Facade solar analysis is the process of modelling how direct beam, diffuse and reflected solar radiation strike each elevation of a building across the whole year, then using that data to specify glazing, shading and orientation so the envelope controls heat gain, glare and daylight before the mechanical system is ever sized. In short, it converts an aesthetic elevation into a performance brief: it tells you which facade needs a low-SHGC unit, which can carry bright high-VLT vision glass, and exactly where external shading earns its cost. For any commercial or high-rise project in Hyderabad's hot composite climate, it is the single most cost-effective decision on the entire envelope.
This is not an academic exercise. At roughly 17.4 degrees North, Hyderabad's west and south-west elevations take punishing low-angle afternoon sun from spring through the pre-monsoon peak, while north glazing can run generous for daylight with almost no penalty. Running the study early, at concept rather than tender, lets you lock a shading geometry and a glazing family that survive value engineering, ECBC review and the MEP cooling-load calculation without a redesign. It is the difference between a facade that is engineered and one that is merely drawn.
This guide covers what the analysis actually delivers, how orientation behaves at Hyderabad's latitude, how to turn the results into a defensible glazing schedule, indicative costs in Indian rupees, and the common mistakes that quietly undo a good model. If you are already at buildable details, our glass facade work and structural glazing teams across Hyderabad and Secunderabad can translate a solar study into shop drawings, fabrication and installation.
What facade solar analysis actually tells you
A proper study gives you elevation-by-elevation data you can specify against, not a single glass type for the whole building. It answers, in numbers, where the heat is, when it arrives and how much daylight you can safely harvest. The deliverables you should ask for or produce are:
- Annual and peak solar irradiance per elevation (kWh/m2/yr and peak W/m2), so cooling loads are attributed to the facade rather than a blanket assumption.
- Sun-path and shadow studies at the solstices and equinoxes, used to size horizontal overhangs and vertical fins geometrically instead of by eye.
- Direct-sun-hours and glare mapping on the floorplate to locate deep-perimeter discomfort and screen-glare zones near workstations.
- Daylight autonomy (sDA) and useful daylight illuminance (UDI) to justify VLT and cut artificial lighting load for IGBC or GRIHA credits.
Tools range from SketchUp with Sefaira and Rhino with Ladybug and Honeybee up to full IES-VE or DesignBuilder. The choice of engine matters far less than feeding real Hyderabad EPW weather data instead of a generic warm-climate profile, because the local diurnal swing and monsoon cloud cover materially change the answer. Treat the output as a design tool, not a report to file: it should change your elevations, not decorate a submission.
Reading orientation in the Hyderabad sun
At roughly 17.4 degrees North, the Hyderabad sun sits high overhead for much of the day but swings to steep, low angles on the east and west, which is exactly where glazing suffers most. The same latitude governs Secunderabad, the wider Telangana plateau and coastal Andhra Pradesh, so the orientation logic below travels across a regional portfolio with only minor humidity adjustments for the coast.
- West and south-west (the worst case): low afternoon sun from March to June defeats overhangs entirely. Specify low-SHGC selective glass plus vertical fins or a deep reveal, or simply reduce vision-glass window-to-wall ratio here.
- East: strong morning gain, but it lands on a slab that has cooled overnight, so vertical shading or a moderate SHGC usually suffices.
- South: high-angle summer sun is easily cut by a horizontal overhang sized from the summer solar altitude, making this a good candidate for generous, well-shaded vision glass.
- North: minimal direct beam year-round, so carry high-VLT glass here to maximise daylight and views with essentially no heat penalty.
The practical takeaway is that a building in Hyderabad rarely wants one glass. It wants a family of units tuned per face, and the west elevation almost always writes the shading brief for the whole envelope. You can see how this plays out across real elevations in our recent projects.
Turning results into a glazing specification
Facade solar analysis lets you write numbers on the drawing instead of adjectives. Three glazing performance figures should appear explicitly on your glazing schedule, and a supplier's data sheet should confirm all three before any unit is ordered:
- SHGC (Solar Heat Gain Coefficient): the fraction of solar energy transmitted through the unit. Lower cuts cooling load directly. Target tighter values around 0.25-0.30 on west and south, and relax toward 0.40+ on north.
- VLT (Visible Light Transmittance): drives daylight and glare. Pair a low SHGC with adequate VLT so interiors read bright, not cave-like.
- U-value: conductive transfer. It matters more for perimeter comfort and the winter and monsoon shoulder than for peak solar in this climate, but it still belongs on the schedule.
Aim for a Light-to-Solar-Gain ratio (VLT divided by SHGC) above about 1.25 by choosing a spectrally selective, high-performance coating rather than a blanket dark tint. A dark tint kills daylight and glare together but throws away the free light you already paid for. Note too the SHGC-versus-Shading-Coefficient distinction: SC is approximately SHGC divided by 0.87, so always confirm which metric a supplier quotes before comparing units. For unitised and captured systems, remember that the glass sits inside a thermally broken aluminium frame whose own U-value and air-tightness affect the whole-unit performance you just modelled, which is why frame selection belongs in the same conversation as the glass, not after it.
Shading design, ECBC code and the trade-off path
Shading is the cheapest solar tool you have, and analysis is what sizes it defensibly instead of by eye. A 600 mm overhang that is 200 mm too shallow at the design hour is worthless; the sun-path study tells you the exact projection you need at the exact time gain peaks.
- External shading stops radiation before it reaches the glass, making it roughly 3-4x more effective than internal blinds, and it is preferred wherever facade access and maintenance allow.
- Size horizontal projections from the local solar altitude at the design hour; size vertical fins from the solar azimuth to catch low east and west sun that overhangs miss.
- ECBC 2017 sets prescriptive envelope limits, with SHGC and U-value ceilings that tighten as window-to-wall ratio rises. Solar analysis unlocks the whole-building or trade-off compliance route, letting a higher WWR or richer daylight on one elevation be offset by shading and better glass elsewhere.
- Feed per-elevation peak W/m2 to the MEP consultant so cooling is sized to the analysed facade, and route your daylight results toward IGBC, GRIHA or LEED credits.
Where shading elements are structural, such as projecting fins, canopies, brise-soleil or spider-supported blades, the connection design becomes part of the facade engineering rather than an afterthought. This is exactly the interface where a coordinated structural glazing approach pays off, because the same team that models the sun can detail the bracket that carries the shade. If you want a study translated into a live glazing and shading schedule, you can get a free quote against your drawings.
Costs and payback in Indian rupees
The economics almost always favour analysis, because envelope decisions are locked early and cascade into decades of running cost. The following are indicative Hyderabad-market figures, subject to scope, floor count and specification:
- A concept-stage facade solar study for a mid-rise commercial building typically runs Rs 1.5-6 lakh depending on floor count and the level of daylight and glare detail required.
- High-performance double-glazed units with a selective low-e coating cost roughly Rs 850-1,600 per sq ft supplied and installed, versus Rs 350-600 per sq ft for ordinary tinted single glazing or a basic DGU.
- External aluminium fins or a horizontal shading system add roughly Rs 400-900 per sq ft of shaded facade, but the offsetting glass downgrade and chiller savings usually recover the cost.
- Structural glazing and unitised curtain wall systems typically fall in the Rs 650-1,400 per sq ft band depending on glass, framing and wind zone, before shading.
- Correctly sizing cooling to the analysed facade instead of a conservative blanket load routinely removes 10-20 percent of installed tonnage, often one whole chiller module on a mid-sized tower, worth several tens of lakhs in capital plus a permanent energy saving.
The lesson is that the study is a rounding error against the glazing and MEP packages it optimises. Spending on analysis to under-spend on glass, shading and plant is the correct order of operations, and it is the order that survives value engineering intact.
Pros, cons and when it is worth it
Facade solar analysis is not free and not instant, so it is worth being honest about the trade-offs before you commit a fee line to it.
- Pros: it cuts peak cooling load and lifetime energy cost, produces defensible ECBC and green-rating documentation, prevents costly late glass upgrades, improves occupant comfort and daylight, and gives the client a facade that is quiet, bright and cheap to run.
- Cons: it adds a modest concept-stage fee and a short programme item, it depends on good weather data and an honest model, and a study filed and ignored delivers nothing.
- Clearly worth it: any air-conditioned commercial, IT, hospital, hotel or high-rise residential building; any project chasing IGBC, GRIHA or LEED; any facade with significant west or south-west glazing; and any scheme where WWR is above roughly 40 percent.
- Marginal: small low-rise buildings with modest glazing, deep verandahs or naturally shaded sites, where rule-of-thumb glazing and generous overhangs may already be close to optimal.
For most serious buildings in Hyderabad, Secunderabad and across Telangana and Andhra Pradesh, the question is not whether to analyse but how early, because the value of the study falls sharply the closer you get to tender.
Common mistakes that quietly undo a good model
A perfect model on the wrong assumptions still produces the wrong facade. These are the errors we see most often on projects that arrive with a study already done:
- Using generic warm-climate weather data instead of a real Hyderabad EPW file, which distorts both peak gain and the monsoon shoulder.
- Specifying one SHGC for the whole building, which either overheats the west or needlessly darkens the north.
- Chasing SHGC alone and ignoring VLT, ending up with a dark, glare-prone interior that burns lighting energy in daytime.
- Sizing overhangs by eye rather than from the solar altitude at the true design hour, so the shade misses the sun when it matters.
- Modelling the glass but forgetting the frame, gaskets and hardware, so the built whole-unit performance never matches the schedule.
- Running the study at tender, when orientation and WWR are already locked and the only remaining lever is an expensive glass upgrade.
Avoiding these keeps the model honest, and an honest model is what lets you commit to a glazing family and a shading geometry that hold through construction. Our broader services are structured so the same team that reads the analysis also details the frame, gaskets and fittings that deliver it.
Process, timeline and a concept-stage checklist
A typical study runs alongside early design and takes about two to four weeks from a workable massing model, longer if detailed glare and daylight-credit mapping is required. The sequence is: build or import the massing, apply real Hyderabad EPW data, run irradiance and sun-path studies per elevation, iterate glazing and shading options, and finally hand orientation-specific targets to the glazing schedule and the MEP brief.
Use this as a gate before you lock WWR and hand elevations to tender:
- Run the study on real Hyderabad EPW weather data at concept, not at tender.
- Attribute solar loads per elevation in kWh/m2 and peak W/m2, not per building.
- Set orientation-specific SHGC and VLT targets and record them on both the elevations and the glazing schedule.
- Prove the shading geometry against solstice and equinox sun paths, especially the west afternoon condition.
- Coordinate results with MEP cooling loads and your green-rating daylight credits before finalising WWR.
- Confirm frame, hardware and gasket selections match the modelled whole-unit performance, not just the glass.
Clear every line before the design freezes and the analysis will have done its job: an envelope that is quiet, bright, code-compliant and cheap to cool for its whole life. Hakimi Aluminium and Glass provides design-assist, shop drawings, fabrication and installation for architects across Hyderabad, Secunderabad, Telangana and Andhra Pradesh, and can turn your solar study into buildable glazing and shading details.
