A mid-size hotel's daily electricity use splits roughly into lighting/plug loads, heating & cooling (HVAC) and hot water. Each retrofit slider cuts its own share by up to the range quoted in industry case studies: LED + occupancy sensing trims lighting 30–50%, insulation and heat-recovery ventilation trim HVAC up to 45%, and heat-pump or solar-thermal water heating cuts hot-water demand 40–60%. Rooftop solar and wind then generate power against that reduced demand; whatever generation doesn't cover load still has to come from the grid.
consumption = Σ (baseline_i · (1 − retrofit_i))
generation = solarKW·sunFactor·8h + windKW·5h
grid draw = max(0, consumption − generation)
CO₂ saved = (baseline − grid draw·gridFactor) vs all-grid baseline
- LED & occupancy sensors — cuts the lighting/plug-load share of the budget.
- Insulation & heat recovery — cuts the heating/cooling share, the largest single load.
- Heat-pump / solar hot water — cuts the hot-water share.
- Rooftop solar PV / wind — on-site generation that offsets grid draw; a cloudy day roughly halves solar output while wind is unaffected.
Real-world relevance: this is exactly the lever set a hotel operator pulls when chasing an eco-certification like Green Key or EarthCheck — cut demand first, then cover the remainder with on-site renewables, watching the grid-draw bar shrink toward zero.