Selection of Water-Efficient Fixtures and Water Use Efficiency Management
The application of water-efficient fixtures is the first gateway to water conservation in hotels. Selection criteria: (1) Water closets: adopt Grade 1 water efficiency (average flush volume not exceeding 4.0L; dual-flush with full flush not exceeding 5.0L and reduced flush not exceeding 3.5L); siphon-jet or vortex siphon flushing methods are recommended; (2) Faucets: adopt sensor-operated or aerated faucets with flow rate not exceeding 0.10L/s (washbasin) and 0.15L/s (kitchen); (3) Showerheads: adopt air-injection technology with flow rate not exceeding 0.09L/s (recommended for five-star hotels) or 0.12L/s (standard requirement); (4) Urinals: adopt sensor-operated flush valves with flush volume not exceeding 1.5L per flush. The water efficiency labeling system is fully implemented nationwide; hotels should verify the water efficiency grade of products during procurement. Water use efficiency management also includes setting reasonable water supply pressure (terminal pressure 0.15-0.25MPa), as over-pressure outflow causes substantial water waste.
Application of Renewable Energy and Heat Pump Technology
The application of renewable energy in hotel hot water systems is a core measure for energy conservation and carbon reduction. Mainstream technical solutions: (1) Air-source heat pump hot water system: utilizes the reverse Carnot cycle principle to absorb low-grade heat from ambient air, with COP of 3.0-5.0. Suitable for the Yangtze River basin and regions to the south; good energy efficiency performance when ambient temperature is above -5 degrees; (2) Solar hot water system: adopts flat-plate or evacuated-tube collectors, with solar fraction of 50%-70%; auxiliary heat source (electric heating or gas boiler) is required for cloudy and rainy days; (3) Ground-source heat pump system: utilizes the underground constant-temperature layer (10-20 degrees) as heat source, with COP up to 4.0-6.0; higher initial investment but lowest operating cost. Recommended solution: a combination of solar energy + air-source heat pump + gas boiler (standby) to achieve energy-optimized year-round hot water supply. According to the mandatory requirements of GB 55015-2021, new hotels must be equipped with solar hot water systems with a solar fraction of no less than 50%.
Reclaimed Water Reuse and Rainwater Harvesting Systems
Reclaimed water reuse and rainwater harvesting are important measures for achieving water resource recycling in hotels. Design requirements: (1) Reclaimed water source: hotel wastewater (shower, washbasin, and laundry drainage) is prioritized for collection due to relatively good water quality and low treatment cost. MBR membrane bioreactor is recommended for the treatment process (stable effluent quality, SS and turbidity approaching zero); (2) Reclaimed water uses: landscape irrigation, landscape water body replenishment, road washing, underground garage washing, toilet flushing, etc. Reclaimed water pipes must be marked with dedicated identification (light green or light blue) and are strictly prohibited from connection with domestic drinking water pipes; (3) Rainwater harvesting: roof rainwater is collected and used after initial runoff diversion (2-3mm initial rainfall diversion) + filtration + disinfection. The rainwater storage tank volume is calculated based on the catchment area and local rainfall. The investment payback period of reclaimed water reuse systems is typically 5-8 years, with significant economic and environmental benefits in water-scarce regions.
Pipe Insulation Energy Conservation and Waste Heat Recovery
Pipe insulation is a fundamental energy conservation measure for hot water systems. According to Article 6.4.1 of GB 50015-2019, hot water supply and return pipes, heat medium water pipes, steam pipes, etc. shall all be insulated, and the insulation layer thickness shall be determined by heat loss calculation. Recommended insulation solutions: (1) Hot water risers: rubber-plastic sponge insulation, thickness 50mm (thermal conductivity not exceeding 0.038W/m·K), with aluminum foil or PAP protective layer as outer jacket; (2) Hot water branch pipes: rubber-plastic sponge insulation, thickness 30mm, with PVC jacket; (3) Pipes in pipe shafts: insulation layer thickness not less than 40mm, with fire-stop sealing at floor penetrations. Regarding waste heat recovery: (4) Air conditioning condensing heat recovery: heat pumps are used to convert air conditioning condensing heat into hot water (55-60 degrees), meeting part of the hot water demand; (5) Boiler flue gas waste heat recovery: flue gas condensing heat exchangers are installed to recover flue gas waste heat for preheating feedwater (efficiency improvement of 8%-12%); (6) Wastewater waste heat recovery: heat pumps are used to recover heat from laundry and shower drainage to preheat feedwater.