Case study: sun path and LiDAR data behind a Queenslander renovation

A Queenslander cottage in Red Hill, Brisbane, is being renovated in 2026. Its owner, a geotechnical engineer and Layered Geo co-founder, used two small Layered Geo datasets for the address, a sun path and a LiDAR terrain line-of-sight package, to settle five design questions that usually rest on rules of thumb: how deep the window hoods should be, whether the ridge view survives them, what glass to specify, where the solar panels go, and how the bathroom skylights will behave. An AI assistant (Claude) did the analysis and built the 3D model from that data. Every answer below is a number for this lot, not a regional average.

The site and the brief

The house is an original Queenslander cottage with a post-war rear extension, on ground at about 24.8 m AHD with the floor at about 26.6 m AHD. The front faces a bearing of 7.8°, so the long side walls face almost due west (277.8°) and east (97.8°). A ridge through Paddington and Red Hill rises to the west.

The brief was typical of a character-house renovation: cut the summer afternoon heat through the west sash windows without losing winter sun, keep the look traditional, keep the view of the ridge, add rooftop solar without putting panels on the street-facing roof, and bring daylight into two internal bathrooms.

The data

Sun path for the site. Sun bearing and height every 10 minutes on the 21st of each month, a monthly summary of sunrise, solar noon, noon sun height and sunset, and a sun path chart as a PDF.

Terrain line-of-sight package. Built from the Brisbane 2019 1 m LiDAR bare-earth ground model: radial ground profiles every 1° from bearings 220° to 330°, out to 1 km, and the western skyline as a table giving, for each bearing, the angle above horizontal, distance and height of the highest ground.

Both were combined with the owner's CAD floor plan, which sits on the MGA56 survey grid, so true wall directions came from the drawing and not from a compass or a street map.

Decision 1: how deep should the window hoods be?

Question. Four new timber hoods are going over the west and east sash windows. Does a deeper hood earn its extra projection?

Method. Sun was traced across each window pane every 10 minutes, past the hood edge and its side palings, using clear-sky sunlight levels.

Result. For one west window on 21 December, no hood admits about 3.96 kWh of sun heat a day, peaking at about 885 W around 4 pm. The standard 565 mm hood, set with its edge just above the window head, cuts that to about 2.28 kWh, a reduction of more than 40%. A 750 mm hood reaches about 1.99 kWh. In midwinter both hoods leave about 2.1 kWh a day against 2.5 kWh unshaded, so roughly 84% of the winter sun is kept.

On a west wall the late sun arrives low, under any overhang, so extra depth buys little. The owner chose the traditional 565 mm proportion at a 40° pitch and accepted about 0.3 kWh a day more heat in midsummer.

Decision 2: will the ridge still be visible?

Question. Can someone inside look up through the west windows and still see the ridge line under the hood?

Method. The LiDAR skyline was compared with lines of sight for a standing person 1.5 m back from the glass and a seated person 2 m back.

Result. The nearest ridge is 210 to 380 m away at 42 to 56 m AHD, sitting 2.8° to 5.3° above horizontal and about 5° up from the west windows. Mt Coot-tha and Enoggera Hill are hidden behind it. The ridge stays well clear of the hood edge from both positions, so shading and view are both achieved. A second view, south-west from the study, was checked the same way.

The same skyline also sets the real sunset. On 21 December the sun drops behind the ridge at about 6:17 pm, against an astronomical sunset of 6:44 pm. On 21 June it is about 4:33 pm against 5:04 pm. The ridge removes the last half hour of the lowest west sun in summer, which the hood sizing took into account.

Decision 3: what glass?

Question. With hoods fixed at the traditional depth, what should the glass do?

Method. The residual heat through the shaded window, from the hood analysis, set the target.

Result. Neutral low-E solar-control glass with a solar heat gain coefficient of about 0.5, for example 6.38 mm laminated. The sashes have no cords or weights, so the practical checks are rebate depth and sash weight.

Decision 4: where do the solar panels go?

Question. Can the panels stay off the street-facing cottage roof without a real loss of output?

Method. Every panel position on the 5° rear extension roof, which falls to the back, was tested against the site sun path for shading by the taller cottage roof and by the ridge.

Result. Shading loss is under 1%, and orientation loss is about 3% against flat panels. Seventeen 440 W panels, about 7.5 kW, fit around the skylights and should produce about 11,000 kWh a year, from about 18.5 kWh a day in June to about 40 kWh a day in December. The house will have a 3-phase supply, so the inverter sits within Energex's 10 kVA per phase limit.

Decision 5: how will the skylights light the bathrooms?

Question. Will the bathroom skylights give harsh direct sun or soft light?

Method. The house was modelled in 3D from the drawings, with the LiDAR terrain to the west as a mesh. A date picker and time slider move the sun and cast live shadows through the windows and skylights. The sun position code was checked against the Layered Geo sun track: bearing within 0.01° all day, and height within about 0.5° near the horizon, where bending of light in the atmosphere is hardest to model.

Result. In midsummer, direct sun only reaches the bathroom floors from about 9 am. Before then the skylight void, about 1 m deep, keeps the low morning sun on its own sides and passes soft light into the room. At midwinter noon the sun is only about 39° up and never reaches the floor. The owner saw this before anything was built.

Key numbers

Summer heat through one west window, no hood	3.96 kWh a day, peak about 885 W
With the 565 mm hood	2.28 kWh a day (over 40% less)
With a 750 mm hood	1.99 kWh a day
Winter sun kept with either hood	about 84%
Ridge above horizontal from the west windows	about 5°
Sun behind the ridge, 21 December	6:17 pm (astronomical sunset 6:44 pm)
Solar array	17 x 440 W, about 7.5 kW
Shading loss / orientation loss	under 1% / about 3%
Estimated solar output	about 11,000 kWh a year
Sun model check against Layered Geo data	bearing within 0.01°

Limits of the analysis

The terrain is bare earth only. Trees and neighbouring buildings were not modelled, so real shading will be somewhat greater and the view somewhat more obstructed than shown. Window heat uses clear-sky sunlight. Solar output uses Bureau of Meteorology long-term monthly averages and typical system losses. Both are design estimates, not monitored figures. Room sizes and roof geometry come from the drawings and should be confirmed on site.

What's next

Two things. First, adding trees and buildings from a LiDAR surface model, which would refine the shading and view checks. Second, offering this as a standard Layered Geo site report. The inputs are small and inexpensive, a sun path and a strip of bare-earth LiDAR, yet they fed five separate decisions and came back within the design conversation, going straight into drawings, a cutting list and a model the owner could explore. The same method applies to any address where Layered Geo holds LiDAR terrain.

The sun path chart and tracks, and the LiDAR elevation grid, come in a Layered Geo site export. To take in a skyline like this one, draw the export area out to the ridge instead of ordering the lot alone.

About this article. Published by LayeredGeo. It is general information about how property and ground conditions are assessed in Australia, not engineering, planning, legal or financial advice, and it is not specific to any property. Check anything that matters against the source dataset or a suitably qualified professional before you rely on it. If you spot something wrong, tell us at hello@layeredgeo.com.au and we will fix it.

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