understand the actual load before determining how much capacity should be installed.
Explicit HVAC System Modeling
Where required, we model the proposed HVAC system, equipment and operating logic rather than treating the HVAC system as a simple load multiplier.
This allows us to evaluate how the system responds across different operating conditions and identify opportunities involving:
- System configuration
- Equipment staging
- Heat recovery
- Airflow and temperature control
- Part-load operation
- Plant sequencing
- Operating schedules
- Setpoints and control strategies
This is particularly valuable when the goal is not simply to size the equipment, but to understand how the system will actually operate.
Optimizing Ventilation Loads with Heat Recovery
Ventilation can be a significant component of HVAC heating and cooling requirements, particularly in buildings with high outdoor-air requirements.
Once the building and HVAC loads are established, we can evaluate heat-recovery strategies using our ERV Analysis Tool.
The analysis can evaluate different recovery efficiencies, operating conditions and system configurations and quantify their impact on heating, cooling, humidification, energy consumption, operating cost and emissions.
An ERV does not change the fundamental space loads from occupants, lighting, equipment, envelope and solar gains. Instead, it can reduce the ventilation-related heating and cooling load seen by downstream HVAC equipment.
The actual benefit depends on airflow, sensible and latent effectiveness, climate, operating schedules and control strategy.
Our ERV analysis can quantify:
- Ventilation heating and cooling load reduction
- Sensible and latent energy recovery
- Preheat and post-heat requirements
- Humidification requirements
- Annual energy consumption
- Operating cost impact
- GHG emissions
- Different ERV efficiency and configuration scenarios
This allows us to move beyond simply sizing equipment and ask a broader question:
Can the ventilation load be reduced or recovered before we size and operate the HVAC system?
The results can then feed back into HVAC design and whole-building energy modeling.
Aligned with ASHRAE Standard 209
Building performance simulation is most valuable when it influences design decisions while those decisions are still open.
Our workflow supports the modeling approach described in ANSI/ASHRAE/IBPSA Standard 209, including analysis of load reduction strategies and evaluation of HVAC system options.
Rather than using energy modeling only to report annual consumption after the design is complete, we use modeling to help answer design questions along the way:
What is the load?
- How should the system serve it?
- Can the load be reduced or recovered?
- How should the equipment be sized and controlled?
- What is the annual energy and operating impact?
Healthcare & Specialty Buildings
Healthcare facilities are a good example of why detailed load modeling matters.
Airflow requirements may be driven by both thermal loads and healthcare ventilation requirements. On hospital projects, we compare calculated thermal airflow requirements with the applicable CSA ventilation requirements and identify which condition governs each space.
This helps the design team size systems based on the actual governing requirement rather than relying on generic assumptions.
Our project experience includes:
Hospitals · Schools · Multifamily Residential · Museums · Personal Care Homes · Commercial & Institutional Buildings
Geothermal Load Modeling
More than 30 mid- to large-scale geothermal projects modeled in Canada
Geothermal design requires a different type of load analysis.
The critical question is not simply the peak heating or cooling load of a space, but the hourly loads seen by the heat pump coils and ultimately the ground loop over the life of the system.
We develop detailed annual load profiles and separate loads by system and source, including:
- Preheat coils
- Reheat coils
- Make-up air units
- Domestic hot water
- Heating and cooling systems
- Other loads connected to the geothermal system
This helps geothermal designers determine which loads should be served by the ground loop and which should remain on conventional or hybrid systems.
Why Accuracy Matters
Small changes in schedules, controls, setpoints or system configuration can significantly change annual geothermal loads.
An inaccurate model can therefore lead to an oversized, undersized or thermally imbalanced borefield.
Our geothermal modeling can provide:
- Hourly heating and cooling load profiles
- Coil-level and system-level load breakdowns
- Ground-loop heating/cooling balance
- Conventional vs. geothermal load allocation
- Strategies to reduce or rebalance ground loads
- Load profiles suitable for subsequent borefield design
Reducing the building or system load before sizing the ground field can also reduce drilling requirements and improve the long-term balance of the geothermal system.
What You Receive
Depending on the project, deliverables can include:
- Space-by-space heating and cooling load reports
- Peak heating and cooling loads
- Airflow requirements
- System-level load summaries
- Plant load calculations
- Equipment sizing checks
- Annual load profiles
- Geothermal load profiles
- HVAC system analysis
- ERV/heat-recovery analysis
- Design optimization recommendations
- IESVE model/data ready for subsequent energy modeling
Our Process
1 — Define the Design Question
We establish what needs to be calculated, checked or optimized and what design decisions the analysis needs to support.
2 — Build the Load Model
We develop the building model using drawings, Revit information, design criteria, equipment schedules and operating assumptions.
3 — Calculate Space Loads
We calculate detailed space-by-space heating, cooling and airflow requirements using the appropriate design conditions and modeling methodology.
4 — Aggregate Systems & Plant
Space loads are combined into HVAC systems and central plant to establish system and plant requirements.
5 — Review & Optimize
We compare calculated loads against the design, identify sizing issues and evaluate HVAC optimization opportunities.
6 — Evaluate Recovery & System Strategies
Where applicable, we evaluate heat recovery, ERV configurations, system strategies, controls and other measures that can reduce energy use or improve system performance.
7 — Carry the Model Forward
Where required, the model becomes the foundation for whole-building energy analysis and further design optimization.
Why ECOMatrix
ECOMatrix combines building energy modeling expertise with detailed HVAC load analysis.
We work independently of equipment manufacturers and equipment sales, so our recommendations are based on the project’s actual loads, operating conditions and design objectives.
Our experience spans complex commercial, institutional, healthcare, residential and specialty buildings—including projects with more than 1,500 individually modeled spaces and 30+ mid- to large-scale geothermal load modeling projects in Canada.
Most importantly, we don’t stop at calculating the load.
We use the model to ask whether the load can be reduced, recovered, served more efficiently, and ultimately optimized over the life of the building.
Have a system worth sizing right?
Send us your project. We’ll help determine the appropriate level of load modeling and what the analysis can tell you.