{"slug":"stack-height-calculation-cpcb-guidelines","title":"Stack Height Calculation as per CPCB Norms: DG Set, Boiler & SO2 Formula","excerpt":"CPCB stack height formulas with worked examples: DG sets H = h + 0.2√KVA, boiler minimums by steam capacity (9 m to 30 m), and H = 14 Q^0.3 for SO2 — plus when dispersion modelling is required.","date":"2026-06-18","author":"DSTechnoverse","image":"https://images.unsplash.com/photo-1611273426858-450d8e3c9fce?auto=format&fit=crop&w=1200&q=80","category":"Air Quality Modelling","tags":["stack height calculation CPCB","air dispersion modelling","AERMOD","EIA","India"],"content":"Industrial chimneys are not sized by guesswork. In India, the height of a stack is a regulated design parameter that decides how effectively flue gases disperse before they reach the ground where people breathe. Getting it wrong can mean failed consent applications, elevated ground-level pollutant concentrations, and non-compliance with the Central Pollution Control Board (CPCB) norms.\n\n## What Is Stack Height Calculation as per CPCB?\n\nStack height calculation as per CPCB is the process of determining the minimum chimney height required for an industry so that pollutant emissions disperse adequately and ground-level concentrations stay within National Ambient Air Quality Standards (NAAQS). CPCB prescribes formula-based minimum heights linked to emission rate, fuel type, and plant capacity, supplemented by air dispersion modelling for accurate site-specific design.\n\nIn practice, the CPCB approach blends two things: a prescriptive minimum height (a regulatory floor no stack may fall below) and a performance check using scientific dispersion modelling that confirms the chosen height actually protects ambient air quality.\n\n## Why Does Stack Height Matter for Pollution Control?\n\nA stack does not remove pollutants; it disperses them. A taller, well-designed stack releases emissions higher into the atmosphere, giving the plume more room to dilute before it descends to ground level. This lowers the maximum ground-level concentration (GLC) of pollutants such as sulphur dioxide, oxides of nitrogen, and particulate matter.\n\nThe right height matters because:\n\n- It keeps ground-level pollutant concentrations within NAAQS limits.\n- It reduces localised hotspots near residential areas, schools, and hospitals.\n- It helps avoid downwash effects from nearby buildings and terrain.\n- It is a mandatory condition for Consent to Establish and Consent to Operate under the Air Act, 1981.\n- It supports approvals under the EIA Notification 2006 and Environmental Clearance from MoEFCC or SEIAA.\n\nAn undersized stack can trap emissions in building wakes, causing high concentrations right at the plant boundary. An oversized stack wastes capital and increases structural and wind-load costs. Calculation is about finding the technically correct height, not simply the tallest one.\n\n## What Is the CPCB Basis and Formula for Stack Height?\n\nCPCB provides emission-based criteria for minimum stack heights, differentiated by industry sector and pollutant load. Two widely referenced bases are used across Indian industries.\n\nFor sulphur dioxide emissions, a commonly cited CPCB relation links stack height to the emission rate of SO2:\n\nH = 14 multiplied by Q raised to the power 0.3\n\nHere H is the stack height in metres and Q is the SO2 emission rate in kilograms per hour. This gives a minimum height that scales with the pollutant load.\n\nFor thermal power plants, CPCB and MoEFCC specify minimum heights tied to generating capacity. For particulate-emitting industries, minimums are often defined relative to nearby building height, typically requiring the stack to rise a set distance above the tallest adjacent structure to avoid aerodynamic downwash.\n\n### Common CPCB Minimum Stack Height Benchmarks\n\n| Source category | Typical CPCB basis | Indicative minimum height |\n|---|---|---|\n| Thermal power plant (up to 200 MW) | Capacity based | Around 220 metres |\n| Thermal power plant (210 to 500 MW) | Capacity based | Around 275 metres |\n| DG set | H = h + 0.2 × √KVA | Building height plus 0.2 × √KVA |\n| Small boiler | Steam capacity based | 9 to 30 metres by tonnes/hour |\n| Process industry with SO2 emissions | Emission-rate formula | H = 14 Q to the power 0.3 |\n| General particulate source | Building-height relative | 5 to 6 metres above tallest nearby structure |\n\nThese benchmarks are indicative. Exact values depend on the specific CPCB or State Pollution Control Board (SPCB) direction applicable to the sector, the fuel, and the location. The formula output is a floor; the final design height is confirmed against ambient impact.\n\n### Stack Height for DG Sets (Diesel Generators)\n\nFor diesel generator sets, CPCB norms under the Environment (Protection) Rules give a direct formula rather than a modelling exercise:\n\n**H = h + 0.2 × √KVA**\n\nwhere:\n\n- **H** is the total stack height above ground, in metres\n- **h** is the height of the building in which the DG set is installed, in metres\n- **KVA** is the total generator capacity of the set, in kVA\n\nThe stack must therefore clear the roof of the generator building by at least 0.2 × √KVA. Worked examples:\n\n| DG set capacity | Building height (h) | 0.2 × √KVA | Minimum stack height (H) |\n|---|---|---|---|\n| 125 kVA | 6 m | 2.24 m | 8.3 m |\n| 250 kVA | 10 m | 3.16 m | 13.2 m |\n| 500 kVA | 10 m | 4.47 m | 14.5 m |\n| 1,000 kVA | 15 m | 6.32 m | 21.4 m |\n| 2,000 kVA | 15 m | 8.94 m | 24.0 m |\n\nTwo practical points come up repeatedly. First, use the capacity of the set the stack serves; where several sets share a common stack, State Pollution Control Boards generally expect the combined capacity. Second, h is the building that houses the generator — if the set sits in an open yard beside a taller block, expect the SPCB to ask for clearance above the adjoining building as well. Confirm the reading with the applicable SPCB consent conditions before fabrication.\n\n\n{{tool:dg-stack-height}}\n\n### CPCB Stack Height Bands for Small DG Sets\n\nThe same norm also groups small generators into bands, so for sets up to 300 kVA the clearance above the roof can be read straight from a table:\n\n| DG set capacity | Minimum stack height |\n|---|---|\n| Up to 50 kVA | Height of the building + 1.5 m |\n| 50 to 100 kVA | Height of the building + 2.0 m |\n| 100 to 150 kVA | Height of the building + 2.5 m |\n| 150 to 200 kVA | Height of the building + 3.0 m |\n| 200 to 250 kVA | Height of the building + 3.5 m |\n| 250 to 300 kVA | Height of the building + 3.5 m |\n\nAbove 300 kVA the height is worked out from the formula. The bands are simply the formula evaluated at the top of each band and rounded up to the next half metre (0.2 × √50 = 1.41 m becomes 1.5 m, 0.2 × √300 = 3.46 m becomes 3.5 m), so the band table and the formula never contradict each other. If a set sits at the top edge of a band, the band value is the safe reading.\n\n### DG Stack Height Table by kVA Rating\n\nMost people looking up the norm have one specific generator in mind. The table below gives the clearance above the building (0.2 × √kVA) and the resulting minimum stack height above ground for four common building heights. Values are rounded up to the next 0.1 m, because a stack is never built shorter than the statutory minimum. A building height of 3 m corresponds to a typical single-storey generator room.\n\n| DG rating | 0.2 × √kVA | h = 3 m | h = 6 m | h = 10 m | h = 15 m |\n|---|---|---|---|---|---|\n| 15 kVA | 0.77 m | 3.8 m | 6.8 m | 10.8 m | 15.8 m |\n| 25 kVA | 1.00 m | 4.0 m | 7.0 m | 11.0 m | 16.0 m |\n| 62.5 kVA | 1.58 m | 4.6 m | 7.6 m | 11.6 m | 16.6 m |\n| 82.5 kVA | 1.82 m | 4.9 m | 7.9 m | 11.9 m | 16.9 m |\n| 100 kVA | 2.00 m | 5.0 m | 8.0 m | 12.0 m | 17.0 m |\n| 125 kVA | 2.24 m | 5.3 m | 8.3 m | 12.3 m | 17.3 m |\n| 160 kVA | 2.53 m | 5.6 m | 8.6 m | 12.6 m | 17.6 m |\n| 200 kVA | 2.83 m | 5.9 m | 8.9 m | 12.9 m | 17.9 m |\n| 250 kVA | 3.16 m | 6.2 m | 9.2 m | 13.2 m | 18.2 m |\n| 320 kVA | 3.58 m | 6.6 m | 9.6 m | 13.6 m | 18.6 m |\n| 380 kVA | 3.90 m | 6.9 m | 9.9 m | 13.9 m | 18.9 m |\n| 500 kVA | 4.47 m | 7.5 m | 10.5 m | 14.5 m | 19.5 m |\n| 625 kVA | 5.00 m | 8.0 m | 11.0 m | 15.0 m | 20.0 m |\n| 750 kVA | 5.48 m | 8.5 m | 11.5 m | 15.5 m | 20.5 m |\n| 1,010 kVA | 6.36 m | 9.4 m | 12.4 m | 16.4 m | 21.4 m |\n| 1,250 kVA | 7.07 m | 10.1 m | 13.1 m | 17.1 m | 22.1 m |\n| 1,500 kVA | 7.75 m | 10.8 m | 13.8 m | 17.8 m | 22.8 m |\n| 2,000 kVA | 8.94 m | 12.0 m | 15.0 m | 19.0 m | 24.0 m |\n| 2,500 kVA | 10.00 m | 13.0 m | 16.0 m | 20.0 m | 25.0 m |\n\nFor any other rating or building height, use the calculator above.\n\n### How to Calculate DG Stack Height, Step by Step\n\n1. **Take the rated capacity in kVA.** It is on the alternator nameplate and in the purchase order. If you only have a kW figure, convert it at the rated power factor, which for most Indian gensets is 0.8: kVA = kW ÷ 0.8. A 400 kW set is therefore a 500 kVA set.\n2. **Fix the building height h.** This is the height, in metres above ground, of the building in which the set is installed. For a set on a roof, it is the height of that roof. For a set in a yard next to a building, it is the building the stack runs along, and in practice the tallest building immediately adjoining the set.\n3. **Work out the clearance.** Take the square root of the kVA rating and multiply by 0.2. For 500 kVA: √500 = 22.36, and 0.2 × 22.36 = 4.47 m.\n4. **Add the two and round up.** H = 10 + 4.47 = 14.47 m, so the stack must be at least 14.5 m above ground level.\n5. **Check the consent conditions.** Your State Pollution Control Board's consent order, or the conditions of a building or fire approval, may set a higher figure. The higher figure governs.\n6. **Record the calculation.** Keep a one-page note with the nameplate rating, the measured building height, the arithmetic and a photograph or drawing of the stack. Inspectors and consent officers ask for it, and it settles questions quickly during renewals.\n\n### Rooftop, Basement and Containerised DG Sets\n\nThe formula is easy; the building height is where most disagreements come from.\n\n- **Rooftop sets.** The set is on the roof, so h is the height of that roof and the stack must rise a further 0.2 × √kVA above it. Watch for higher parapets, lift machine rooms or water tanks on the same roof; an exhaust that discharges below them is pulled down into their wake.\n- **Basement and stilt-level sets.** Common in malls, hospitals and commercial towers. The stack height is still measured from ground level, so the exhaust has to be ducted up through a shaft and discharged above the roof of the building. This is the most expensive case to correct later, so settle it at the design stage.\n- **Containerised or canopy sets in an open yard.** The canopy itself is not the building. SPCBs usually read h as the height of the building next to which the set operates, because that is the building whose occupants and air intakes the plume affects.\n- **Rental and temporary sets.** Sets brought in for construction or long events still discharge exhaust. Where a set will stay on site for months, expect the same requirement for an adequate stack.\n\n### Multiple DG Sets on One Site\n\nHospitals, data centres, malls, hotels and process plants often run banks of four to ten generators. Each set with its own stack is sized on its own capacity. Where several sets discharge through a common stack, the combined capacity is used, which gives a taller stack than any single set would need. A bank of large sets close together also behaves, for dispersion purposes, like one bigger source: the plumes merge and the ground-level concentrations add up. When the total installed capacity runs into several megawatts, or the site has hospitals, schools or housing nearby, a board may ask for a dispersion study rather than accept the formula alone. That study is usually a short AERMOD run with the sets as point sources and the surrounding buildings included for downwash.\n\n### Other DG Set Rules in India You Will Be Asked About\n\nStack height is one of several conditions that come with a generator. The others usually reviewed alongside it:\n\n- **Noise.** CPCB noise rules for DG sets up to 1,000 kVA require an acoustic enclosure or an acoustically treated room, with a limit of 75 dB(A) at 1 m from the enclosure surface. The enclosure deals with noise; it does not replace the stack, and the exhaust still has to be piped to the required height.\n- **Engine emission norms.** New gensets up to 800 kW sold in India must meet the CPCB IV+ emission norms, in force since July 2023. The manufacturer's type approval covers this; keep the certificate with the consent file.\n- **Consent.** In an industry, DG sets are listed in the unit's Consent to Establish and Consent to Operate. Commercial buildings and institutions with large installed capacity may need their own consent; the thresholds differ by state, so check with the regional office of your SPCB.\n- **Use restrictions.** In some regions, notably Delhi-NCR during the graded response season, routine DG operation is restricted. Stack height does not exempt a set from these orders.\n\n### When the Formula Is Not Enough\n\nThe DG formula is a minimum, not a guarantee. A dispersion study is worth doing, and is often requested, when:\n\n- the installed DG capacity is large or the sets run for long hours, not only as standby;\n- the stack is close to a taller building and its wake (downwash) will bring the plume to the ground;\n- there are sensitive receptors such as wards, classrooms or residential balconies within a few hundred metres;\n- the generators are part of a project that needs Environmental Clearance, where the EIA has to show predicted ground-level concentrations against the NAAQS.\n\nWe carry out these studies with AERMOD and BPIP-PRIME. See our [AERMOD air dispersion modelling service](/services/aermod-air-dispersion-modelling/), or run the model yourself with our [AERMOD software (free demo)](/services/aermod-software/).\n\n### Boiler Stack Height by Steam Capacity\n\nFor small and medium boilers, CPCB sets minimum stack heights by steam generation capacity, alongside the SO2 emission formula:\n\n| Boiler steam generation | Minimum stack height |\n|---|---|\n| Less than 2 tonnes/hour | 9 m, or 2.5 times the height of neighbouring buildings within 15 m — whichever is more |\n| 2 to 5 tonnes/hour | 12 m |\n| 5 to 10 tonnes/hour | 15 m |\n| 10 to 15 tonnes/hour | 18 m |\n| 15 to 20 tonnes/hour | 21 m |\n| 20 to 25 tonnes/hour | 24 m |\n| 25 to 30 tonnes/hour | 27 m |\n| More than 30 tonnes/hour | 30 m, or H = 14 Q^0.3 — whichever is more |\n\n### The SO2 and Particulate Formulae\n\nFor larger sources the height is calculated from the emission rate:\n\n- **SO2-based:** H = 14 × Q^0.3, where Q is the SO2 emission rate in kg/hr\n- **Particulate-based:** H = 74 × Q^0.27, where Q is the particulate emission rate in tonnes/hr\n\nThe design height is the highest of the values these give, and SPCBs generally do not accept less than 30 m for sources where the formula applies. Example: a boiler emitting 50 kg/hr of SO2 gives H = 14 × 50^0.3 = 14 × 3.23 ≈ **45 m**.\n\n## How Is Stack Height Actually Determined? Step by Step\n\nDetermining a compliant stack height is a structured engineering exercise, not a single formula plugged once.\n\n1. **Characterise the emission source.** Establish emission rates, exit gas temperature, exit velocity, stack diameter, and pollutant species from mass balance or emission factors.\n2. **Apply the CPCB minimum.** Compute the prescriptive minimum height using the applicable formula or capacity-based norm to fix the regulatory floor.\n3. **Collect site and meteorological data.** Gather at least one year of representative meteorological data, terrain elevation, and land-use classification around the site.\n4. **Map nearby structures.** Identify buildings and obstacles that could cause plume downwash, since these directly influence effective height.\n5. **Run air dispersion modelling.** Use a regulatory model to predict ground-level concentrations for the proposed height under varied weather conditions.\n6. **Compare against NAAQS.** Check predicted GLCs, including cumulative background, against ambient standards for each pollutant.\n7. **Iterate and finalise.** If concentrations exceed limits, increase height or adjust exit parameters, then re-model until the design is both compliant and efficient.\n\nThis iterative loop is where dispersion modelling earns its place. The CPCB formula gives a starting point; the model proves the design works for the actual site.\n\n## How Does Dispersion Modelling Fit Into Stack Height Calculation?\n\nAir dispersion modelling simulates how a plume travels, rises, and dilutes under real atmospheric conditions. It converts an emission rate and stack geometry into predicted pollutant concentrations at hundreds of ground receptors around the plant.\n\nPlume behaviour depends on more than height alone. Buoyancy from hot gases and momentum from exit velocity create additional plume rise, so the effective height of release is often greater than the physical stack height. Modelling captures these effects along with wind speed, atmospheric stability, mixing height, and terrain.\n\nModelling is essential because:\n\n- It accounts for building downwash that a simple formula ignores.\n- It handles complex and elevated terrain common across Indian industrial belts.\n- It predicts worst-case short-term and annual average concentrations.\n- It supports EIA reports, Environmental Clearance, and consent submissions with defensible data.\n\nRegulators increasingly expect model-backed justification for stack height in EIA and consent documents, especially for large or sensitive projects.\n\n## Which Models and Inputs Are Used?\n\nIndian consultants rely on internationally validated, regulatory-grade dispersion models. The choice depends on distance scale, terrain, and pollutant type.\n\n| Tool | Purpose in stack design |\n|---|---|\n| AERMOD | Steady-state Gaussian model for near-field ground-level concentrations |\n| AERMET | Meteorological pre-processor preparing weather data for AERMOD |\n| AERMAP | Terrain pre-processor converting elevation data into model inputs |\n| BPIP-PRIME | Building downwash analysis for stacks near structures |\n| CALPUFF | Long-range and complex-terrain puff modelling over larger domains |\n| GIS | Spatial mapping of receptors, terrain, land use, and impact contours |\n\nKey inputs include emission rate per pollutant, stack diameter, exit temperature and velocity, one year of hourly meteorological data, terrain elevation, land-use roughness, and the locations of sensitive receptors. The quality of these inputs directly determines how reliable the recommended height will be.\n\n## When Is a Detailed Stack Height Study Required?\n\nNot every source needs full modelling, but many do under Indian regulation and good practice.\n\nA detailed, model-backed study is typically required when:\n\n- A project seeks Environmental Clearance under the EIA Notification 2006.\n- The industry falls in a heavily polluting Red category with significant emission loads.\n- The site sits in complex terrain, a valley, or a critically polluted area.\n- Tall buildings or existing stacks nearby raise downwash concerns.\n- The SPCB or CPCB specifically asks for dispersion justification during consent.\n\nFor small boilers and DG sets, the prescriptive CPCB minimum often suffices. For thermal plants, cement, steel, refineries, and chemical units, dispersion modelling is effectively standard.\n\n## How Much Does Stack Height Depend on Emission Rate?\n\nThe relationship is direct but non-linear. Because the SO2 formula raises emission rate to the power 0.3, height grows slowly as emissions rise, but it grows steadily.\n\n| SO2 emission rate Q (kg per hour) | Approximate height H = 14 Q to the power 0.3 (metres) |\n|---|---|\n| 10 | Around 28 |\n| 50 | Around 44 |\n| 100 | Around 56 |\n| 500 | Around 90 |\n| 1000 | Around 111 |\n\nThese figures illustrate the trend and are not a substitute for a site-specific calculation. The final height must still clear building downwash and NAAQS checks, which can push the requirement above the formula value.\n\n## Who Is Responsible for Stack Height Compliance?\n\nResponsibility is shared across the project lifecycle. The industry or project proponent owns compliance and must install and maintain a stack of the approved height. Environmental and EIA consultants perform the calculation and modelling and prepare the technical justification.\n\nThe SPCB reviews and grants consent conditions, while CPCB sets the national framework and sector norms. MoEFCC and State Environment Impact Assessment Authorities issue Environmental Clearance where the EIA process applies. Coordinated, accurate documentation across these stakeholders is what keeps a project on schedule.\n\n## Common Mistakes in Stack Height Design\n\nEven experienced teams stumble on avoidable errors:\n\n- Using the CPCB minimum as the final height without a NAAQS check.\n- Ignoring building downwash from nearby structures and control rooms.\n- Relying on unrepresentative or short-duration meteorological data.\n- Overlooking cumulative impact from existing sources in the airshed.\n- Treating physical height and effective height as the same thing.\n- Failing to update the study when plant capacity or fuel changes.\n\nAvoiding these keeps the design defensible before regulators and robust in real operation.\n\n## How DSTechnoverse Helps\n\n**DSTechnoverse** is an Indian environmental and engineering consultancy specialising in **professional air dispersion modelling** and **CPCB-compliant stack height design** for industries across the country. Our work bridges regulatory formula requirements and rigorous scientific validation so clients receive a height that is both compliant and cost-efficient.\n\nOur process is thorough and transparent:\n\n- **Source and site assessment**, capturing emission rates, stack geometry, terrain, and nearby structures.\n- **Regulatory screening** against the applicable CPCB and SPCB norms to fix the minimum height.\n- **Meteorological and terrain processing** using **AERMET** and **AERMAP** with representative annual data.\n- **Downwash analysis** through **BPIP-PRIME** to account for building wake effects.\n- **Dispersion modelling** with **AERMOD** for near-field impact and **CALPUFF** for long-range and complex-terrain scenarios.\n- **GIS-based mapping** of ground-level concentration contours and sensitive receptors.\n- **Iterative optimisation** until predicted concentrations comfortably meet NAAQS.\n\nClients receive a detailed, submission-ready report covering the methodology, input data, model configuration, predicted ground-level concentrations for each pollutant, comparison against NAAQS, isopleth impact maps, and a clear recommended stack height with full technical justification. The deliverable is structured to support **Consent to Establish, Consent to Operate, EIA studies, and Environmental Clearance** applications.\n\nThere are two ways to work with us. For a consent application, an EIA chapter or a query from your SPCB, our team does the study and delivers the report. If you run studies regularly, our [AERMOD software](/services/aermod-software/) runs US EPA AERMOD in the browser with the met data and report prepared for you; the demo on your own site is free.\n\nIf you are planning a new facility, expanding capacity, or responding to a regulatory query on stack height, **contact DSTechnoverse** for an accurate, defensible, CPCB-aligned stack height and dispersion modelling study tailored to your site.\n\n## Frequently Asked Questions\n\n### What is the DG set stack height formula as per CPCB?\n\nH = h + 0.2 × √KVA, where h is the height of the building housing the generator in metres and KVA is the generator capacity. A 500 kVA set in a 10 m building needs a stack of at least 14.5 m.\n\n### What is the minimum boiler stack height as per CPCB?\n\nIt depends on steam generation: 9 m below 2 tonnes/hour, rising in steps to 30 m above 30 tonnes/hour, where the SO2 formula H = 14 Q^0.3 applies if it gives more.\n\n### What is the minimum stack height as per CPCB?\n\nCPCB does not set a single universal minimum. It prescribes sector-specific minimums, such as capacity-based heights for thermal power plants and the emission-rate formula H = 14 multiplied by Q to the power 0.3 for SO2 sources. Small sources may only need to clear the roof of the nearest building by a few metres.\n\n### Is dispersion modelling mandatory for stack height calculation?\n\nIt is effectively required for projects under the EIA Notification 2006, for large or heavily polluting industries, and wherever the SPCB or CPCB asks for scientific justification. For small boilers and DG sets, the prescriptive CPCB minimum height often suffices without full modelling.\n\n### What is the difference between physical height and effective height?\n\nPhysical height is the actual constructed height of the chimney. Effective height adds the plume rise caused by the buoyancy of hot gases and the momentum of exit velocity. Dispersion models compute effective height because it governs where the plume finally reaches ground level.\n\n### Which pollutants drive stack height design in India?\n\nSulphur dioxide, oxides of nitrogen, and particulate matter are the primary drivers. The governing pollutant is the one whose predicted ground-level concentration comes closest to its NAAQS limit, so the design height must satisfy the most demanding pollutant at the site.\n\n### Can a stack be too tall?\n\nYes. Excessive height increases capital cost, structural load, and wind stress without meaningful air quality benefit once NAAQS compliance is achieved. Good design finds the optimal height that satisfies regulatory and dispersion requirements while avoiding unnecessary expense.\n\n### How long does a stack height and dispersion study take?\n\nTimelines depend on data availability and project complexity. When representative meteorological and site data are ready, a focused study can be completed relatively quickly, while large EIA-linked projects with extensive receptor grids and cumulative impact analysis take longer.\n\n### What is the stack height of a 500 kVA DG set?\n\nThe stack must rise 0.2 × √500 = 4.47 m above the building. In a 10 m building that means a stack of at least 14.5 m above ground; in a single-storey 6 m generator room, at least 10.5 m.\n\n### What is the stack height for a 1000 kVA DG set?\n\nThe clearance is 0.2 × √1000 = 6.32 m above the building. For a 15 m building the minimum stack height is 21.4 m; for a 10 m building it is 16.4 m.\n\n### What is the minimum stack height for a small DG set up to 50 kVA?\n\nUnder the CPCB bands, a set up to 50 kVA needs a stack of at least the height of the building plus 1.5 m. Sets of 50 to 100 kVA need building height plus 2.0 m.\n\n### Is kVA or kW used in the DG stack height formula?\n\nkVA. If only the kW rating is known, divide it by the power factor, usually 0.8. A 400 kW set is a 500 kVA set for the formula.\n\n### Does a DG set with an acoustic enclosure still need a full-height stack?\n\nYes. The acoustic enclosure is a noise control; the stack controls where the exhaust is released. The exhaust from an enclosed set still has to be piped up to the height given by the formula.\n\n### What is the boiler chimney height as per the pollution control board?\n\nSmall boilers follow the steam-capacity table above: 9 m (or 2.5 times the height of neighbouring buildings within 15 m) below 2 tonnes/hour, rising in steps to 30 m above 30 tonnes/hour. Larger boilers use H = 14 Q^0.3 for SO2, and the higher result governs.\n","related":[{"slug":"aermod-vs-calpuff-or-air-dispersion-model-guide","title":"AERMOD vs CALPUFF for Indian EIA Projects: Which One Do You Need?"},{"slug":"air-quality-modelling-software-india","title":"Air Quality Modelling Software Used in India (AERMOD, CALPUFF & More)"},{"slug":"meteorological-data-for-air-modelling-india","title":"Meteorological Data for Air Dispersion Modelling in India"},{"slug":"naaqs-standards-india-explained","title":"NAAQS in India Explained: National Ambient Air Quality Standards"}]}