Climate Resilient Building Design

TIME SAVER STANDARDS

RATIOS
Site Selection
- Slope Suitability: ≤ 15% for construction; avoid > 25%.
- Soil Bearing Capacity (SBC): Minimum 100 kN/m² for stability.
- Orientation: Long axis aligned along E-W (hot climates) or N-S (temperate climates).
- Building Orientation: Long axis aligned 15° E of North for optimal solar performance in most Indian climates.
- Vegetation Coverage: Preserve at least 20-30% of the site area.
- Site Utilization: Hardscape to Softscape Ratio: 1:1.5 for balanced site drainage and microclimate enhancement.
- Green Space Allocation: Green cover: Minimum 25-30% of total site area for urban projects.
- Built-up Area to Plot Area: FAR (Floor Area Ratio): 1.5-3.0 for urban zones, 0.5-1.0 for rural zones.
- Trees placed 2-3x mature height away from buildings for optimal shading without blocking ventilation.
- Road to Plot Area Ratio: Roads = 10-15% of site area in residential layouts.
- Pedestrian Path Width: Minimum 1.5 m for walkways in residential areas; 3 m in commercial areas.
- Tree Spacing Ratio: Medium trees: Spacing 6-8 m; Large trees: 10-12 m for shade and biodiversity.
- Permeable to Impermeable Ratio: Minimum 1:1.5 for effective stormwater infiltration.
- Biophilia Ratio (Green Integration): 40-50% of visible outdoor spaces should integrate greenery.
- Acoustic Buffer Ratio: Planting width: 5-10 m for reducing noise by 6-10 dB.
- Car Parking Area Ratio: Urban areas: 1 car space per 40-50 m² of built-up area.
Concept Development
- Open Space to Built Area Ratio: 1.5:1 (urban), 2:1 (rural).
- Site Coverage: 30-50% for adequate natural ventilation.
- Courtyard Ratio: Courtyard area = 10-30% of the built footprint.
- Ground Coverage Ratio (GCR): Residential: 30-50% of total site area.
Massing Design
- Aspect Ratio (Length): 1.5:1 to 2:1 for passive ventilation and daylighting.
- Aspect Ratio for Hot-Dry Climates: 1:1.5 to 1:2 (minimizes heat gain).
- Aspect Ratio for Cold Climates: 1:1 (compact for heat retention).
- Surface Area to Volume Ratio (S/V): Lower for energy-efficient massing; aim for 0.3-0.6 m²/m³ in extreme climates.
- Building Height to Street Width Ratio: Minimum 1:1 to ensure natural light and ventilation.
Spatial Planning
- Setback Ratio: Minimum 1:1.5 (building height to setback width) for daylight.
- Open Space Ratio (OSR): 30-40% of total site area.
- Room Width to Height Ratio: 2:1 for optimal daylight.
Interior Layout
- Natural Ventilation Ratio: Openings = 10-15% of floor area.
- Daylit Area: Ensure 70-80% of occupied spaces receive daylight.
- Ceiling Height: Minimum 2.7 m for effective air circulation.
- Corridor Width to Occupant Ratio: Residential: 1.2 m/50 occupants; Commercial: 1.8 m/100 occupants.
- Core Area Efficiency Ratio: Core (stairs, lifts, services) ≤ 20% of built-up area.
- Elevator Capacity Ratio: 1 elevator per 50-75 occupants in commercial buildings.
Building Form
- Compactness Ratio: Higher compactness for cold climates (e.g., 1:1.5) and lower for hot-humid zones (e.g., 1:3).
- Glazing Ratio: 20-40% of façade area, depending on climate.
- Roof Slope: 15-25° in heavy rainfall areas.
Lighting & Daylighting
Daylight Penetration Depth: Rule of thumb: 2.5x window head height into the room.
Skylight to Roof Area Ratio: 5-10% of roof area for sufficient daylight without excessive heat gain.
Daylighting Ratio: Window area = 10-20% of floor area in moderate climates.
Glazing Orientation: North-facing glazing: 50-60% of window area & East/West-facing glazing: ≤ 20% of window area.
Light Shelf Projection Ratio: Horizontal light shelf depth: 1:1.5 of window height for optimal light diffusion.
Window Sill Height Ratio: Window sill height: 0.85-1.2 m from floor to ensure privacy and usable daylight.
Room Depth to Window Height Ratio: Daylit room depth: 2.5x window head height.
Natural Ventilation & Passive Cooling
- Cross-Ventilation Openings: At least 15-20% of the floor area.
- Distance Between Openings: Maximum 12 m for cross-ventilation efficiency.
- Tree Coverage: Plant trees on at least 30% of open space for shading and cooling.
- Air Changes per Hour (ACH): Natural ventilation: 5-8 ACH for residential, 8-12 ACH for industrial spaces.
- Openings to Floor Area Ratio: Cross-ventilation: Openings on opposite walls = 15-20% of floor area.
- Wind Corridor Ratio: Ideal corridor width to building height: 1:1 for effective wind flow.
- Ventilation Stack Height Ratio: Height difference between inlet and outlet: Minimum 1:10 of total building height for effective stack ventilation.
- Courtyard to Building Height Ratio: Courtyard width ≥ 2x average building height for effective ventilation and daylight.
- Ventilation Opening Placement Ratio: Openings should be placed at 10-15% of floor-to-ceiling height for stack effect.
- Air Movement Efficiency Ratio: Ceiling fans placed every 4.5-6 m radius for uniform air distribution.
Thermal Performance (Insulation and Comfort)
- Wall Insulation R-value: 2.0-3.5 m²·K/W, depending on climate zone.
- Roof Insulation R-value: 3.5-5.0 m²·K/W for hot climates.
- Window U-value: ≤ 3 W/m²·K in hot-dry regions
- Thermal Mass Ratio: Walls with high thermal mass: Thickness ≥ 230 mm for hot-dry climates.
- Wall Thickness Ratio:
Adobe/stone walls: 300-450 mm for hot-dry climates.
Brick cavity walls: 200-250 mm for composite climates.
- Roof Reflectance: Albedo ≥ 0.6 for cool roofs in hot climates.
- Thermal Bridging Ratio: ≤ 5% of envelope area in insulated buildings.
- Thermal Envelope Ratio: External envelope area to floor area ≤ 0.5 for compact building
- Heat Loss/Gain Ratio (Cold Climates):m Wall U-value ≤ 0.35 W/m²·K. and Roof U-value ≤ 0.20 W/m²·K.
- Thermal Comfort Range: Operative temperature maintained at 20-25°C.
- Roof Slope to Rainfall Ratio: Slope (°) = Rainfall in mm/year/50 for effective drainage.
Shading Design
- Horizontal Overhang Depth: At least 1.5x the window height for summer shading.
- Vertical Fin Ratio: Vertical fins spaced 2-4x fin width for effective shading on east/west facades.
- Overhang Projection Ratio (Horizontal Shading);
- Overhang depth = Height of Window / Sun Angle
- General rule: 1.5x window height for summer shading.
- Roof Area to Building Footprint Ratio: 1:1 to 1.2:1, accommodating overhangs for rain protection or shading.
Facade Optimization
- Window-to-Wall Ratio (WWR):
- 20-40% for hot-humid climates.
- 50-60% for cold climates with insulated glass.
- Reflectivity (Albedo): 0.3-0.5 for walls to reduce heat gain.
Material Selection
- Recycled Content Ratio: 20-30% of materials should be recycled or renewable.
- Locally Sourced Material Ratio: At least 70% to reduce embodied energy.
- Thermal Conductivity (k):
- Walls: ≤ 0.5 W/m·K
- Roofs: ≤ 0.3 W/m·K
Green Roofing
- Green Coverage Ratio: 40-60% of total roof area.
- Soil Depth: 100-150 mm for lightweight green roofs.
- Plant Density: Minimum 80-90% coverage for cooling efficiency.
- Green Roof Soil Weight: Dry weight: 80-120 kg/m² for lightweight systems.
- Plant Canopy Coverage Ratio: Minimum 50% of landscaped area covered with tree canopy.
Water Management
- Rooftop Collection Efficiency: ≥ 80% of annual rainfall.
- Storage Tank Volume: 15−20×Daily Water Demand (m³)15-20 \times \text{Daily Water Demand (m³)}15−20×Daily Water Demand (m³).
- Runoff Coefficient: 0.8 for concrete roofs, 0.5 for green roofs.
- Water Retention Area: 2-5% of site area allocated for rainwater detention ponds or infiltration.
- Groundwater Recharge Pits: 1 pit per 300-500 m² of paved area for effective recharge.
- Water Tank Capacity Ratio: Domestic: 135-150 liters/person/day.
- Greywater to Freshwater Ratio: Greywater reuse should cover 30-40% of total water demand.
- Pervious Paving Ratio: ≥ 40% of hardscape should use pervious materials for water recharge.
Stormwater Management
- Permeable Surface Ratio: At least 30% of total site area.
- Detention Pond Volume: 0.03 m³/m² of impervious area.
- Drainage Gradient: 1:200 for effective water flow.
Acoustic Comfort
- Noise Buffer Ratio: Vegetation buffer: 10-15 m wide greenbelt reduces noise by 5-10 dB.
- Wall Insulation Ratio for Soundproofing: Wall density: 250-300 kg/m² for sound transmission class (STC) ≥ 50.
Lighting and Energy Efficiency
Artificial Lighting Power Density (LPD):
- Residential: ≤ 6 W/m².
- Office Spaces: ≤ 10 W/m².
- Window to Ceiling Height Ratio: Glazed window height = 1/4 to 1/3 of ceiling height for balanced daylight.
- Photovoltaic Panel Area Ratio: 1 kW capacity = 10 m² of PV panels.
Waste Management
- Composting Area Ratio: Compost pits: 1 m² per 50 occupants in residential complexes.
- Waste Segregation Area: Allocate 1.5-2 m² per floor for bins in multi-storey buildings.
- Recycling Efficiency Ratio: Aim for recycling at least 50-60% of solid waste on-site.
FORMULAE
Site Selection
Max Allowable Slope
Formula :- (S)=tan ^−1 ( ΔHeight/ΔHorizontal Distance)
Example :- ΔH=3 m, ΔD=15 m S=tan⁡^-1(3/15)=11.3°
Groundwater Recharge Volume
V=A⋅P⋅Rˇc , where: A= Catchment Area (m²), P= Rainfall (mm), Rˇc= Runoff Coefficient.
Example: A=200 m²,P=800 mm,Rc=0.6: V= 200⋅0.8⋅0.6 =96m³
Concept Development
Open Space Ratio (OSR)
OSR=Open Area / Plot Area×100
Example: Open Area = 300 m², Plot Area = 1000 m²
Building Coverage Ratio (BCR)
BCR=Built-up Area / Plot Area×100
Massing Design
Surface Area to Volume Ratio (S/V)
Window-Wall Ratio (WSA/TSA)
Window-Floor Area Ratio (WSA/FSA)
Spatial Planning
Setback Formula
S = Building Height / 1.5
Room Proportions for Daylight:
Depth = 2.5xWindow Height
Interior Layout
Ventilation Openings
O = Floor Area (m²) / Ventilation Ratio
Example: Floor Area = 50 m², Ventilation Ratio = 20%:
O = 50/0.2 = 10m² of openings.
Building Form
Aspect Ratio:
AR=Length / Width
Lighting and Daylighting
Daylight Factor (DF)
DF=Window Area (m²) / Floor Area (m²) 0.2
Daylight Penetration Depth:
D=2.5 × H, where H is Window Head Height.
Passive Cooling & Natural Ventilation
Cross-Ventilation Efficiency:
V=Q/A , where: Q= Flow Rate (m³/s), A= Open Area (m²).
Thermal Performance
U-Value (Heat Transfer Coefficient)
U=1 / R , where R = Material Thickness / Thermal Conductivity
Shading Design
*Overhang Depth (Horizontal Shading):
D=H⋅ tan⁡(α), where H=Window Height, α=Sun Angle
Facade Optimization
WWR (Window to Wall Ratio):
WWR= Window Area / Wall Area ×100
Material Selection
Embodied Energy (EE):
EE=Mass (kg)×Energy Intensity (MJ/kg)
Green Roofing
Green Roof Load
L=Soil Depth (m)⋅Density (kg/m³)⋅Area (m²)
Water Management and Rainwater Harvesting
Rainwater Storage Volume:
V = A⋅P⋅R , where: R=Runoff Coefficient
Stormwater Management
Permeable Surface Area Requirement:
Aˇp=Total Site Area (m²) / Pervious Ratio
Waste Management
Compost Area Requirement
Aˇc=P⋅W , where P =Population, W = Waste Generated per Person (kg)
Acoustic Comfort
Sound Transmission Loss (STL)
STL=10⋅log⁡(Incident Energy / Transmitted Energy)
THUMB RULES
Site Selection
- Prefer flat or gently sloping sites; avoid slopes steeper than 15°.
- Ensure 50-70% permeability on the site for effective stormwater management.
- Orient the site to maximize north-south alignment for optimal solar gain and wind access.
- Maintain at least 30% green cover for large sites.
Concept Development
- Allocate 20-30% of the site for open spaces and landscaping.
- Use compact building forms with a Surface Area to Volume (S/V) ratio ≤ 0.5 in extreme climates.
- Zoning: Place high-activity spaces on the north side and passive zones on the south.
Massing Design
- Use an aspect ratio of 1.5:1 to 2:1 (length) for buildings in hot-dry climates.
- Reduce external surface area by avoiding unnecessary projections.
- Keep the building height below 1.5x street width to ensure adequate ventilation in urban areas.
Spatial Planning
- Maintain a clear hierarchy of public, semi-private, and private spaces.
- Allow 50% of each floor area to receive direct natural light.
- Ensure cross-ventilation by providing openings on at least two sides of rooms.
Interior Layout
- Rooms should have a depth ≤ 2.5 times the window head height to maximize daylight.
- Kitchens and wet areas should be on the east side to minimize heat gain and optimize ventilation.
- Bedrooms should be oriented toward the north or northeast for cooler comfort.
Building Form
- Use rectilinear or compact forms in extreme climates for thermal efficiency.
- For moderate climates, break massing into smaller interconnected volumes to optimize natural ventilation.
- Keep the roof-to-wall area ratio ≤ 0.8 to minimize heat gain in hot climates.
Lighting and Daylighting
- Use a Window-to-Wall Ratio (WWR) of 15-20% for hot-dry climates; 30-40% for temperate climates.
- Daylight penetration should be 2.5 times the window head height.
- Install skylights over spaces with depths greater than 6 m.
Passive Cooling & Natural Ventilation
- Design openings to occupy 15-20% of the floor area for effective cross-ventilation.
- Use courtyards (10-15% of built-up area) to act as heat sinks in hot climates.
- Provide ventilation openings at different heights for stack effect cooling.
Thermal Performance
- Use walls with U-values ≤ 0.35 W/m²·K and roofs with U-values ≤ 0.25 W/m²·K.
- Ensure a thermal lag of 8-12 hours for walls to counter peak heat.
- Adopt high-albedo materials for walls and roofs with a reflectivity of at least 0.6.
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Shading Design
- Horizontal overhang depth = 1.5x window height for south-facing windows.
- Use vertical fins or louvers for east and west-facing facades.
- Plant native trees at a distance of 2-3x their mature height for optimal shading.
Facade Optimization
- Reduce glazing area on east and west facades to ≤ 20% of wall area.
- Use double-glazed windows with a solar heat gain coefficient (SHGC) ≤ 0.4.
- Design facades with a light color palette to reflect heat and reduce cooling loads.
Material Selection
- Use locally sourced materials for at least 50% of total construction volume.
- Adopt materials with low embodied energy, such as fly ash bricks or rammed earth.
- Prefer finishes with high solar reflectance index (SRI) values, especially for roofs.
Green Roofing
- Soil depth: 100-150 mm for lightweight green roofs; 300-500 mm for intensive roofs.
- Design green roofs to cover at least 50% of roof area to reduce heat island effects.
- Incorporate native, drought-resistant plant species to minimize water usage.
Water Management and Rainwater Harvesting
- Harvest at least 60-70% of rooftop rainwater.
- Size storage tanks at 30-50 liters/m² of rooftop area.
- Allocate 5% of site area for recharge pits or detention ponds.
Stormwater Management
- Design permeable surfaces to cover at least 40% of paved areas.
- Use bioswales or trenches with 0.5-1% slopes for efficient drainage.
- Install retention ponds sized to store 20-30% of peak rainfall runoff.
Waste Management
- Allocate 1.5-2 m² per 100 occupants for waste segregation.
- Compost 50-60% of organic waste on-site using pits or mechanical composters.
- Ensure that construction waste is recycled or reused for at least 30% of total waste.
Acoustic Comfort
- Wall density should be ≥ 250 kg/m² to achieve sound insulation of 45-50 dB.
- Plant 10-15 m wide green buffers around noisy areas like roads or factories.
- Window-to-room surface ratio: ≤ 10% in noisy areas to minimize external noise intrusion.

ARCHIVE/Architectural Design/Building Planning Principles

LLM RAW
For each of the following point; Give me time saver thumb rules for the book Climate responsive and sustainable building design guidelines in India
Site Selection
Concept Development
Massing Design
Spatial Planning
Interior Layout
Building Form
Lighting and Daylighting
Passive Cooling & Natural Ventilation
Thermal Performance
Shading Design
Facade Optimization
Material Selection
Green Roofing
Water Management and Rainwater Harvesting
Stormwater Management
Waste Management
Acoustic Comfort