Solar Heat Load and Daylight Factor

• Here are some study notes based on the provided text:

Solar Heat Load Indicator

• Measures the amount of solar radiation entering a building through transparent surfaces.
• Represents the energy contributing to the heating of the interior space.
• Crucial for assessing cooling needs and designing strategies to minimize overheating, especially in warmer climates.

Importance of Solar Heat Load and Thermal Comfort

• Most important for rooms with large glazed areas
• Most important for those with direct sun exposure (south or west-facing rooms).
• Important for offices and living spaces where thermal comfort impacts productivity.

Daylight Factor (DF)

• DF is the ratio of illuminance indoors to unobstructed illuminance outdoors under an overcast sky.
• It expresses the amount of daylight available indoors as a percentage of outdoor daylight.
• DF = (Eint / Eout) × 100 [%]
• Eint = Illuminance inside the room
• Eout = Illuminance outdoors under an overcast sky

Daylight Autonomy (DA)

• DA is the percentage of time a point receives sufficient daylight (≥300 lux) from daylight alone.
• DA = (No. of hours illuminance above target / Total no. of occupied hours) × 100 [%]

Spatial Daylight Autonomy (sDA)

• sDA is the percentage of floor area that meets a minimum daylight illuminance level (e.g., 300 lux) for a specified percentage of occupied hours (e.g., 50%).
• Indicates how well-daylit a space is overall.
• sDA = (Area meeting DA target / Total floor area) × 100 [%]

Visible Transmittance (VT)

• VT, also known as Visible Light Transmittance (VLT) or Tvis, measures how much visible light passes through a window's glazing system.
• It's expressed as a dimensionless value between 0 and 1 (or as a percentage).
• VT affects daylight entering the space and the need for artificial lighting.
• Range: VT values are typically between 0.3 and 0.8 (30% to 80%).
• Factors affecting VT: glass coatings, tints, thickness, and number of panes
• Importance: Higher VT allows more natural light, reducing artificial lighting needs and it affects indoor ambiance.
• Trade-offs: Higher VT may increase solar heat gain.

Solar Heat Gain Coefficient (SHGC)

• SHGC measures how much solar radiation (heat) passes through a window.
• Expressed as a dimensionless number between 0 and 1.
• Represents the fraction of total solar energy transmitted, including both directly transmitted and absorbed heat that is later re-radiated indoors.
• An SHGC of 0 means no solar heat is transmitted and 1 means all solar heat is transmitted.
• Factors affecting SHGC: type of glazing, coatings/tints, and window frame material/design
• Applications: Lower SHGC is preferred in hot climates to minimize cooling demands, higher SHGC is ideal in cold climates to capture passive solar heat.

Backward Ray Tracing

• A rendering technique used in lighting simulation software where rays are traced from the eye into the scene.
• When a ray hits a pixel, the algorithm traces the path of that light ray backward, accumulating light and color information until it reaches a light source.
• Efficient for calculating lighting effects.

Rooms Critical for Daylight

• Rooms with small window-to-floor area ratios, as these have limited natural light access: bathrooms, storage rooms, or small offices.
• Rooms shaded by surroundings: lower floors surrounded by taller structures, basements, or inner-city apartments.
• Rooms with asymmetrical window placement: narrow corridors or deep-plan rooms which lead to areas far from the windows being poorly lit
• Permanently occupied rooms: living rooms, bedrooms, offices, and classrooms.

Measures to Improve Daylight Levels (Without Changing Room Geometry)

• Strategic use of reflective surfaces: light shelves, reflective ceilings, and light-colored walls to redirect sunlight deeper into a space. Light shelves can reflect sunlight up to 2.5 times their height into a room
• High-performance glazing: low-E coatings, multiple panes, and gas fills to optimize daylight transmission while minimizing unwanted heat gain and glare.
• Mirrors and glass elements: mirrors opposite windows and glass furniture/doors/partitions to scatter light and carry it further.
• Smart window treatments: sheer curtains, motorized blinds, coatings that increase visible light transmittance or top-down/bottom-up shades.

Conflicting Miljöbyggnad Indicators with Daylight Indicator

• Solar Heat Load: Maximizing daylight leads to large south-facing windows, which increases solar radiation and the risk of glare.
• Thermal Comfort (Summer): Larger window areas increase solar heat gain, leading to overheating and reduced thermal comfort.
• Energy Use: Increasing daylight levels can lead to higher heat loss in winter and increased cooling loads in summer.

Representative Concentration Pathways (RCPs)

• Climate scenarios projecting future greenhouse gas concentrations.
• Based on internally consistent assumptions about socioeconomic development, technological innovation, and policy choices.
• Serve as inputs for climate models to assess warming impacts by 2100.
• Each RCP is defined by its radiative forcing level (W/m²) by 2100.
  • RCP8.5: 8.5 W/m² (high emissions, no mitigation)
  • RCP6.0: 6.0 W/m² (moderate mitigation)
  • RCP4.5: 4.5 W/m² (intermediate mitigation)
  • RCP2.6: 2.6 W/m² (stringent mitigation)
  • Newer variants like RCP1.9 align with the Paris Agreement's 1.5°C goal.
• RCP2.6: global peak annual emissions are projected will be between 2010-2020 and will significantly decline
• RCP4.5: greenhouse gas emissions will peak around 2040
• RCP6.0: will peak around 2080
• RCP8.5 emissions will continue to rise throughout the 21st century

Climate Model Computations

• Computed: temperature, precipitation, sea level, wind patterns, and ocean currents.
• Not Computed: specific weather events, social/economic/political factors.

Climate Variables Impacting Building Performance

• Temperature: heating/cooling loads, thermal comfort, material performance.
• Solar Radiation: heating, daylighting, and photovoltaic energy generation.
• Precipitation/Snow: building envelope durability, stormwater management, flooding risks, roof loads, and insulation performance.
• Wind: ventilation rates, heat loss through infiltration, natural ventilation & structural loads.
• Humidity: thermal comfort, mold growth, can increase cooling loads or affect occupant comfort.
• Urban Heat Island (UHI) Effect: amplifies local temperatures, increasing cooling demands in dense urban areas.

Lighting Lecture Definitions

• Luminous flux is the total amount of visible light emitted by a light source per unit of time (lumen - lm).
• Luminous intensity is the luminous flux emitted in a particular direction per unit solid angle (candela - cd).
• Illuminance is the amount of luminous flux incident on a surface (lux - lx or lumen/m²).
• Luminance is the amount of light emitted, reflected, or transmitted by a surface, per unit area and solid angle (candela/m²).

Key Parameters Affecting Daylight in Buildings

• Orientation: Affects the amount and timing of direct sunlight exposure.
• Window Size and Placement: Larger windows and strategic placement increase daylight penetration.
• Glazing Properties (VT, SHGC): Visible transmittance (VT) affects light entering, while Solar Heat Gain Coefficient (SHGC) influences heat gain.
• External Obstructions: Nearby buildings, trees, block daylight
• Internal Reflectance: Light-colored surfaces reflect more light, improving daylight distribution.
• Sky Conditions: Overcast vs. sunny skies affect the amount and quality of available daylight.

Four Parameters Assessed by EN 17037

• Daylight Illuminance: Assess the amount of daylight in key areas.
• View Out: Considers quality and accessibility of outdoor from occupied spaces (distance, width, angle, quality, layers).
• Sunlight Exposure: Evaluates duration and intensity of sun exposure in habitable rooms.
• Glare Control: Addresses the potential for brightness and visual discomfort.

Color Rendering Index (CRI)

• Measures accurately a light source renders the colors of objects compared to a reference light source.
• Ranges from 0 to 100 (higher = better color rendering).

Acoustics Lecture

• The brain filters out constant sensory inputs and noise is defined as unwanted sound, both have a negative impact like hypertension
• Natural sounds are generally less disruptive.
• Repetitive, monotonous, or irregular noises are problematic.

Climatic Conditions and Reverberation Time

• Reverberation is how long sound remains within a room and it is impacted by materials
• Warmer, humid climates which require shorter reverberation
• Colder, drier climates may longer times add warmth and fullness

Sound Frequency

• The number of cycles of a sound wave per second (Hertz - Hz).
• Perceived as the pitch (higher is higher)

Intensity of Sound

• The amount of sound energy through a unit area per unit time.
• Proportional to the square of the sound pressure.

Sound Pressure Level (SPL)

• SPL is the local pressure deviation from ambient atmospheric pressure, caused by a wave.
• Is a logarithmic measure of the effective pressure of a sound relative to a reference value in decibels (dB)
• Formula: SPL = 10 log (p²/Pref²) (dB)
  • Pref = 20 µPa
• +1dB: Smallest audible change
• +3 dB: Double sound
• +6 dB: Double pressure
• +10 dB: Double strength

Reference Pressure for SPL Calculation

• 20 micropascals (20 µPa), the threshold of human hearing at 1 kHz.

SPL Level for Ear Pain

• May occur beyond 120-140 dB.

Sounds, Perception, and Impact

• Sounds below 0.5Hz can caue severe physical effects
• Sounds betwen 5 Hz and 20 Hz cound cause discomfort and anoyance

Hearing Damage from Noise Exposure

• <50% exposed to ≤80 dB for 45 years may experience hearing damage.

Factors impacting intensity loss when sound is transmitted

• Materials Mass
• Stiffness
• Frequency
• Insulation
• Thickness

Sound wave properties in a physical medium

• Transmission
  • frequency = Unchanged
  • Speed and Wavelength, and Sound Pressure Level = change
• Reflection
  • frequency and Wavelength = Unchanged
  • Sound Pressure Level = decrease
• Refraction
  • frequency =Unchanged
  • Speed and Wavelength, and Sound Pressure Level = change
• Diffraction
  • frequency and Wavelength =- Unchanged
  • Sound Pressure Level decreases
• ABSORPTION - converts to heat
  • Sound Pressure Level absorbed
• Diffusion
  • frequency and Wavelength = Unchanged
  • Sound Pressure Level focused

Diffraction Concept

• Bending of waves around obstacles or openings when their size is similar to the wavelength.

Materials for Noise Reduction

• Sound-absorbing materials: Soft, porous materials like fiberglass and carpets.
• Sound-blocking materials: Dense, non-porous materials like concrete, brick, and metal.
• Vibration-damping materials: Rubber and resilient mounts.

How Sound Diffusion Is Used:

• Scattering of sound in many directions via specially designed surfaces
• It reduces reflections and it creates a more uniform sound field

Methods of Measuring Sound Exposure (IEC 61672)

• Time-weighting sound level meters
• Integrated-averaging
• Integrated by frequency

Strategic Noise Maps

• Used to evaluate and manage noise in planning, compliance, and mitigation
• Include: Experimental, subjective, and computational maps
• The most prominent source of outdoor noise is road traffic

Why do office landscapes equipped with cubicles may generate larger acoustic discomfort than an entirely open office landscape?

• Because of the "cocktail party effect."
• Partitions can reflect sound, increasing the overall noise and reducing focus
• In open spaces sound disperses more freely