Your installer has sent a form asking for "floor plans", "sections" and a "window and door schedule". This glossary explains what each of those words means, why anyone wants that information and where to look for it. The entries stand alone - read only the one you got stuck on.
If you do not have something, that is not a problem: almost every item can be replaced by a measurement or a photo. You can also fill in part of the form and come back to it later.
One thing to know up front. Your installer's tool, HeatAlgo, calculates heat loss room by room to the European standard EN 12831-1 and radiant floor output to EN 1264. If your installer's account is set to imperial units, the app shows feet, ft², °F and Btu/h; the calculation itself always runs in metric, to those standards.
The documents your installer asks for
What each document gives
- Floor plan
- Room layout and dimensions, floor areas, and where the windows and doors are.
- Building section
- Ceiling heights and how the floors stack - this is where heated volume comes from.
- Window and door schedule
- The size of every window and door, often with the U-factor.
- Architectural drawings
- Wall, floor and roof assemblies: what is in them, and how thick.
- Energy rating or audit
- U-factors or R-values for the assemblies and the air leakage assumptions.
- DWG or DXF files
- The same plan in vector form - dimensions read off without redrawing.
The drawings beside each entry are examples, drawn the European way, as in the houses HeatAlgo was built around. Your own documents will look different - different tags, a different sheet layout, dimensions in feet and inches - because every architect draws their own way. They are here so you can tell which document is meant, not to compare line by line.
Floor plan
A drawing of one story seen from above - as if the house were cut through about 3 feet above the floor and you looked down. It shows the room layout, room dimensions and where the windows and doors are. There is usually one per story: basement, first floor, second floor, attic. You will find them in the architectural drawings.
What a floor plan looks like
Example
Building section
A drawing of the building cut vertically, from foundation to roof. A floor plan shows what is next to what; a section shows what is above what. Ceiling height comes from here, and from that the volume of air that has to be heated. It sits in the same set of drawings as the plans.
What a section looks like
Example
Window and door schedule
A table of every window and door: tag, size, quantity, often the U-factor. It sounds like paperwork and is one of the more important items - a large share of heat escapes through windows, so without their sizes the calculation would rest on assumptions. For a finished house, the window labels or a tape measure will do.
What a window schedule looks like
Example
| Tag | Size (W x H) | Qty | U-factor |
|---|---|---|---|
| W1 | 59 x 55 in | 3 | 0.16 |
| W2 | 94 x 87 in | 1 | 0.14 |
| W3 | 24 x 24 in | 2 | 0.19 |
| D1 | 39 x 83 in | 1 | 0.23 |
Architectural drawings
The set of drawings and descriptions the house was built from. The most valuable part for an installer is the description of the assemblies: what a wall is made of, in what order and how thick. That is what decides how well the wall holds heat.
How a wall assembly is stated - an example, a masonry wall with exterior foam insulation, layers from inside to outside:
| Layer | Thickness | R-value (h·ft²·°F/Btu) |
|---|---|---|
| Interior plaster | 0.6 in | - |
| Clay block | 9.4 in | about 5.5 |
| EPS foam insulation | 7.9 in | about 28.4 |
| Exterior stucco | 0.2 in | - |
| Whole wall, 18.1 in | about R-35, U-factor 0.028 Btu/h·ft²·°F |
In this wall the insulation takes up nearly half the thickness and gives almost all of the R-value. The energy rating sample below lists the same wall at 0.028.
Structural drawings
Drawings of the structure: foundation, floor framing or slabs, roof trusses. Needed less often, but useful for radiant floor heating, because they say what the floor rests on and how much can be built up on top of it.
Energy rating or energy audit
A document stating how much energy the house uses and how its parts perform. In Europe it is the energy performance certificate, produced on sale, letting or handover; in the US the closest documents are a HERS rating or an energy audit report. For an installer it is mainly a shortcut: it often lists the U-factors or R-values of the assemblies and the air leakage assumptions. It does not replace the calculation used to size equipment, but it can speed it up a lot.
What an installer looks for in a rating
Example
Energy performance certificate
Building energy class
Assembly data (U-factor, Btu/h·ft²·°F)
- Exterior wall
- 0.028
- Roof
- 0.023
- Slab on grade
- 0.049
- Windows
- 0.16
Not the colored band, but the table under it - U-factors that would otherwise have to be dug out of the drawings.
DWG and DXF files
Technical drawing formats from CAD software. Unlike a PDF or a photo, they carry real dimensions that can be read off without redrawing. If your architect handed over the drawings in these files too, they are worth attaching.
Terms about the house
Building assembly
Anything separating the heated interior from something colder: exterior wall, roof, floor over a basement or crawlspace, slab on grade, window, door. Your installer calculates the heat loss through each one separately. In HeatAlgo these are called building elements.
Assembly layers
A wall is rarely one material. A typical one has drywall or plaster, a structural layer (framing, block, brick, concrete), insulation and an exterior finish. Order and thickness matter - they decide how much heat escapes. If you do not have the drawings, anything helps: a photo from the build, an insulation invoice, what the builder remembers.
Insulation and R-value
The layer meant to keep heat inside: foam board (EPS, XPS, polyiso), mineral wool, fiberglass, spray foam. Two things matter for the calculation: what was used and how thick it is - together they give the R-value. Higher R is better. The difference between 2 and 8 inches of foam board is several times the heat loss through the wall - and often a whole equipment size.
Window U-factor
The number on a window's label saying how much heat it lets through. Lower is better. In the US it is printed on the NFRC label in Btu/h·ft²·°F; a European window's data plate gives the same thing as Uw in W/(m²·K).
Typical U-factors, from worst to best:
| Window | U-factor (Btu/h·ft²·°F) | Uw (metric) |
|---|---|---|
| Old wood window, single glazing | 0.88 Btu/h·ft²·°F | 5.0 |
| Double glazing from the 1990s | 0.46 Btu/h·ft²·°F | 2.6 |
| Modern double glazing | 0.19 Btu/h·ft²·°F | 1.1 |
| Triple glazing | 0.14 Btu/h·ft²·°F | 0.8 |
| Polish building code limit for a vertical window, since 2021 | 0.16 Btu/h·ft²·°F | 0.9 |
These are indicative values. Your own windows have their U-factor on the label or in the window schedule - that is the number that goes into the calculation.
Heated floor area and volume
Heated floor area is the square feet of floor in the rooms that are actually heated - excluding the garage and an unheated basement. Volume is the space those rooms enclose, area times ceiling height. Floor area drives radiant floor heating; volume drives ventilation.
Stage of the project
Your installer asks because it decides where the data comes from. At design stage everything is in the drawings. During construction some things can still be measured and changed. In a finished house the data is reconstructed from measurements and documents - and that is where an energy rating or audit helps most.
Terms about the system
Radiant floor heating and radiators
Radiant floor heating gives off heat across the whole floor area, so it works with low water temperatures (86 °F-104 °F) - which pairs well with a heat pump. Radiators give off heat from a small surface, so they need hotter water (113 °F-158 °F) and respond faster to a change of setting. Mixed systems are normal: radiant floors downstairs, radiators upstairs.
Manifold
The box where all the radiant floor loops meet - water leaves for the rooms here and returns here. Flow is set for each loop separately at the manifold, so each room gets as much heat as it was calculated to need.
Air-to-water and ground-source heat pumps
Air-to-water takes heat from the outdoor air - cheaper to install, no digging, but its efficiency drops in a cold snap. Ground-source (often called geothermal) takes heat from the ground through wells or a horizontal loop field - more expensive up front and it needs either yard space or drilling, but it runs steadily whatever the weather.
Ventilation: natural, exhaust-only, heat recovery
Natural ventilation relies on leaks and stack effect - no equipment, but no control over how much air escapes either. Exhaust-only ventilation pulls air out with a fan (a bath fan running continuously, for example). Heat recovery ventilation, with a heat recovery ventilator (HRV), is balanced mechanical ventilation that reclaims heat: outgoing air warms the incoming air. The choice weighs heavily in the calculation, because ventilation is one of the two main routes heat takes out of a house.
Comfort temperature
The temperature you want in a room - and a real input to the calculation, not a survey about preferences. The system is designed around specific values, usually about 68 °F-70 °F in living rooms and 75 °F in a bathroom. If you like it warmer, say so at the start, not after installation.
Terms most often confused
Four pairs that are easy to mix up
Heated floor area
Square feet of floor in the rooms that are heated.
Volume
The space those rooms enclose - area times ceiling height.
Two homes with the same floor area, one with sloped ceilings and one with 10 ft ceilings, have different volumes and different heat loss.
Equipment output (Btu/h)
How much heat the heat pump delivers in the coldest hour of the year.
Annual use (kWh)
How much energy the system uses across a season.
The first number decides which unit to buy. The second decides what running it costs you.
Energy rating
A document stating annual energy use and how the house performs.
Heat loss calculation
The heat the house needs, worked out room by room.
A rating can be a good source of data, but it is not enough to size a heat pump or radiators.
Floor plan
A story seen from above. Shows what is next to what.
Section
The building cut vertically. Shows what is above what.
Areas come from the plan, heights from the section. The calculation needs both.
Where this form came from
The form you received is the HeatAlgo client form - a tool installers use to collect the data for their calculations without a dozen rounds of email. You can fill it in the classic way, or let AI read the values out of documents you upload; you approve every suggestion yourself, and the documents are never stored.
If the technical side interests you, the same material written for professionals is the radiant heating glossary for installers. More answers live in the help center.
Try HeatAlgo for freeA HeatAlgo report follows EN 12831-1 and EN 1264, not ACCA Manual J, and is not accepted for permits or rebates.