Timothy R. Nolan
Mechanical
Consultant Unknown
The BondStreetWharf
Baltimore, Maryland
September 18, 2002
ASHRAE Standard 62 Report
Executive Summary
The BondStreetWharf hassix stories and is 216,000 sq ft. The second to the sixth floors have two AHU, one for the north side and the other for the south. The first floor has one AHU on the south side. Using ASHRAE Standard 62-2001 to evaluate the raised floor mechanical system,I found that the spaces were a small amount below the design criteria. They were 1% to 15% below the required outdoor air requirements. From the third to sixth floors and the second floor south, the critical space is the open office space. This space has the largest concentration of people per square foot. On the second floor north AHU, the critical space is the office lobby on the first floor. The lobby space receives the most people and transfer air through doors. Once again, there is a large concentration of people in one space making it the critical space. The calculated total supply air from each air handler is a third of the design output. This might have been an added safety factor depending on how the space will be used.
Assumptions
On the first floor, there is retail space not designated to a type. They want to get a restaurant and another shop to fill the space. There is outdoor air ducts ready for future use and shaft space for more ducts if needed. I assumed two spaces were clothes retail and the other to be a restaurant. The kitchen was 100% OA and would be the critical space.
AHU-2N supplies the second floor north and the lobby, electrical distribution room and emergency generator room on the first floor. I assumed the office lobby to be a reception area.
I excluded the bathrooms because they receive transfer air from the open office space.
The electrical and telecom rooms have VAV terminal units underneath the floor. I assumed they supplied these rooms.
Equal mixing and distribution in the raised floor system.
Timothy R. Nolan
Mechanical
Consultant Unknown
The BondStreetWharf
Baltimore, Maryland
September 18, 2002
Major Differences
The Ventilation Rate Procedure and Indoor Air Quality Procedure both determine the minimum outdoor air required to control the amount of contaminates in the air. The Ventilation Rate Procedure determines the minimum outdoor air by the square footage or total occupancy in aspace. Indoor Air Quality directly measures the concentration of contaminants in the air for a space. A designer using the Ventilation Rate Procedure may over or under size the amount of outdoor air by using different assumption. When using the Ventilation Rate Procedure you should write down your assumptions during the calculation process so everyone knows what your thought process was and what your assumption are.
Another difference between the two is Ventilation Rate Procedure takes into a count multi spaces where Indoor Air Quality usually is for one specific space. Someexamples areauditoriums and gymnasiums. In these spaces, the amount of people will increase dramatically along with contaminates. You need to monitor these spaces alone and place them on a separate system. If you use Ventilation Rate multi-space Procedure it is likely the critical space may not be the auditorium or gymnasium and would be a smaller space with a higher concentration of occupancy per square foot. Therefore the auditorium or gymnasium would be deficient in outdoor air and would be suffocating to be in.
When designing a building that has spaces that are similar and can be placed on the same system, you can use the Ventilation Rate Procedure. This method is cost effective and is used in many of today’s buildings. When spaces are more critical you should use the Indoor Air Quality Procedure to evaluate the amount of outdoor air. This method costs more but will improve comfort levels in these spaces. It is also important to use the Indoor Air Quality Procedure because of sick building syndrome. Sick building syndrome is a building related illness caused by contaminates from the building. This is becoming a concern with old and new building owners.
Timothy R. Nolan
Mechanical
Consultant Unknown
The BondStreetWharf
Baltimore, Maryland
September 18, 2002
Calculations
1)Measured areas off of drawings.
2)Looked at ASHRAE for cfm/person or cfm/sq ft.
3)Multiplied area time cfm/person or cfm/sq ft to obtain minimum outdoor air required.
4)Found critical space for each AHU by (min OA) / SA for each space.
5)Found X value by (total OA) / (total SA).
6)Multiplied X value times the total SA to a space to find the un-correct OA.
7)Then used multiple space equation [Y= X / (1+X-Z)] to get Y value.
8)Multiplied Y value times the total SA to a space to find the correct OA.
1