Owner's design management · Environmental analysis
Thirty-one Autodesk Forma runs over the current massing, read against the Yanbu station wind record and a calculated sun path. What the model shows, what it means for the roof, the pool deck and the terraces, and what to build.
Across the whole site at 1.75 m, on both comfort scales, in every direction case. Nothing at grade needs fixing.
The stepped plan throws a large calm zone over the first-floor roof deck and the pool deck. The building's shape is already doing the work at that level.
Every roof surface reads red — the band above 8 m/s — on both scales and in every wind direction tested. The roof restaurant, lounge and bar all sit in it.
The station record peaks at 7.7 m/s at 16:00; the sun is then 42° up at 280°. Same hour, same direction, and it is the hour the terraces exist for.
NEN 8100 and Lawson LDDC scales; whole-rose and single-direction cases (N 0°, NW 315°); ground and roof surfaces; 1.75 m above each surface.
21 June, 00:00–24:00, ground and geometry.
Summer solstice, equinox, winter solstice × 09:00 / 12:00 / 15:00.
Facade and geometry daylight potential across the massing.
Surfaces filtered 0–75°; annual incident energy and panel yield estimate.
Telling sheltered from exposed, finding the corners and edges that accelerate, and ranking one design option against another. On those questions the runs are consistent across seventeen wind cases and two independent comfort scales, which is the strongest evidence this stage can produce.
Forma's wind rose puts the dominant sector in the west. That agrees with the 14-year Yanbu station record (Rehman), which gives W and WNW about 47 % of hours, N about 15 % and NNW about 10 % — roughly 72 % of the year in the W-through-N arc. The directional input is right; it is the speed magnitude that carries the uncertainty.
Drive the model from the Yanbu station rose rather than GWA, or commission a short site measurement, before the screen heights are fixed. Wind-tunnel or validated CFD only if the roof venue is contested. That is a stage-appropriate step, not a redesign.
The sun-hours run answers the first question plainly. On the longest day the open ground, the podium and every roof surface receive nine hours of direct sun or more. The only purple — genuine shade — is the north face of the tower and the strip the building casts on itself. Nothing on this site is shaded by anything except the building, so every square metre of shade on the terraces has to be built.
The calculated sun path fixes the geometry that shade has to answer. The two numbers that govern the design are the June sunset azimuth of 293° and the December sunset azimuth of 242° — a 51° swing. The sun sets over the water in both cases, which is the reason the hotel faces west, but it sets in a different place in summer than in winter and no single fixed screen catches both.
At solar noon the sun is 87.7° up on 21 June and 42.5° up on 21 December. A flat horizontal canopy is almost perfectly efficient in summer and almost useless in winter — which is the correct behaviour for a Red Sea resort, where shade is wanted in both seasons but the summer load is the one that matters.
| Date | Sunrise | Sunrise azim. | 09:00 alt / azim. | 12:00 alt / azim. | 15:00 alt / azim. | Sunset | Sunset azim. | Daylight |
|---|---|---|---|---|---|---|---|---|
| 21 June | 05:11 | 60.5° ENE | 42.3° / 79.5° | 83.2° / 94.0° | 55.7° / 276.8° | 18:48 | 293.3° WNW | 13 h 38 |
| 22 September | 05:55 | 87.1° E | 36.0° / 108.5° | 65.6° / 167.5° | 44.6° / 244.2° | 18:04 | 268.5° W | 12 h 08 |
| 21 December | 06:40 | 112.9° ESE | 21.1° / 129.8° | 42.1° / 172.0° | 29.5° / 221.1° | 17:19 | 241.8° WSW | 10 h 38 |
Nine frames — three dates, three times. Read across a row and the day turns; read down a column and the season turns. The pattern is consistent and it has one clear consequence.
In the morning the building throws its shadow west and north-west, across the sea frontage and the arrival side. By noon the shadow has collapsed to almost nothing in June and stretched north in December. By 15:00 it has swung east, inland, across the annex and the car park — away from everything the guest uses.
So the terraces, the pool deck and the roof are shaded by the building in the morning, when they are cool and lightly used, and fully exposed from noon to sunset, when they are busy. The self-shading works at exactly the wrong time of day. This is not a fault in the massing — it is the price of facing the sunset — but it means the afternoon shade is entirely a landscape and structure problem, not a massing one.
| Time | Altitude | Azimuth | Profile angle | What it means on the deck |
|---|---|---|---|---|
| 14:00 | 69.3° | 272.8° | 69.3° | Sun almost overhead — a flat canopy shades everything |
| 15:00 | 55.7° | 276.8° | 55.9° | Still above the trellis cut-off |
| 16:00 | 42.1° | 280.5° | 42.6° | Trellis stops working — sun starts coming in under it |
| 17:00 | 28.8° | 284.6° | 29.6° | Full glare across the tables; wind at its annual peak |
| 18:00 | 15.7° | 289.1° | 16.5° | Low sun straight down the terrace |
| 18:30 | 9.3° | 291.6° | 9.9° | Sunset over the water — the view the hotel is sold on |
Seventeen runs, two comfort scales, several single-direction cases. They all say the same three things.
One: the ground plane passes. Zero per cent of the site at 1.75 m falls in the uncomfortable band, on either scale, in any case tested. On the NEN 8100 setting 21–22 % of the ground is sitting and standing grade and 77–79 % is strolling and walking. On the stricter Lawson LDDC setting the sitting and standing share drops to 5–6 % and walking rises to 93–95 %, but the uncomfortable share stays at zero. The drop between the two scales is a band-edge artefact, not a change in the wind: Lawson groups sitting and standing below 4 m/s where NEN's equivalent grouping sits at 5 m/s.
Two: the podium shelters itself. In every plan view there is a broad pale-green plateau — the sitting band — across the central podium, held there by the tower mass upwind of it. That plateau covers the first-floor roof deck and the pool deck. The stepped, folded plan is not only a view device; it is producing the calm air over the amenity level, for free, in the dominant wind direction. This is the design working, and it is the single most valuable thing in these runs. It should be protected in any further massing change: opening the north-west shoulder of the tower would drain it.
Three: the top roof fails. Every roof surface in every run is red. Not marginal — solid red, the band above 8 m/s at 5 % exceedance, on both scales, in the whole-rose case and in the single-direction cases. The roof restaurant, the roof lounge and the sunset bar are all planned in it. There is nothing upwind of a roof at 34 m to slow the flow, and the parapet edge accelerates it further.
The station record sharpens the problem. Yanbu's wind is not steady through the day: it runs at about 2 m/s at dawn and peaks at about 7.7 m/s at 16:00, a classic afternoon sea-breeze build. The sea breeze on this coast does not arrive as a separate circulation — it reinforces the prevailing north-westerly. So the windiest hour of the day comes from the same direction as the prevailing wind, and it is the same hour the sun is low in the west and the terraces are filling up.
| Run | Scale | Sitting / standing | Strolling / walking | Uncomfortable |
|---|---|---|---|---|
| Whole rose, aerial | NEN 8100 | 22 % | 77 % | 0 % |
| Whole rose, plan | NEN 8100 | 21 % | 79 % | 0 % |
| NW 315° (17 % of hours) | NEN 8100 | 22 % | 77 % | 0 % |
| Whole rose, site | Lawson LDDC | 6 % | 93 % | 0 % |
| Whole rose, oblique | Lawson LDDC | 5 % | 95 % | 0 % |
The solar run is the one unambiguously good piece of news. Ten thousand four hundred and nine square metres of the building sit between horizontal and 75°, and they receive about 2,000 kWh/m² a year — 20.9 GWh of incident energy across the envelope. That is a Red Sea number; it is roughly double what the same array would collect in northern Europe.
Forma's own estimate assumes 60 % surface coverage and 15 % module efficiency and returns 6,246 m² of panel producing 1.52 GWh a year. The 15 % figure is Forma's conservative default and is well behind the market: commercial monocrystalline modules in 2026 sit around 21 %. On the same area and the same irradiance that scales to about 2.1 GWh a year. The difference is worth stating clearly because it changes the payback case, not the design.
The same sun that makes this worth doing is what the roof has to be protected from. The roof plane takes nine hours and more on the longest day, at about 2,000 kWh/m² a year. Every square metre of roof that is neither under panel nor under shade structure is a cooling load.
| Quantity | Value | Note |
|---|---|---|
| Surface selected (0–75°) | 10,409 m² | Forma filter |
| Average incident energy | 2,000 kWh/m²/yr | Across the selected surface |
| Total incident energy | 20,900,000 kWh/yr | The resource, not the yield |
| Assumed coverage | 60 % | Forma default |
| Panel placement area | 6,246 m² | Forma output |
| Yield at 15 % efficiency | 1,520,000 kWh/yr | Forma output, conservative |
| Yield at 18 % efficiency | 1,820,000 kWh/yr | Scaled |
| Yield at 21 % efficiency | 2,130,000 kWh/yr | 2026 market-typical module |
Zero per cent uncomfortable across the site at 1.75 m, in all seventeen runs. 21–22 % sitting/standing grade under NEN 8100, 5–6 % under Lawson LDDC, the balance strolling and walking.
Nothing at grade requires mitigation. Record the result in the submittal pack; it is a supporting argument, not a problem.
A continuous sitting-grade zone forms over the central podium in every run, produced by the tower mass standing upwind in the dominant W–NW sector. The first-floor roof deck seating and the pool deck both fall inside it.
The shelter depends on the tower keeping its bulk on the north-west shoulder and on the stepped plan holding its fold. Opening that corner or lowering that wing would drain the calm pocket.
Put the long-dwell seating — the lounge groups, the daybeds, the dining tables — in the green plateau, and the circulation, the bar counter and the pool edge in the yellow. Match the furniture to the band rather than spreading one layout across both.
Solid red on both comfort scales, in the whole-rose case and every single-direction case: the band above 8 m/s at 5 % exceedance. The roof restaurant, the roof lounge and the sunset bar are all planned inside it. At 34 m there is nothing upwind to slow the flow, and the parapet edge accelerates it.
A screen of 40–50 % porosity, 1.8–2.1 m above finished deck, set back from the parapet rather than sitting on it. Porous, not solid: a solid barrier throws a separation bubble and re-accelerates the flow a few metres downstream, which is worse than no screen at all, while a 40–50 % porous barrier gives usable shelter for roughly ten to fifteen times its height with far less turbulence. Target is to bring the seating zone from above 8 m/s down to the 2.5–4 m/s standing band — moderation, not elimination. This is the element that solves the wind; the trellis in finding 4 solves the sun. Two problems, two elements.
Vertical adjustable louvres on the sunset arc: angled open for the view in calm conditions, closed down in the afternoon peak. It costs more than a fixed screen and it is the difference between a roof venue that trades every evening and one that closes when it blows.
Keep the parapet edge for standing and photographs; put the dining tables one structural bay in from it, behind the screen line. Free, and it recovers most of the comfort on its own.
The roof takes nine hours and more of direct sun on 21 June, at a solar-noon altitude of 87.7°. The covered restaurant needs a canopy that works from noon to about 16:00, which is when the profile angle on a west-facing deck falls through 42°.
Slats about 200 mm deep at about 170 mm clear spacing — roughly 370 mm centres, a depth-to-gap ratio of about 1.2 — cut off all direct sun above a 40° profile angle. That covers solar noon through to roughly 16:15 in June, and the whole of the winter afternoon. Timber or timber-faced, up-lit from the beams so nothing is lit from above.
From 16:00 the sun drops under any horizontal canopy — profile angle 42.6° at 16:00, 29.6° at 17:00, 16.5° at 18:00. That is exactly the service period. The west screen from finding 3 is what catches it. One element, two jobs: it is the single highest-value piece of structure on this project.
The trellis is a south- and west-facing substrate already in the sun for nine hours. Integrating panels into the slats does shading and generation on one structure and one foundation. Coordinate the slat module with the panel module before the structure is fixed, not after.
The pool deck sits in the sheltered podium plateau, so it starts from a better position than the roof. But it has no shade at all after noon and it takes the afternoon sea breeze across its west and north-west returns.
Shade the dwell zones and leave the pool itself open: shading the water kills the reason people are in it and does nothing for comfort. Same slat geometry as the roof restaurant so the two read as one family.
Date palm and olive in stone troughs along the returns. Trees are the right porosity by nature — a planted line performs as a porous barrier without the separation problem a wall creates, and it does not need to be detailed for wind load the way a screen does. Aim for roughly 50 % visual porosity and a 1.8–2.5 m canopy base so the shelter works at seated and standing level.
Shelter the edges, not the view. The windbreak line belongs on the returns and the north-west shoulder; the central corridor to the water stays clear. Sheltering the whole perimeter would trade the hotel's main asset for a comfort band it does not need at this level.
The alfresco terrace runs along the west elevation under the floor above, so it is already shaded. Its problem is the same 16:00 flow, arriving along the terrace rather than across it.
Stone troughs at 1.2–1.8 m planting height, placed across the upwind end of the terrace rather than along its length. That height shelters seated diners and the table settings — candles, linen, menus, the things that actually fail first — without cutting the standing sight line to the water.
Loose troughs, not built planters, so the line can be re-set for events and adjusted once the terrace is in use and the real behaviour is known. Desert grasses and olive rather than dense hedge: the flow should be slowed and broken, not stopped.
The colonnade bays funnel the flow. A planter in alternate bays breaks the channel without closing the terrace.
The roof plane receives nine hours and more on the longest day and about 2,000 kWh/m² a year. Every square metre not under panel or structure is a direct cooling load on the floor below.
This is the cheapest cooling-load reduction available on the project and it is invisible in the drawings, which is why it gets value-engineered out. Fix the U-value target now and carry it through the BIM model so it survives the cost exercise.
Any roof area that is neither PV nor terrace gets a high solar-reflectance finish. It costs nothing over a standard finish at specification stage and it lowers both the cooling load and the surface temperature the plant has to sit in.
Three trades, one plane, and the PV and trellis fixings puncture the waterproofing. Draw the roof build-up as a single coordinated section before any of the three is procured.
6,246 m² of panel area at 60 % coverage. Forma returns 1.52 GWh a year at its conservative 15 % default; at a 2026-typical 21 % module the same area yields about 2.13 GWh.
The 40 % uplift over Forma's default is the difference between a nice-to-have and a funded scope. Re-run the commercial case on the corrected figure before the decision is taken.
Inverters, DC routing, roof penetrations and maintenance access all need space that the roof restaurant and the pool plant are also competing for. Allocate it on the roof plan at this stage; it cannot be found later.
See finding 4. The shade structure the terraces need anyway is the cheapest mounting system on the project.
At 16:00 on 21 June the profile angle on the west elevation is 42.6°, falling to 16.5° by 18:00. A 1.2 m balcony overhang shades about 1.3 m of the facade at 16:00 and effectively nothing after 17:00. Every key in the tower faces this.
The perforated screen on the west elevation is the element actually controlling the low sunset sun; the overhang is not. Confirm its open area and its coverage against the room-by-room solar gain, and confirm it is still in the package after the facade cost exercise.
The daylight-potential run shows the recessed balcony returns and the inboard faces reading lowest. Confirm the room daylight factor at those positions before the balcony and screen detail is fixed.
A small red patch appears at the north-west ground corner in one run — a local corner acceleration rather than a site-wide problem, and it does not sit on a main pedestrian route.
Low-cost, low-priority. Worth fixing while the landscape package is open; not worth a design change on its own.
The afternoon wind at Yanbu comes off the water from the W and NW, and it is the sea breeze: marine air, cooler than the air over the land it is replacing. It is not a hot wind. It is the site's main passive cooling asset, arriving too fast.
Screening the terraces to dead calm would remove the convective cooling and make them hotter, not cooler, in the same air temperature. Every screen and planting line in this report is sized to bring speeds down into the 2.5–4 m/s sitting-and-standing band, not to zero. Porosity is the whole point of the porous screen — it is doing two things at once, and losing either one is a failure.
The alfresco terrace, the pool deck and the roof should all be permeable downwind of their screens, so the moderated air keeps moving across the occupied zone instead of stagnating behind the barrier.
These runs are driven by Global Wind Atlas 3.0 — a wind-energy screening dataset with about ±14 % mean absolute speed error and no urban canopy model — and Forma resolves only eight wind directions. Comfort bands are 1.5–2 m/s wide, so the model can tell sheltered from exposed but cannot fix a screen height.
A 14-year hourly record exists for Yanbu (mean 4.63 m/s at 10 m, peak 7.7 m/s at 16:00, W and WNW about 47 % of hours). Using it in place of GWA removes the largest single source of error for a small amount of work, and it is enough to size the screens.
The published Yanbu series runs 1970–1983. It remains the best directional evidence available, but an epoch check against a recent year of airport data is worth the hour it costs.
If the operator or the authority challenges the roof restaurant, that is the point at which the testing is justified — and having it named in the programme now means it can be commissioned without a delay.
Sequenced by what blocks what. The first item sizes the screens and the planting, so it gates the roof and landscape packages; the rest can run in parallel with the current design development.
Everything downstream — screen heights, planting heights, whether the operable louvre is justified — is sized off this. It is a day's work.
Before screens are sizedInsulation, waterproofing, PV fixings, trellis fixings and plant zone on one drawing, before any of the three packages is procured.
With the roof planPool deck returns, alfresco terrace upwind end, north-west ground corner. Loose troughs, roughly 50 % porosity, heights as noted.
With the landscape packageOpen area and coverage against room solar gain and the daylight result. Protect it through the facade cost exercise.
Before facade tenderForma's 15 % default understates the yield by about 40 %. The commercial decision should be taken on the corrected number.
Before the PV decision