Building Carbon Emissions
Buildings generate carbon emissions through two distinct pathways: operational carbon (energy consumed during building use) and embodied carbon (emissions from materials, construction, and demolition). Operational carbon typically accounts for 70-80% of a building's lifecycle emissions, making energy efficiency the primary carbon reduction strategy for existing buildings.
Emission Scopes for Buildings (GHG Protocol)
| Scope | Source | Examples | Who Reports |
|---|---|---|---|
| Scope 1 — Direct | On-site combustion | Gas boilers, diesel generators, refrigerant leaks | Building owner/operator |
| Scope 2 — Indirect (Energy) | Purchased electricity, heating, cooling | Grid electricity for HVAC, lighting, equipment | Building owner/operator |
| Scope 3 — Value chain | Upstream/downstream | Tenant energy use, embodied carbon in materials, waste disposal, employee commuting | Increasingly required by frameworks |
Key Carbon Metrics
| Metric | Good Practice (Office) | Average | Poor |
|---|---|---|---|
| Carbon intensity (operational) | 30–60 kgCO₂e/m²/yr | 60–120 kgCO₂e/m²/yr | > 150 kgCO₂e/m²/yr |
| Scope 1 — generator diesel | Minimal (backup only) | 5-15% of total emissions | > 25% (excessive generator use) |
| Scope 2 — grid electricity | Reduced by efficiency + renewables | 70-85% of building emissions | 100% with no efficiency measures |
| Refrigerant GWP | R-32 (GWP: 675) or R-1234yf (GWP: 4) | R-410A (GWP: 2,088) | R-22 (GWP: 1,810, being phased out) |
| Renewable energy offset | ≥ 20% of electricity | 5-20% | 0% with no plan |
Calculating Building Carbon Emissions
The GHG Protocol provides the standard methodology:
- Collect activity data: electricity bills (kWh), fuel consumption (litres/m³), refrigerant purchases (kg)
- Apply emission factors:
- Grid electricity: country/grid-specific factor (Bangladesh: ~0.55 kgCO₂/kWh)
- Diesel generator: 2.68 kgCO₂/litre
- Natural gas: 2.0 kgCO₂/m³
- Refrigerant: mass leaked × GWP
- Sum by scope: Scope 1 + Scope 2 = total reported emissions. Include Scope 3 if required.
- Normalise: Divide total by GFA (m²) for carbon intensity metric.
Carbon Reduction Strategies
| Strategy | Carbon Reduction | Priority |
|---|---|---|
| Energy efficiency (HVAC, lighting, BMS optimization) | 20–40% of operational carbon | First — lowest cost, highest impact |
| LED lighting retrofit | 5–12% of total emissions | Quick win — 1-3 year payback |
| On-site solar PV | 5–15% of Scope 2 | Medium-term investment |
| Refrigerant transition (R-22→low-GWP) | Eliminates HFC fugitive emissions | At equipment replacement cycle |
| Green electricity procurement (RECs/PPAs) | Up to 100% of Scope 2 | Where available |
| Reduce diesel generator dependency | Reduces Scope 1 | Improve grid connection reliability |
Net-Zero Carbon Pathway
The World Green Building Council defines net-zero carbon buildings as: highly energy-efficient buildings with remaining energy from on-site or off-site renewable sources, with any remaining emissions offset.
The pathway: Measure → Reduce → Switch → Offset — in that order. Offsetting without first reducing is not credible.
Bangladesh Context
- Grid emission factor: ~0.55 kgCO₂/kWh (2023). Predominantly gas and coal. Higher than countries with more renewables.
- Generator dependence: Load-shedding means many Dhaka buildings run diesel generators for hours daily — a significant Scope 1 source.
- R-22 still in use: Many existing HVAC systems use R-22 (HCFC). Phase-out is underway per Montreal Protocol obligations, but replacement is slow.
- Carbon reporting: Not yet mandatory domestically, but MNC tenants require it for global corporate reporting.
- Solar potential: Good solar irradiance (4.5-5.0 kWh/m²/day) but limited rooftop adoption on commercial buildings.
References
Insights & Guidance
- Buildings emit carbon through Scope 1 (on-site: generators, gas, refrigerants), Scope 2 (purchased electricity), and Scope 3 (tenant use, embodied carbon).
- Good practice carbon intensity: 30-60 kgCO₂e/m²/yr for offices. Above 150 is poor.
- Bangladesh grid factor: ~0.55 kgCO₂/kWh — higher than global average due to gas/coal mix.
- Energy efficiency first, then renewables, then offsets — this order is non-negotiable for credible net-zero.
- R-22 phase-out is mandatory but slow in Bangladesh — plan for refrigerant transition at equipment replacement.
- Diesel generator dependence in Dhaka is a significant and often-overlooked Scope 1 emission source.
Carbon reporting is becoming mandatory in major markets (EU CSRD, UK SECR, SEC Climate Rule). MNC tenants operating in Bangladesh must report building emissions to headquarters. Buildings that cannot provide carbon data — or that have high carbon intensity — face tenant attrition, regulatory risk, and declining asset value. The transition to net-zero is not optional — it is a question of pace.
- Untracked emissions — no measurement means no management. Generator fuel and refrigerant leaks are often invisible.
- Greenwashing accusations — claiming carbon neutrality through offsets alone without efficiency improvements.
- Stranded assets — high-carbon buildings become unlettable as tenants adopt SBTi commitments.
- Refrigerant penalties — R-22 import restrictions drive up service costs; unplanned replacement is expensive.
- Reporting failures — inability to provide Scope 1/2 data when requested by corporate tenants.
- GHG inventory report (Scope 1 and 2 minimum)
- Electricity consumption records (12+ months)
- Generator fuel consumption records
- Refrigerant purchase and leak records
- Grid emission factor used for calculations
- Carbon reduction plan with targets
- Generator running hours — are generators running daily or only during outages?
- HVAC equipment nameplate — what refrigerant is used? R-22 or modern?
- Solar installations on roof?
- Energy dashboard or carbon tracking display?
- Old, inefficient lighting or equipment still in use?
- Has a carbon footprint assessment (GHG inventory) been conducted?
- What are the building's Scope 1 and Scope 2 emissions?
- How many hours per day do generators run?
- What refrigerants are in use? Is there a transition plan for R-22?
- Is there a carbon reduction target and pathway?
- Is renewable energy used or planned?
- GHG inventory — sustainability consultant with GHG Protocol expertise.
- SBTi target-setting — carbon strategy consultant.
- Refrigerant transition — HVAC engineer for low-GWP alternatives assessment.
- Carbon offset procurement — verified carbon offset provider.