LEED certification

5.1 Overview

A “Green Building” is the measure of how sustainable a building is constructed. This is done by optimizing the design and construction of the building and minimizing the operations and maintenance. The United States Green Building Council (USGC) is the US government organization that developed the “Green Building” rating system through the LEED committee, Leadership in Energy and Environmental Design. The LEED committee provides the standards and performance criteria for certifying a sustainable design. The “Green Building” standards help improve the quality of buildings their impact on the environment, and promote environmental leadership in the building industry. Though a point system, LEED addresses six development and construction processes when rating a building as “Green”. These areas include sustainable sites, water efficiency, energy and atmosphere, materials and resources, indoor environmental quality and innovation and design process. Each of the six categories has certain prerequisites that are required and must be achieve to be considered for LEED certification. LEED awards points for accomplishing certain criteria in each of the six categories. A minimum of 26 points is needed for the building to be recognized as a “Green Building”.

The six sections addressed by the LEED certification focuses on different development processes of the construction of the building. The HVAC system is only a portion of the development processes that LEED focuses on for certification. The design of the HVAC system of the Miami Green buildings will concentrate on the Energy and Atmosphere and the Indoor environmental quality sections. In this chapter, the criteria for these sections and the methods used to achieve the points will be described.

5.2 Energy and Atmosphere (EA)

The Energy and Atmosphere prerequisites that are required from the HVAC design are the “Minimum Energy Performance” and “Fundamental Refrigerant Management”. The Minimum Energy Performance (EA Prerequisite 2) standard creates an energy baseline for a construction depending on the building usage set by ASHRAE standard 90.1. This standard focuses on establishing a minimum level of energy efficiency for the proposed building and systems. The Fundamental Refrigerant Management (EA Prerequisite 2) standard aims towards reducing ozone depletion. The use of CFC, Chlorofluorocarbon based refrigerants is prohibited for new constructions. This is done to phase out refrigerants such as R-22 that once was commonly used in HVAC systems and is responsible for ozone depletion due to its release of CFC into the atmosphere. The HVAC system of the Miami Green Building will be designed to use refrigerant R-410a which is not CFC-based.

The main focus on the Miami Green HVAC design project is to maximize energy efficiency. In the Energy and Atmosphere section of the LEED certification, credit 1 awards points dependant upon the percentage of energy usage reduced. This credit focuses on achieving increasing levels of energy performance above the standard and reducing economic impacts associated with excessive energy use. The design of the Miami Green HVAC system will improve the minimum energy usage set by ASHRAE standard 90.1 by 25.28% to collect 5 points from this section. This improvement of energy usage was the focus of Chapter 3. Summing the total energy cost of the Miami Green building, E-quest calculated and energy that the usage of 2,820,000 kWh was needed. By using more efficient lighting and insulating glaze on the windows and better insulation on the envelope the energy usage was decreased. Also a more efficient HVAC system of 14 EER (Energy Efficiency Ratio) was used. The baseline

The forth credit in the Energy and Atmosphere section deals with “Enhanced Refrigerant Management (EA Credit 4). Miami Green achieves this credit by using packaged units designed to use refrigerant R-410a. Using this refrigerant drastically reduces ozone depletion. Also, using packaged units reduces the quantity of the refrigerant used, further reducing the environmental impact. The combined effect of these two factors gives Miami Green a point for EA credit 4.

5.3 Indoor Environmental Quality (EQ)

The next section that the Miami Green Building HVAC system design will focus on is the Indoor Environmental Quality (EQ). The prerequisite that is required is to provide a “Minimum Indoor Air Quality” (EQ Prerequisite 1). This prerequisite is mandated to contribute to the comfort and well being of the occupants of the building. ASHRAE standard 62.1 set minimum requirements of ventilation for acceptable indoor air quality. Mechanical ventilation systems installed during core and shell construction will be capable of meeting projected ventilation levels based on tenant requirements.

The first credit in this section (EQ Credit 1) deals with “Outdoor Air Delivery Monitoring’. To achieve this credit Miami Green will have a mechanical room with computers equipped to monitor many sensors that are associated with the HVAC system. Naturally ventilated areas in the Miami green project such as the Garage will have CO2 and CO sensors to monitor the concentrations of carbon dioxide and carbon monoxide. Fans will be used to circulate and ventilate outdoor air into these areas. The sensors will alert the operators in the Mechanical room if an excess of harmful gasses is present were cautions will be addressed. Mechanical ventilation systems will be placed properly throughout the structure. These ventilation systems will provide direct air flow do meet at least the minimum ventilation requirements. The ventilation systems will have sensors to monitor the airflow through the

system. The sensors will also alert the mechanical room if the minimum requirement is not met. If this were to occur, proper cautions will be addressed. This ventilation monitoring system receives a point for Outdoor Air Delivery Monitoring. The Ventilating systems for the Miami Green project will be set to provide airflow of 30 percent over the minimum required by

ASHRAE section 62.1. The increased airflow will provide the occupants with better quality air and achieves a LEED point for increased ventilation (EQ Credit 2).

When the construction of a building is complete the quality of the air initially in the building is poor due to the processes of the construction of the building. An Indoor Air Quality Management Plan is made to control the air quality during construction and preoccupancy periods. This plan is used to take action in following air quality standards and protect absorption materials from moisture damage. Once the Miami Green Building is constructed, a flush process will be performed. This process includes flushing the building with 100% outside air for 10 days and replacing all filtration systems prior to occupancy. This flush process achieves one point towards the LEED certification (EQ Credit 3).

Finally the air filters used in the packaged units will be of a minimum efficiency rating value of 13. These air filters will be applied to both the return air and the outside air which is delivered as supply air. Using these filters achieves another point towards the LEED certification (EQ Credit 5).

5.4 Conclusion

These HVAC designs outlined above conclude that a total of 10 points will be achieved towards the LEED certification that is associated with the HVAC design. Also another point can be awarded for having the occupants of the building complete a survey after six months of the building occupancy. This survey will ask for a detailed description of the occupant’s view of the

to maximize the occupant’s thermal comfort. The 11 points accumulated is almost half of the points necessary to certify the buildings as “Green”. The remainder of the points can be achieved through architectural and construction processes. Criteria focusing Sustainable sites, Water Efficiency, and Material and Resources are sections which the architects design and contractor’s equipment can achieve the remaining points necessary for LEED certification.

Table 5.1 - LEED Credit Summary

Section Criteria Points Requirements

Minimum Energy Performance PreReq Fundamental Refrigerant Management PreReq Optimize Energy Performance 5

Reduce building energy cost by 24.5%

Energy and Atmosphere

Enhance Refrigerant

Management 1 Use Zero CFC-based refrigerants

Minimum IAQ Performance PreReq

Outdoor Air Delivery

Monitoring 1 Measure outdoor airflow

Increased Ventilation 1 increase ventilation by 30%

Construction IAQ

Management Plan 1 perform Building "flush out"

Indoor Chemical and

Pollutant Source Control 1 Use MERV13 filters

Indoor Environmental Quality Thermal Comfort Verification 1

Create occupant thermal comfort survey