Why does a home app need to know where the house is on the map?
A floor plan can be drawn without knowing where the house is. But as soon as the app needs to calculate sunlight, shadows from neighbours or noise from a road, it needs to know two things: the position, and which way the house faces. That is not the same question.
Short answer: the position on the map tells the app WHERE on earth the house stands — which gives access to latitude, longitude and local map data such as roads, neighbours and green spaces. The north direction tells the app WHICH WAY the house itself faces. The two are used together for everything to do with light, sun and orientation: sun studies, shadow calculations, "which room gets morning sun" and assessments of the surroundings. Without them, the floor plan, the takeoff and the 3D model still work perfectly fine — it is only the light-related features that are missing their foundation.
Two different questions that often get confused
"Where is the house" and "which way does the house face" sound like the same question, but they each answer a different part of a sun calculation. The position — latitude and longitude — determines how high the sun stands in the sky on a given date and time. A home in Northern Europe sees the sun stand lower in winter than a home closer to the equator, even at the same date and time. The north direction determines how that sun path lines up against the house's own walls and windows: a window facing south gets quite different light from one facing north — but the app can only know which window is which if it knows the house's own orientation.
What can be calculated without knowing the location?
A great deal. A floor plan with correct measurements, a takeoff for a contractor, a renovation budget, and a 3D model of the building's shape — none of them require knowing where the house sits on the globe. It is pure geometry: lengths, areas, volumes. You can use a home app fully for all of that without ever placing the house on a map.
What requires the location is everything that involves the sun's position relative to the building — and, following on from that, everything to do with the building's relationship to its surroundings: how close is the neighbour, where does the road run, what do you actually see from each window.
How do you find the house's north direction?
There are three common ways, depending on how precise you need to be:
- A map with a north arrow. Most map apps and map data show north pointing up. Place the house correctly on a map and rotate it to line up with the actual buildings around it, and the north direction follows automatically.
- A compass app, or the phone's built-in compass. Stand with your back against an outer wall and read which cardinal direction that wall faces. It's quick, but phone compasses can be inaccurate near metal and electronics in the building — measure outside if you can.
- The sun's position at a known time. At solar noon (local solar time, not the clock's 12) the sun stands due south in the northern hemisphere. See sunlight hitting a particular wall around midday, and you know that wall faces south.
For a sun calculation meant to be relied on seriously, the map method is the most trustworthy, because it doesn't depend on a single momentary reading but on the house's actual position among the surrounding buildings.
What is the location used for besides sunlight?
Once the app knows the house's position, it can link the building to what surrounds it:
- Distance to roads and rail lines — relevant for assessing noise.
- Distance to neighbouring buildings — relevant for overlook and shadow from the house next door.
- Direction to schools, shops and other everyday destinations — relevant to whether the location actually suits everyday life.
- Views — which direction has the best outlook, and which room benefits from it.
None of these can be worked out from the building's geometry alone. They require the app to know where on the map the house stands, and to be able to compare that with the map data around it.
Should the house be placed precisely, or is roughly enough?
It depends on what the figure is used for. For a general sense of "does the living room get afternoon sun", a placement within a few metres and a north direction within a couple of degrees is more than enough — the sun's angle changes slowly over such short distances. For a calculation meant to decide whether a specific window is shaded by a particular neighbouring building at a particular time, precision matters more: an error of 10 degrees in the north direction can shift the shadow edge half a metre along the façade.
The practical rule: use the map method and adjust the house until it lines up with the actual buildings around it on the map. That usually gives a precision that is good enough for any practical use.
Can you place the house without knowing the exact address?
Yes. Most map solutions let you either search for an address or find the point directly on the map by zooming in and dragging the house into place visually. If the house hasn't been built yet, or the address isn't registered, the second option is the only route — and it works just as well for the purpose.
What HouseSense does
In HouseSense you place the house's footprint on a map and rotate it until it matches the building as it actually sits. That position and orientation are then used for the sun study, the daylight profile, and the surroundings assessment (distance to roads, neighbours, view and everyday destinations) — all features that would otherwise have nothing to calculate from. The rest of the app, from floor plan to 3D model, works whether or not the house is ever placed at all.
What if you change your mind about the placement afterwards?
Placement is not a one-time decision. Move the house on the map or correct the north direction later, and every feature that uses it — sun study, daylight profile, surroundings — updates immediately to the new figures. There is no need to rescan or re-measure anything because the placement changes; it is purely geographic information laid on top of a building that has already been measured.
Short decision list
- Do you only need the floor plan, measurements and 3D shape? Skip the placement — it makes no difference here.
- Do you need to know when a room gets sun? Place the house and find the north direction before you trust the result.
- Do you need to assess noise, overlook or the view? Same thing — the placement is the precondition, not an extra nicety.
- Unsure about the north direction? Use the map and the actual neighbouring buildings as your reference, rather than a single compass reading.