Ventilation Energy Consumption Calculator
This free calculator is available to our customers and other professionals. Simply enter basic details about your property and easily compare different air ventilation systems. With this ventilation energy consumption calculator, you can estimate the energy usage of your current ventilation unit in Finland’s climate and evaluate potential savings if an older unit is replaced with a new energy-efficient ventilation system.
The calculator is based on the information you provide, such as the type of ventilation unit, air exchange rates, annual operating hours, and heat recovery efficiency. It compares the energy consumption of your current and proposed new unit, taking into account fluctuations in outdoor temperatures and energy prices.
It is important to note that this calculator is an indicative tool. It does not guarantee precise values, as actual energy consumption depends on various factors, including system settings, building insulation, and user behavior. The purpose of this tool is to provide an overview of ventilation energy consumption and potential savings, but final decisions should be made in consultation with an expert. What This Calculator Actually Does and How User Interface Gathers building details like size, age, insulation, tightness, and ventilation type. Offers three current system types (gravitational, extraction, or older heat recovery) and three potential upgrades (optimized gravitational, EC extraction, or modern HRU). Adjusts visible input fields based on radio-button selections. For instance, if you pick an extraction fan, you reveal power and control-related inputs. Core Calculations Air change rate: Dynamically sets a base ACH (air changes per hour) based on building age, building type, and number of floors. Infiltration: Uses infiltration multipliers that shift based on system type—extraction or HRU modifies infiltration differently than a gravity system. Heating energy demand: Combines infiltration flow with any mechanical flow to compute total airflow. Then calculates the thermal loss (kWh/year) using an energy balance formula:Flow × ΔT × specific heat × air density × annual heating hours. Electricity consumption: Sums up fan motor power and (if selected) electrical heater coil usage. Also includes partial load factors for ventilation “performance levels” (away/home/boost). Cost: Multiplies the total energy demand by a chosen heating multiplier (depending on the heating type) plus the electrical usage, then by the electricity price (€/kWh). Outputs: Displays the results in four categories: Heating energy demand (kWh/year) Ventilation system electricity consumption (kWh/year) Total energy costs in € Actual air changes per hour Dynamic Updates Changing location auto-updates winter temperatures and heating hours. Checking/unchecking “equipped with electric resistance” sets the extra heating coil usage for the HRU. “Optimized” extraction system references a typical AC fan and then calculates EC fan power based on an EC_EFFICIENCY_FACTOR. The script updates infiltration and fan parameters whenever the user modifies relevant inputs. Under-the-Hood Assumptions Fixed climate data: The script uses preset average winter temperatures and annual heating hours for different regions (Southern Finland, Central Finland, etc.). Real-life climates vary year to year, so it’s an approximation. ACH table: The air change rates come from the ACH_TABLE with broad categories (e.g., “before 1960” or “2000-2020”). It’s a simplified approach but reasonable as a first-pass design assumption. Infiltration factors: If you pick extraction or HRU, infiltration is multiplied by a factor (e.g., 1.1 for extraction, 0.8 for HRU). This lumps in the idea that certain systems alter how much air naturally leaks in. Heating multiplier: The code includes a method (calculateHeatingMultiplier) that checks if an HRU coil is large enough to handle the required heating. It calculates a fraction (the coil’s actual used capacity) to avoid unrealistically attributing 100% of the heater’s nominal power. Energy pricing: Only electricity price is input. Fuel-based multipliers are simplified to a single numeric factor (like 1.50 for oil or 0.30 for ground-source heat pumps), so the final cost is still expressed in terms of electricity rates. This is a broad assumption but keeps the calculator’s interface simple. How Accurate It Is Accuracy depends on how well your actual building and climate match the categories in the code. For a typical house with normal infiltration and heating patterns, the results can be a decent estimate. The infiltration approach includes a ratio that factors in temperature difference (1 + Math.abs(indoor - outdoor)/50), but real infiltration can also depend on wind and occupant behavior. By design, this is a high-level “best guess” tool, not a full HVAC design simulator. But within those constraints, it’s consistent and plausible. It shows relative differences (current vs. new) well enough to guide decision-making. Summary This calculator helps visualize how changes in ventilation affect a building’s energy consumption and costs. The results are indicative and allow for rough estimates regarding ventilation system optimization. Significant differences in kWh or € values typically indicate better heat recovery efficiency or reduced air leakage.