Green Building Systems: Features, Appraisal, and Ventilation

Chapter: Green Building Systems: Features, Appraisal, and Ventilation

Introduction

Green building systems represent a holistic approach to design, construction, and operation that minimizes environmental impact while maximizing occupant health and productivity. This chapter delves into the features of green building systems, methods for appraising their value, and the critical role of ventilation in achieving sustainability goals. We will explore relevant scientific theories, practical applications, and utilize mathematical formulas to quantify performance.

1. Features of Green Building Systems

Green building design encompasses several key elements, often referred to as the “Six Elements of Green Building”:

• 1.1 Site Selection and Development:

  • Minimizing site disruption: Reducing the impact on existing ecosystems through careful planning and construction practices.

  • Erosion and sedimentation control: Implementing measures to prevent soil erosion and water pollution during construction.

  • Stormwater management: Designing systems to capture and treat stormwater runoff, reducing the burden on municipal infrastructure and mitigating flooding. Examples include bioswales, permeable pavement, and rainwater harvesting systems.

  • Heat Island Effect Reduction: Using reflective roofing materials and planting vegetation to lower the surface temperature of the building and surrounding areas, mitigating the urban heat island effect.

• 1.2 Water Efficiency:

  • Water-efficient fixtures: Installing low-flow toilets, faucets, and showerheads to reduce water consumption.

  • Rainwater harvesting: Collecting rainwater for non-potable uses such as irrigation and toilet flushing.

  • Greywater recycling: Treating and reusing wastewater from showers, sinks, and laundry for irrigation or toilet flushing.

  • Water-efficient landscaping: Using native and drought-tolerant plants that require minimal irrigation.

• 1.3 Energy Efficiency:

  • High-performance building envelope: Designing the building shell to minimize heat loss in winter and heat gain in summer, reducing the need for heating and cooling.

  • High-efficiency HVAC systems: Utilizing heating, ventilation, and air conditioning (HVAC) systems with high energy efficiency ratings.

    • Heating systems may include: Warm or hot air, Hot water, Steam, Electric.
    • Air-conditioning and ventilation systems.

  • Renewable energy sources: Integrating solar photovoltaic (PV) systems, geothermal heating and cooling (ground source heat pumps), or wind turbines to generate on-site energy.

  • Optimized building orientation: Orienting the building to maximize daylighting and minimize solar heat gain.

  • Energy-efficient lighting: Using LED lighting and daylighting strategies to reduce energy consumption for lighting.

  • Smart building controls: Implementing automated systems to optimize energy use based on occupancy and environmental conditions.

  • On-site energy storage (batteries).

• 1.4 Materials Selection:

  • Recycled content: Using building materials with recycled content to reduce the demand for virgin resources.

  • Regional materials: Sourcing materials from local suppliers to reduce transportation emissions and support the local economy.

  • Rapidly renewable materials: Utilizing materials that can be replenished quickly, such as bamboo or cork.

  • Low-emitting materials: Selecting materials with low levels of volatile organic compounds (VOCs) to improve indoor air quality.

  • Life-cycle assessment: Evaluating the environmental impact of building materials throughout their entire life cycle.

• 1.5 Indoor Environmental Quality:

  • Ventilation: Providing adequate ventilation to remove pollutants and maintain healthy air quality. Using energy recovery ventilators (ERVs) or heat recovery ventilators (HRVs) to exchange air without losing energy.

  • Daylighting: Maximizing natural light to reduce the need for artificial lighting and improve occupant well-being.

  • Acoustic comfort: Designing spaces to minimize noise levels and create a comfortable acoustic environment.

  • Thermal comfort: Maintaining consistent temperature and humidity levels throughout the building.

  • Air filtration systems, such as high-efficiency particulate air (HEPA) filters, are effective in removing impurities from the air.

• 1.6 Operations and Maintenance:

  • Commissioning: Verifying that building systems are operating as designed.

  • Energy management: Monitoring and optimizing energy consumption over time.

  • Waste management: Implementing recycling and composting programs to reduce waste.

  • Green cleaning: Using environmentally friendly cleaning products and practices.

  • Occupant education: Educating occupants about the building’s green features and how to use them effectively.

  • Resilience features such as on-site bioswales and storm water retention and management (ponds, cisterns, permeable pavement).

2. Appraisal of Green Building Systems

Appraising green buildings requires considering the unique features and benefits that contribute to their value. Traditional appraisal methods may not fully capture the value of these features, so appraisers must use additional techniques and resources.

• 2.1 Challenges in Appraising Green Buildings:

  • Data scarcity: Limited availability of comparable sales data for green buildings.

  • Complexity of features: Difficulty in quantifying the value of intangible benefits such as improved indoor air quality and occupant well-being.

  • Market awareness: Lack of understanding and appreciation for green building features among buyers and sellers.

• 2.2 Appraisal Methods for Green Buildings:

  • Sales Comparison Approach:

    • Identify comparable sales of green buildings with similar features.

    • Adjust for differences in location, size, and other characteristics.

    • Quantify the value of green features based on market data and expert opinion.

    • Utilize addenda to appraisal reports that standardize the communication of green and/or high performing features of properties.

  • Cost Approach:

    • Estimate the cost of replacing the building with a similar green building.

    • Adjust for depreciation and obsolescence.

    • Consider the incremental cost of green features compared to conventional building practices.

  • Income Capitalization Approach:

    • Estimate the potential rental income and operating expenses of the green building.

    • Consider the potential for increased rental rates and reduced operating costs due to green features.

    • Apply an appropriate capitalization rate to determine the value of the building.

    • Calculate energy savings amounts to develop an income approach to support energy efficient value.

• 2.3 Resources for Appraising Green Buildings:

  • Green building rating systems: LEED, Energy Star, National Green Building Standard (NGBS), Home Energy Score (HES) provide a framework for evaluating and verifying green building performance.

  • Energy audits: Provide detailed information about a building’s energy consumption and potential for savings.

  • HERS Index: Measures the energy efficiency of a home, with lower scores indicating greater efficiency.

  • Building Performance Institute (BPI): Provides training and certification for building performance professionals.

  • Appraisal Institute: Offers resources and training for appraisers on green building valuation.

• 2.4 Key Factors in Green Building Appraisal:

  • Energy efficiency: Lower energy consumption and utility bills.

  • Water conservation: Reduced water consumption and utility bills.

  • Indoor air quality: Improved occupant health and productivity.

  • Durability and longevity: Reduced maintenance costs and extended building lifespan.

  • Market appeal: Increased demand and resale value.

3. Ventilation in Green Buildings

Ventilation is crucial for maintaining healthy indoor air quality and thermal comfort in green buildings. Proper ventilation removes pollutants, reduces moisture buildup, and provides fresh air for occupants.

• 3.1 Importance of Ventilation:

  • Removes pollutants: Ventilation removes pollutants such as VOCs, carbon dioxide, and allergens from the air.

  • Reduces moisture buildup: Ventilation prevents condensation and mold growth, which can damage building materials and harm occupant health.

  • Provides fresh air: Ventilation provides fresh air for occupants, improving their health and productivity.

  • Prevents the condensation of water, which collects in unventilated spaces and causes building materials to rot and decay. When condensation seeps into insulation, it reduces its R rating.

• 3.2 Types of Ventilation Systems:

  • Natural Ventilation:

    • Utilizes natural forces such as wind and buoyancy to drive airflow.
    • Operable windows, skylights, and ventilation stacks can be used to promote natural ventilation.
    • Design considerations: Building orientation, window placement, and shading devices.
    • Formula for calculating airflow through a window:
    • Q = A * v
      • Where:
        • Q = Airflow rate (m3/s)
        • A = Window area (m2)
        • v = Average wind speed (m/s)

  • Mechanical Ventilation:

    • Uses fans and ductwork to control airflow.
    • Exhaust fans, supply fans, and balanced ventilation systems can be used to provide mechanical ventilation.

  • Balanced Ventilation:

    • Supply and exhaust air at equal rates.
    • Energy recovery ventilators (ERVs) and heat recovery ventilators (HRVs) are balanced ventilation systems that recover energy from exhaust air.

• 3.3 Energy Recovery Ventilation (ERV) and Heat Recovery Ventilation (HRV):

  • HRV: Transfers heat between incoming and outgoing air streams. Suitable for climates with large temperature differences between indoors and outdoors.

  • ERV: Transfers both heat and moisture between incoming and outgoing air streams. Suitable for climates with high humidity levels.

  • ERV and HRV systems improve indoor air quality while reducing energy consumption for heating and cooling.

  • Formula for calculating energy savings from HRV/ERV:

    • Esavings = Q * ρ * Cp * (Tsupply - Texhaust) * Operating Hours
      • Where:
        • Esavings = Energy saved (Joules)
        • Q = Airflow rate (m3/s)
        • ρ = Air density (kg/m3)
        • Cp = Specific heat of air (J/kg·K)
        • Tsupply = supply air temperature❓❓ (°C)
        • Texhaust = Exhaust air temperature (°C)

• 3.4 Design Considerations for Ventilation Systems:

  • Ventilation rate: The amount of fresh air that needs to be supplied to the building.

    • ASHRAE Standard 62.1: Specifies minimum ventilation rates for different types of buildings.

  • Air distribution: How air is distributed throughout the building.

    • Proper air distribution ensures that fresh air reaches all areas of the building.

  • Filtration: Removing pollutants from the air.

    • High-efficiency particulate air (HEPA) filters are effective in removing small particles from the air.

  • Control systems: Automatically adjust ventilation rates based on occupancy and environmental conditions.

    • CO2 sensors can be used to monitor occupancy levels and adjust ventilation rates accordingly.

4. Case Studies and Examples

• Case Study 1: LEED-Certified Office Building

  • Description: A high-rise office building that achieved LEED Platinum certification.

  • Green features: High-performance building envelope, high-efficiency HVAC systems, rainwater harvesting, and green roof.

  • Appraisal results: The building commanded higher rental rates and sale price compared to conventional office buildings in the same market.

• Case Study 2: Net-Zero Energy Home

  • Description: A single-family home that generates as much energy as it consumes.

  • Green features: Solar PV system, high levels of insulation, and energy-efficient appliances.

  • Appraisal results: The home had a higher market value and faster sales time compared to similar homes without net-zero energy features.

• Experiment: Measuring Airflow Rates in a Classroom

  • Objective: To measure the airflow rates in a classroom with and without mechanical ventilation.

  • Materials: Anemometer, measuring tape, and stopwatch.

  • Procedure: Measure the dimensions of the classroom and the airflow rate through the windows and vents with and without the mechanical ventilation system operating.

  • Results: Compare the airflow rates with and without mechanical ventilation. Determine if the ventilation system is providing adequate fresh air for the occupants.

5. Conclusion

Green building systems offer numerous benefits, including reduced environmental impact, improved occupant health, and increased property value. Appraising green buildings requires considering the unique features and benefits that contribute to their value. Ventilation is a critical component of green building design, ensuring healthy indoor air quality and thermal comfort. By understanding the features, appraisal methods, and ventilation strategies discussed in this chapter, professionals can effectively design, evaluate, and promote green building systems.