Energy Simulation
Overview
This skill implements building energy simulation and analysis. Calculate thermal loads, evaluate building envelope performance, and optimize systems for energy efficiency and code compliance.
Capabilities:
- Heating/cooling load calculations
- Envelope thermal analysis
- HVAC system sizing
- Energy code compliance
- Renewable energy integration
- Life cycle cost analysis
Quick Start
from dataclasses import dataclass, field
from typing import List, Dict, Optional, Tuple
from enum import Enum
import numpy as np
class WallType(Enum):
CONCRETE = "concrete"
BRICK = "brick"
WOOD_FRAME = "wood_frame"
STEEL_FRAME = "steel_frame"
CURTAIN_WALL = "curtain_wall"
@dataclass
class BuildingEnvelope:
wall_area_m2: float
wall_u_value: float # W/m²K
roof_area_m2: float
roof_u_value: float
floor_area_m2: float
floor_u_value: float
window_area_m2: float
window_u_value: float
window_shgc: float # Solar Heat Gain Coefficient
@dataclass
class ClimateData:
location: str
heating_degree_days: float # HDD base 18°C
cooling_degree_days: float # CDD base 18°C
design_temp_winter: float
design_temp_summer: float
def calculate_heat_loss(envelope: BuildingEnvelope, climate: ClimateData,
indoor_temp: float = 21) -> float:
"""Calculate design heat loss (W)"""
delta_t = indoor_temp - climate.design_temp_winter
# Transmission losses
wall_loss = envelope.wall_area_m2 * envelope.wall_u_value * delta_t
roof_loss = envelope.roof_area_m2 * envelope.roof_u_value * delta_t
floor_loss = envelope.floor_area_m2 * envelope.floor_u_value * delta_t * 0.5 # Ground factor
window_loss = envelope.window_area_m2 * envelope.window_u_value * delta_t
total_loss = wall_loss + roof_loss + floor_loss + window_loss
# Add infiltration estimate (simplified)
volume = envelope.floor_area_m2 * 3 # Assume 3m height
infiltration = volume * 0.5 * 0.33 * delta_t # 0.5 ACH, 0.33 Wh/m³K
return total_loss + infiltration
# Example
envelope = BuildingEnvelope(
wall_area_m2=500, wall_u_value=0.35,
roof_area_m2=200, roof_u_value=0.25,
floor_area_m2=200, floor_u_value=0.30,
window_area_m2=100, window_u_value=1.4, window_shgc=0.4
)
climate = ClimateData(
location="Moscow",
heating_degree_days=5000,
cooling_degree_days=300,
design_temp_winter=-25,
design_temp_summer=30
)
heat_loss = calculate_heat_loss(envelope, climate)
print(f"Design heat loss: {heat_loss/1000:.1f} kW")Comprehensive Energy Analysis
Building Thermal Model
from dataclasses import dataclass, field
from typing import List, Dict, Optional, Tuple
from enum import Enum
import numpy as np
from datetime import datetime
@dataclass
class MaterialLayer:
name: str
thickness_m: float
conductivity: float # W/mK
density: float # kg/m³
specific_heat: float # J/kgK
@property
def resistance(self) -> float:
"""Thermal resistance R (m²K/W)"""
return self.thickness_m / self.conductivity if self.conductivity > 0 else 0
@dataclass
class WallAssembly:
name: str
layers: List[MaterialLayer]
inside_surface_resistance: float = 0.13 # m²K/W
outside_surface_resistance: float = 0.04
@property
def total_resistance(self) -> float:
return (self.inside_surface_resistance +
sum(layer.resistance for layer in self.layers) +
self.outside_surface_resistance)
@property
def u_value(self) -> float:
return 1 / self.total_resistance if self.total_resistance > 0 else 0
@dataclass
class Window:
name: str
u_value: float
shgc: float
visible_transmittance: float = 0.6
frame_fraction: float = 0.2
@dataclass
class Zone:
zone_id: str
name: str
floor_area_m2: float
volume_m3: float
occupancy: int
lighting_power_density: float # W/m²
equipment_power_density: float # W/m²
ventilation_rate: float # L/s per person
setpoint_heating: float = 21
setpoint_cooling: float = 24
@dataclass
class BuildingGeometry:
zones: List[Zone]
walls: List[Dict] # {zone, orientation, area, assembly}
windows: List[Dict] # {zone, orientation, area, window_type}
roofs: List[Dict] # {zone, area, assembly}
floors: List[Dict] # {zone, area, assembly, is_ground}
class ThermalCalculator:
"""Calculate building thermal loads"""
# Standard climate data (simplified)
CLIMATE_DB = {
'moscow': {
'hdd': 5000, 'cdd': 300,
'design_winter': -25, 'design_summer': 30,
'latitude': 55.75
},
'new_york': {
'hdd': 2500, 'cdd': 800,
'design_winter': -12, 'design_summer': 33,
'latitude': 40.71
},
'dubai': {
'hdd': 50, 'cdd': 3000,
'design_winter': 15, 'design_summer': 45,
'latitude': 25.20
}
}
def __init__(self, building: BuildingGeometry, location: str):
self.building = building
self.location = location.lower()
self.climate = self.CLIMATE_DB.get(self.location, self.CLIMATE_DB['moscow'])
def calculate_design_heating_load(self) -> Dict:
"""Calculate design heating load for each zone"""
delta_t = 21 - self.climate['design_winter']
results = {}
for zone in self.building.zones:
# Transmission losses
wall_loss = 0
window_loss = 0
roof_loss = 0
floor_loss = 0
for wall in self.building.walls:
if wall['zone'] == zone.zone_id:
u_value = wall['assembly'].u_value
wall_loss += wall['area'] * u_value * delta_t
for window in self.building.windows:
if window['zone'] == zone.zone_id:
window_loss += window['area'] * window['window_type'].u_value * delta_t
for roof in self.building.roofs:
if roof['zone'] == zone.zone_id:
u_value = roof['assembly'].u_value
roof_loss += roof['area'] * u_value * delta_t
for floor in self.building.floors:
if floor['zone'] == zone.zone_id:
u_value = floor['assembly'].u_value
factor = 0.5 if floor.get('is_ground', False) else 1.0
floor_loss += floor['area'] * u_value * delta_t * factor
# Infiltration
infiltration_loss = zone.volume_m3 * 0.5 * 0.33 * delta_t
# Ventilation (if mechanical)
ventilation_loss = zone.occupancy * zone.ventilation_rate * 1.2 * delta_t
total = wall_loss + window_loss + roof_loss + floor_loss + infiltration_loss + ventilation_loss
results[zone.zone_id] = {
'zone_name': zone.name,
'wall_loss_w': wall_loss,
'window_loss_w': window_loss,
'roof_loss_w': roof_loss,
'floor_loss_w': floor_loss,
'infiltration_w': infiltration_loss,
'ventilation_w': ventilation_loss,
'total_w': total,
'total_kw': total / 1000,
'w_per_m2': total / zone.floor_area_m2
}
return results
def calculate_design_cooling_load(self) -> Dict:
"""Calculate design cooling load for each zone"""
delta_t = self.climate['design_summer'] - 24
results = {}
for zone in self.building.zones:
# Transmission gains
transmission_gain = 0
for wall in self.building.walls:
if wall['zone'] == zone.zone_id:
u_value = wall['assembly'].u_value
# Apply sol-air temperature correction for orientation
sol_air_delta = delta_t + self._get_sol_air_correction(wall['orientation'])
transmission_gain += wall['area'] * u_value * sol_air_delta
# Window solar gains
solar_gain = 0
for window in self.building.windows:
if window['zone'] == zone.zone_id:
shgc = window['window_type'].shgc
irradiance = self._get_solar_irradiance(window['orientation'])
solar_gain += window['area'] * shgc * irradiance
# Window conduction
window_conduction = 0
for window in self.building.windows:
if window['zone'] == zone.zone_id:
window_conduction += window['area'] * window['window_type'].u_value * delta_t
# Internal gains
lighting_gain = zone.floor_area_m2 * zone.lighting_power_density
equipment_gain = zone.floor_area_m2 * zone.equipment_power_density
people_gain = zone.occupancy * 75 # W per person sensible
# Ventilation
ventilation_gain = zone.occupancy * zone.ventilation_rate * 1.2 * delta_t
total = (transmission_gain + solar_gain + window_conduction +
lighting_gain + equipment_gain + people_gain + ventilation_gain)
results[zone.zone_id] = {
'zone_name': zone.name,
'transmission_gain_w': transmission_gain,
'solar_gain_w': solar_gain,
'window_conduction_w': window_conduction,
'lighting_gain_w': lighting_gain,
'equipment_gain_w': equipment_gain,
'people_gain_w': people_gain,
'ventilation_gain_w': ventilation_gain,
'total_w': total,
'total_kw': total / 1000,
'w_per_m2': total / zone.floor_area_m2
}
return results
def _get_sol_air_correction(self, orientation: str) -> float:
"""Get sol-air temperature correction by orientation"""
corrections = {
'north': 0, 'south': 8, 'east': 4, 'west': 6,
'northeast': 2, 'northwest': 3, 'southeast': 6, 'southwest': 7
}
return corrections.get(orientation.lower(), 3)
def _get_solar_irradiance(self, orientation: str) -> float:
"""Get design solar irradiance W/m² by orientation"""
# Simplified peak values
irradiance = {
'north': 150, 'south': 450, 'east': 350, 'west': 350,
'northeast': 200, 'northwest': 200, 'southeast': 400, 'southwest': 400
}
return irradiance.get(orientation.lower(), 300)HVAC System Sizing
class HVACSizer:
"""Size HVAC systems based on loads"""
def __init__(self, calculator: ThermalCalculator):
self.calculator = calculator
def size_heating_system(self, safety_factor: float = 1.15) -> Dict:
"""Size heating system"""
heating_loads = self.calculator.calculate_design_heating_load()
total_load = sum(z['total_kw'] for z in heating_loads.values())
sized_capacity = total_load * safety_factor
# Recommend system type
if sized_capacity < 15:
system_type = "Split system heat pump"
elif sized_capacity < 50:
system_type = "Packaged rooftop unit"
elif sized_capacity < 200:
system_type = "Central boiler with radiators"
else:
system_type = "Central plant with multiple boilers"
return {
'total_load_kw': total_load,
'sized_capacity_kw': sized_capacity,
'safety_factor': safety_factor,
'recommended_system': system_type,
'zone_loads': heating_loads
}
def size_cooling_system(self, safety_factor: float = 1.1) -> Dict:
"""Size cooling system"""
cooling_loads = self.calculator.calculate_design_cooling_load()
total_load = sum(z['total_kw'] for z in cooling_loads.values())
sized_capacity = total_load * safety_factor
# Convert to tons
capacity_tons = sized_capacity / 3.517
# Recommend system type
if capacity_tons < 5:
system_type = "Split system DX"
elif capacity_tons < 20:
system_type = "VRF system"
elif capacity_tons < 100:
system_type = "Chilled water with AHUs"
else:
system_type = "Central chiller plant"
return {
'total_load_kw': total_load,
'total_load_tons': capacity_tons,
'sized_capacity_kw': sized_capacity,
'sized_capacity_tons': capacity_tons * safety_factor,
'safety_factor': safety_factor,
'recommended_system': system_type,
'zone_loads': cooling_loads
}
def estimate_annual_energy(self) -> Dict:
"""Estimate annual energy consumption"""
climate = self.calculator.climate
heating_loads = self.calculator.calculate_design_heating_load()
cooling_loads = self.calculator.calculate_design_cooling_load()
total_heating_load = sum(z['total_kw'] for z in heating_loads.values())
total_cooling_load = sum(z['total_kw'] for z in cooling_loads.values())
# Simplified degree-day calculation
# Heating energy = load * HDD * 24 / delta_t_design
delta_t_heating = 21 - climate['design_winter']
heating_kwh = total_heating_load * climate['hdd'] * 24 / delta_t_heating / 1000
delta_t_cooling = climate['design_summer'] - 24
cooling_kwh = total_cooling_load * climate['cdd'] * 24 / delta_t_cooling / 1000 if delta_t_cooling > 0 else 0
# Apply efficiency factors
heating_fuel_efficiency = 0.9 # Gas boiler
cooling_cop = 3.5 # Chiller COP
heating_consumption = heating_kwh / heating_fuel_efficiency
cooling_consumption = cooling_kwh / cooling_cop
return {
'heating_load_kw': total_heating_load,
'cooling_load_kw': total_cooling_load,
'annual_heating_kwh': heating_kwh,
'annual_cooling_kwh': cooling_kwh,
'heating_fuel_kwh': heating_consumption,
'cooling_electricity_kwh': cooling_consumption,
'total_hvac_energy_kwh': heating_consumption + cooling_consumption
}Energy Code Compliance
@dataclass
class EnergyCodeRequirements:
code_name: str
climate_zone: str
wall_u_max: float
roof_u_max: float
floor_u_max: float
window_u_max: float
window_shgc_max: float
lighting_lpd_max: float # W/m²
class ComplianceChecker:
"""Check energy code compliance"""
CODES = {
'ASHRAE_90.1_2019_4A': EnergyCodeRequirements(
code_name="ASHRAE 90.1-2019",
climate_zone="4A",
wall_u_max=0.45,
roof_u_max=0.27,
floor_u_max=0.32,
window_u_max=2.0,
window_shgc_max=0.40,
lighting_lpd_max=9.0
),
'IECC_2021_5A': EnergyCodeRequirements(
code_name="IECC 2021",
climate_zone="5A",
wall_u_max=0.35,
roof_u_max=0.20,
floor_u_max=0.30,
window_u_max=1.7,
window_shgc_max=0.40,
lighting_lpd_max=8.5
)
}
def __init__(self, code_key: str):
self.requirements = self.CODES.get(code_key)
if not self.requirements:
raise ValueError(f"Unknown code: {code_key}")
def check_envelope(self, building: BuildingGeometry) -> Dict:
"""Check envelope compliance"""
results = {
'code': self.requirements.code_name,
'climate_zone': self.requirements.climate_zone,
'compliant': True,
'issues': []
}
# Check walls
for wall in building.walls:
u_value = wall['assembly'].u_value
if u_value > self.requirements.wall_u_max:
results['compliant'] = False
results['issues'].append({
'element': f"Wall {wall['zone']} {wall['orientation']}",
'actual': u_value,
'required': self.requirements.wall_u_max,
'issue': 'Exceeds maximum U-value'
})
# Check windows
for window in building.windows:
u_value = window['window_type'].u_value
shgc = window['window_type'].shgc
if u_value > self.requirements.window_u_max:
results['compliant'] = False
results['issues'].append({
'element': f"Window {window['zone']} {window['orientation']}",
'actual': u_value,
'required': self.requirements.window_u_max,
'issue': 'Exceeds maximum U-value'
})
if shgc > self.requirements.window_shgc_max:
results['compliant'] = False
results['issues'].append({
'element': f"Window {window['zone']} {window['orientation']}",
'actual': shgc,
'required': self.requirements.window_shgc_max,
'issue': 'Exceeds maximum SHGC'
})
# Check roof
for roof in building.roofs:
u_value = roof['assembly'].u_value
if u_value > self.requirements.roof_u_max:
results['compliant'] = False
results['issues'].append({
'element': f"Roof {roof['zone']}",
'actual': u_value,
'required': self.requirements.roof_u_max,
'issue': 'Exceeds maximum U-value'
})
return results
def check_lighting(self, zones: List[Zone]) -> Dict:
"""Check lighting power density compliance"""
results = {
'compliant': True,
'issues': []
}
for zone in zones:
if zone.lighting_power_density > self.requirements.lighting_lpd_max:
results['compliant'] = False
results['issues'].append({
'zone': zone.name,
'actual_lpd': zone.lighting_power_density,
'required_max': self.requirements.lighting_lpd_max
})
return resultsQuick Reference
| Component | Good U-Value | Code Maximum |
|---|---|---|
| Wall | < 0.25 W/m²K | 0.35-0.45 |
| Roof | < 0.15 W/m²K | 0.20-0.27 |
| Floor | < 0.20 W/m²K | 0.25-0.32 |
| Window | < 1.2 W/m²K | 1.7-2.0 |
Resources
- ASHRAE 90.1: Energy standard for buildings
- IECC: International Energy Conservation Code
- EnergyPlus: DOE building simulation
- DDC Website: https://datadrivenconstruction.io
Next Steps
- See
co2-estimationfor carbon analysis - See
cost-predictionfor energy cost modeling - See
bim-validation-pipelinefor model integration