Sustainable Building Design and Renewable Applications

THE HONG KONG POLYTECHNIC UNIVERSITY 香港理工大學 Sustainable Building Design and Renewable Applications Dr. Lu Lin, Vivien Associate Professor Department of Building Services Engineering The Hong Kong Polytechnic University

Overview Introduction of building sustainable design Passive architectural design sensitivity analysis and optimization Green building nanomaterial development Building energy efficient systems (Fluid mechanics and heat/mass transfer) Renewable energy applications

Introduction of building sustainable design Passive architectural design sensitivity analysis and optimization Green building nanomaterial development Building energy efficient systems (Fluid mechanics and heat/mass transfer) Renewable energy applications

Building sustainable design background Energy use in buildings accounts for about 92.7% of all electricity consumption according to statistics published in 2013 People spend about 80% to 90% of the time on indoor activities

Building sustainable design technologies Passive Architectural Design Green Material Active Energy Efficient Systems Renewable Applications To keep indoor environment comfortable while achieve energy saving, passive or active building designs can be adopted: Passive design use ambient energy sources, including daylighting, natural ventilation, and solar radiation. Active design use or create purchased energy to keep the building comfortable. Hybrid design use both energy sources

Building sustainable strategies from early design stages Degree of Effort Building Sustainability Program Predesign Schematic Design Design Development Construction Document Construction Management Post - Construction Research Target Design to Construction Time Line Source: The ASHRAE GreenGuide

Passive architectural design in green building rating tools

Building Passive architectural design classification Building Layout: Building orientation and external obstructions Building Geometry: structural ratios and external shadings Thermal Physics: Envelope physical properties Infiltration: Air-tightness criteria

Statistical analysis of Passive architectural design strategies Construct building model and determine inputs Generate Monte Carlo matrix Determine sampling size Sensitivity analysis Statistical modelling Multiple linear regression Rank transformed regression Multiple linear regression Non-parametric regression Determine sensitivity coefficient Determine surrogate model Bootstrapping Cross-validation

Passive architectural design case study buildings Over 90% of the population in HK lives in high-rise domestic buildings of 10 to 40 floors Public Rental Housing (PRH) provided accommodations for over 30% the local residents

Importance of different building design factors on building energy consumption To determine the ranking of various design strategies Infiltration Air Mass Flowrate Overhang Projection Ratio WGR 5 4 2 Window U value Window SHGC 1 To estimate the uncertainty of annual energy consumption External Wall Specific Heat External Wall Thermal Resistance External Obstruction Angle 3 Building Orientation -1.000 -.500.000.500 1.000 SRRC

Multi-objective building optimization Energy Consumption (kwh/m 2 ) 90 80 70 60 50 40 30 20 10 0 Trade-offs Optimized Baseline 77.8% 77.8% 41.6% Lighting Energy Cooling Energy Total Energy Acoustics Security Lighting Quality Ventilation IEQ Amenities Hygiene Thermal Comfort IAQ Energy performance including cooling and lighting Indoor environmental quality including thermal comfort, lighting quality and ventilation. Non Sorting Genetic Algorithm II (NSGA-II) adopted to obtain Pareto frontier

Nano-paints for window heat insulation Buildings emitted 8.3 Gt carbon dioxide each year accounting for more than 30% of the greenhouse gas emissions in many developed countries. 2015/16 HKSAR Government ITF (UICP): Development of Novel High Dispersed Transparent Heat Insulation Paints for Glass (UIM/265) Windows or curtain walls, taken as the daylighting structure of a building, is still suffering from the balance of thermal insulation and visible transparency.

Our ongoing ITF project Novel High Dispersed Transparent Heat Insulation Paints for Glass Problems for traditional coating 1. High cost (Foreign monopoly) 2. Bad transparence (Poor dispersion) 3. Solvent based coating (Environmental problems) Project Objective 1. Independent research to reduce the cost (Break up foreign monopoly) 2. Good transparence (Stable colloid) 3. Water based coating (Environmentally friendly ) Acrylic resin

Thermal insulation coating Size of ATO: 5nm Size of ATO: 50nm Size of FTO: 20nm secondary particle size (in water): <200nm

Thermal insulation coating Graphene Precursor of ATO Hydrothermal reactor Ball mill ATO-Graphene 1. Good dispersion, no sediment 2. Secondary particle size (in water): <150nm 3. Primary particle size: <30nm

Thermal insulation coating Number of samples Vis-Light Transmission IR-Light Transmission UV-Light Transmission 1 73 28 13 2 85 24 8 3 70 30 14 4 83 27 11 6 75 25 9 7 87 22 7 9 82 22 12 Insulation Performance of the Coating: Vis-Light Transmission: >75% IR-Light Transmission: <30% UV-Light Transmission:<15%

Self-cleaning coatings Super-hydrophobic, θ(lotus leaf)>150 Super-hydrophobic self-cleaning glass Super-hydrophilic,θ(clean glass)<10 Super-hydrophilic self-cleaning glass

Low-cost self-cleaning nano-coating for curtain walls Conventional self-cleaning glass curtain wall involves chemical vapour deposition and sputtering technologies. A comparison between PV modules with and without self-cleaning coatings after one month s outdoor exposure.

Building-integrated solar PV systems Natural ventilated PV façade (experimental and numerical) T / Y 0 55 50 PV facade Conventional facade T x 0 TEMPERATURE ( o C) 45 40 35 30 Interior surface temp. of PV facade 25 20 15:59 20:59 1:59 6:59 11:59 16:59 21:59 2:59 7:59 12:59 TIME T / Y 0 200 closed cavity Heat flux(w/m 2 ) 150 100 50 0 Optimum air thickness in the range of 60-80mm for energy savings in HK =7 o C 12 o C 10 20 30 40 50 60 70 80 90 100 Air gap thickness (mm) Y,V T x 0 U, V, T X,U open cavity

Solar cell development and installation orientation optimization Optimal installation orientation of PV modules Development of solar cells and PV product, etc. 1500 Direct-Integrated PV Roof Claddings Yeraly Solar Radiation (kwh/y) 1300 1100 900 0-90 -45 45 700 90 500 0 10 20 30 40 50 60 70 80 90 Tilted Angle (degree) Dye-sensitized solar cells based on graphite fibers

Ventilated BIPV and new modules The overall energy performance of BIPV facade: real-time power generation performance thermal performance natural lighting performance

Rooftop solar photovoltaic applications in Hong Kong The potential PV electricity output is about 4674GWh, accounts for 10.7% of the total electricity use in 2014. Evaluating the PV-suitable roof-top areas by using remote sensing imagery; Rooftop extraction from remote sensing imagery is employed to estimate the utilization rate of urban roofs

Thermal performance of ground-source heat pumps Simulation and experiments of vertical and inclined boreholes

Development of heat exchanger foundation pile considering its thermo-mechanical behaviour We firstly proposed a reliable analytical solution both considering the finiteness of heat source and difference of thermal property in the molding process. Thermal vertical stresses distributions Cracks may occur for long-term operation, and we need to explore its long-term operation with fatigue test to know its ultimate bearing capacity in the whole life-cycle.

Solar-assisted ground source heat pump system 1 Solar direct heating 2 Solar heat pump heating 3 4 Ground-source heating Solar coupled ground source heating 5 Solar energy storage and recharging 6 DHW production

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