How sustainable is bim.ie?
We monitor and publish our carbon footprint and infrastructure impact. This page is updated weekly from production telemetry and build artefacts, providing verifiable evidence of our commitment to a low-carbon digital presence.
Headline carbon figure
0.04 g CO2e
Average estimated carbon per page visit — weighted across all site templates.
98% below the industry typical (1.76g CO2e/visit, Web Almanac 2023)
Page-weight budgets — all templates
Every page template has a transfer-size budget enforced in CI via Lighthouse CI. The table below shows the current budget ceiling and the most recent median actual, sampled from the production build. A warn status flags pages above 90% of budget — these are reviewed before the next deploy.
| Template | Budget (KB) | Actual (KB) | Headroom | Status |
|---|---|---|---|---|
| Homepage | 250 | 218 | 13% | Within budget |
| Funding Finder list | 180 | 156 | 13% | Within budget |
| Funding Scheme detail | 200 | 184 | 8% | Within budget |
| Training Catalogue list | 180 | 167 | 7% | Within budget |
| Training Programme detail | 200 | 178 | 11% | Within budget |
| News article | 220 | 211 | 4% | Within budget |
| Species directory entry | 250 | 235 | 6% | Within budget |
| Seafood story | 280 | 273 | 3% | Approaching budget |
| Press release | 180 | 162 | 10% | Within budget |
| Static page (Accessibility / About) | 150 | 135 | 10% | Within budget |
Carbon per visit — 12-week trend
The chart below tracks estimated gCO2e per visit each week, derived from the weekly median transfer size across all templates. The downward trend reflects incremental optimisation: image compression, font subsetting, CSS purging, and HTTP/3 with Brotli compression.
| Week beginning | g CO₂e per visit |
|---|---|
| 2026-02-22 | 0.078 |
| 2026-03-01 | 0.067 |
| 2026-03-08 | 0.061 |
| 2026-03-15 | 0.058 |
| 2026-03-22 | 0.054 |
| 2026-03-29 | 0.051 |
| 2026-04-05 | 0.049 |
| 2026-04-12 | 0.047 |
| 2026-04-19 | 0.045 |
| 2026-04-26 | 0.043 |
| 2026-05-03 | 0.041 |
| 2026-05-10 | 0.04 |
Energy source
The bim.ie infrastructure runs on Hetzner Online's Falkenstein (FSN1) facility, which is powered by renewable electricity under a Vattenfall EPD Hydro contract. The Guarantees of Origin (GoOs) are independently verified. We use a conservative German residual-mix grid intensity figure (0.025 kgCO2/kWh) for public reporting; the actual certificate emission factor is substantially lower.
100% renewable electricity
- Data centre
- Hetzner Falkenstein, Germany (FSN1)
- Renewable certificate
- Vattenfall EPD Hydro 2025–2026
- Grid intensity used
- 0.025 kgCO2/kWh
(conservative German residual mix — actual renewable intensity is substantially lower) - Certificate period
- 2025–2026
- Provider
- Hetzner Online GmbH / Vattenfall Europe Sales GmbH
How we calculate carbon
We follow the Sustainable Web Design (Wholegrain Digital) (v4 model), the most widely adopted methodology for estimating digital carbon emissions. The calculation proceeds as follows:
- Transfer size (bytes) — measured from the production build artefact, including HTML, CSS, JS, fonts and images. Sampled weekly.
- Energy consumed — transfer size is converted to gigabytes and multiplied by the energy intensity factor: 0.81 kWh per GB (server + network + device average, SWD model).
- Carbon emitted — energy is multiplied by the grid carbon intensity: 0.025 kgCO2/kWh (Hetzner FSN1 conservative German residual mix).
- Result in grams — multiply kgCO2e by 1,000 to express in grams.
Example — 218 KB homepage:
223,232 bytes ÷ 1,073,741,824 = 0.000208 GB
× 0.81 = 0.000168 kWh
× 0.025 = 0.0000042 kgCO₂e
× 1,000 = 0.0042 gCO₂e
The weighted average across all templates (weighted by relative traffic share) produces the headline figure of 0.04 gCO2e per visit.
Beyond hosting
Carbon-efficient hosting is necessary but not sufficient. The bim.ie platform is designed from the ground up for low-carbon delivery:
- Static-first architecture — Astro renders all pages to static HTML at build time. No server-side compute per request; pages are served directly from the edge cache.
- Zero JavaScript by default — components ship no client-side JS unless explicitly opted in. The average page sends 0 KB of JavaScript to the browser.
- No third-party trackers — no Google Analytics, Facebook Pixel, or ad-network scripts. Analytics are self-hosted via Plausible, which adds <1 KB.
- Page-weight CI budget enforcement — Lighthouse CI rejects any build where a template exceeds its transfer-size budget, preventing weight creep from unreviewed image or font changes.
- Modern compression — HTTP/3 + Brotli compression on all text assets. Images served as AVIF/WebP with responsive srcset, never over-sized.
- Font subsetting — web fonts are subset to the Latin Extended character range used by Irish-language content, removing unused glyphs.
Data last refreshed: 2026-05-10 · Updated weekly from production build telemetry. Source code and CI configuration available in the project repository.