Passive House Heat Loss Calculator
Calculate peak heating load, transmission, and ventilation losses using PHI methodology.
Building Geometry & Climate
Transmission Envelope (Areas & U-Values)
Ventilation & Infiltration
Heat Loss Breakdown (W/K)
* Calculations based on Passivhaus Planning Package (PHPP) simplified peak load formulas. Air heat capacity uses standard 0.34 Wh/(m³K). Infiltration calculated as n50/14. Output excludes internal/solar heat gains.
Tools to Also Try
The passive house heat loss calculator measures the exact peak heating load of your building based on its thermal envelope and ventilation metrics.
Architects, builders and energy consultants use this specific heating demand calculator to verify if their designs meet strict efficiency standards. You get immediate feedback on failing components before construction begins.
What the Passive House Heat Loss Calculator Does Designing a super insulated building requires precise math rather than rough estimates.
This tool processes your building geometry, climate data and material properties to reveal how much heat escapes through the fabric and air exchanges.
You input standard variables like treated floor area and ceiling height to establish the core internal volume.
Adding your target internal temperature and local winter design temperature creates the thermal delta needed for the calculations.
The passive house heat loss calculator then applies standard simplified formulas to generate your peak load.
Every building loses heat through two main pathways. Transmission losses occur as heat moves straight through solid materials like walls and roofs.
Ventilation losses happen when warm indoor air escapes and cold outdoor air replaces it.
The passive house heat loss calculator quantifies both pathways instantly. You get a clear visual breakdown showing the biggest thermal liabilities in your design.
Hitting the highest certification standard requires keeping your specific heating demand below 10 watts per square meter.
Our passive house heat loss calculator breaks down your total peak heat loss by element.
You see exactly how much heat bleeds through the roof versus the windows or the mechanical ventilation system.
Spotting a weak link early saves thousands of dollars in wasted materials you avoid installing undersized or oversized heating systems by knowing your exact numbers.
How to Use the Passive House Heat Loss Calculator Start by entering your basic building geometry and climate conditions.
Type the treated floor area and average ceiling height to establish the internal volume of your project.
Set your internal design temperature and the worst case winter external temperature for your specific climate zone. Small changes to the external temperature input will drastically alter your final output.
Move down to the transmission envelope section you need the surface area and planned U-value for your external walls, roof, ground floor and windows the passive house heat loss calculator asks for a thermal bridge allowance to account for structural junctions.
A standard timber or masonry construction with external thermal insulation will still have minor thermal bridges. Enter a realistic watts per Kelvin value here to keep your calculation accurate.
Finally, fill in your ventilation and infiltration parameters. Input your required air change rate for healthy hygienic operation. Add the efficiency rating of your heat recovery ventilator.
Type in your target or actual blower door test result for infiltration the passive house heat loss calculator immediately updates the specific heating load and generates a visual breakdown of your heat loss areas.
Who Needs This Specific Heating Demand Calculator Passivhaus designers rely on quick iterations during the early schematic phases of a project.
Plugging values into a massive spreadsheet takes time away from actual design work.
This passive house heat loss calculator provides a rapid diagnostic check to see if a proposed envelope assembly gets you close to the target. Designers catch fundamental flaws before drawing detailed construction plans.
Self builders constructing highly efficient homes use it to justify expensive material upgrades.
You can easily compare the thermal impact of triple pane windows against standard double pane units. Mechanical engineers check these figures to size backup heating elements correctly.
A passive house with an airtight envelope requires exceptionally small heating systems. Installing oversized equipment leads to short cycling and severe indoor comfort issues.
Real World Use Cases for Thermal Modeling An architect designing a retro-fit relies on this tool to balance difficult structural limitations.
Upgrading an old masonry building often leaves unavoidable thermal bridges around existing eaves or basement joints.
By inputting a higher thermal bridge allowance, the designer sees the exact energy penalty.
They can offset that loss by increasing the roof insulation thickness within the passive house heat loss calculator until the specific heating load drops back into the passing range.
A contractor ordering heat recovery ventilators uses the tool to test equipment specifications.
Dropping the HRV efficiency from 90 percent to 80 percent instantly shows the penalty on the total peak heat loss.
They present these numbers to the client to justify the cost of the premium unit over the budget option. The passive house heat loss calculator turns abstract percentages into tangible energy metrics.
Practical Tips for Accurate Heat Loss Results Garbage data creates completely useless outputs.
Always use the internal dimensions for your treated floor area not the gross external footprint.
Thick passive house walls consume a massive amount of floor space. Ignoring this fact inflates your specific heating demand artificially and ruins the math.
Keep your design external temperature realistic for your local climate data. Picking an extreme low that only happens once a century forces you to over insulate needlessly.
Rely on standard meteorological heating design temperatures instead the passive house heat loss calculator works best with steady state assumptions.
Never set the thermal bridge allowance to zero unless you have meticulously modeled every single junction in a dedicated thermal bridge program.
Even the best lost-form rigid insulation systems have minor installation flaws.
Adding a 5 W/K allowance gives you a safe buffer against real world construction imperfections the passive house heat loss calculator rewards conservative estimates.
Understanding Passivhaus Insulation Standards A core principle of passive house design involves continuous, gap-free insulation.
The roof insulation must connect directly to the wall insulation without interruption. High performance projects demonstrate how highly insulated eaves joints prevent cold spots entirely. The passive house heat loss calculator assumes you will build these joints correctly.
Placing the structural elements inside a thick layer of external thermal insulation keeps the entire structure warm. A few minor thermal bridges will not ruin the internal temperature stability.
Conversely if a major part of the construction remains cold, a single thermal bridge rapidly drops the internal surface temperature below the dew point.
This causes condensation, mold and structural rot over time. You must design out these flaws before testing your final numbers in the passive house heat loss calculator.
Frequently Asked Questions
What is the difference between peak heating load and annual heating demand?
Peak load tells you the maximum heating power needed on the coldest day of the year. Annual demand calculates the total energy consumed over a full heating season.
This passive house heat loss calculator focuses strictly on the peak load. You use this number to size equipment and check envelope compliance.
Why does infiltration use the n50 value?
The n50 metric comes directly from a standard blower door test conducted at 50 Pascals of pressure.
The passive house heat loss calculator divides this value by 14 to estimate natural infiltration under normal atmospheric conditions. A strict Passivhaus requires an n50 of 0.6 or lower to pass certification.
Does this tool replace official certification software?
No. The official planning package is a massive certification tool requiring days of data entry.
This passive house heat loss calculator uses simplified peak load formulas for rapid prototyping. You use it for initial feasibility testing before committing to the full certification process.
Accurate thermal planning prevents expensive mistakes on the job site. Testing your components early keeps your project moving in the right direction.
Use the passive house heat loss calculator to refine your envelope strategy and build a genuinely efficient home.
Start adjusting the inputs above to see how small changes impact your building performance.
