News
  1. Protect Your Building From Copper Theft!
  2. Structural Concerns when Replacing Rooftop HVAC Equipment
  3. Heat Wave

Protect Your Building From Copper Theft!
Copper theft is at an all time high, and it’s not just limited to easily accessed copper such as condensate lines. With the rise in copper prices, thieves are digging deeper for their stolen treasure.

The damage to buildings and equipment caused by copper theft is reaching catastrophic figures. Electrical panels are being stripped, and HVAC units have been completely torn apart to access coils and motors containing copper. The pictures below represent once working units that were placed ground level without any fencing or protection, and a new 50-ton unit that had not even made it to the roof.

AirCom encourages you to take inventory of your exposure to copper thieves. This is particularly important if you have a single story building, a vacant building, or equipment that is located on a ground level equipment pad.

        
        
        



Structural Concerns When Replacing Rooftop HVAC Equipment
Do not be surprised if your air conditioning unit replacement triggers a structural upgrade of your building. This is a growing s tatistic which is shared among all building owners and tenants in the Silicon Valley which expect a relatively easy replacement of a HVAC unit which has meet the end of it's lifespan or intend to add additional capacity to their building. Advance Design Consultants, has been working with Aircom on providing mechanical and structural solutions to these customers to ease the pain that city requirements may inflict on unsuspecting buildings.

When you apply for permit to replace or add an air conditioning unit, the City will most likely require structural drawings and calculations to review the existing structure for its capacity to support the new equipment even if it weighs the same as the old unit. The aim is to determine if it meets the requirements of the current approved 1997 Uniform Building Code. This current building code has much more stringent loading requirements, and as such, if a building was designed and built before 1996, then the building is at risk of requiring local structural upgrades to meet the current code. Unfortunately, there is no grandfather clause in the code, or honored by any city that will allow the replacement of an air conditioning unit "in kind".

ADC and Aircom's experience seems to pertain to the specific cases of tilted-up concrete buildings. These building have a wood diaphragm roof supported on the walls and internal columns, with of glulam girders and 2x beams and purlins covered with plywood sheathing and roofing material. It is often found that the wooden members do not meet the load combination Dead Load (Roof Equipment) + Roof Live Load (20 pounds per square foot) required by the code.

The reasons for this might be due to the following:
  1. The current code load requirements might be stricter than the code used in the original design of the structures.
  2. The requirements of the NDS code for wood design have changed, especially when referring to the strength of the species wood members and the number of species now considered.
  3. Large spans in the order of 50 feet or larger are usually found in this type of structure and the glulam members sized to the minimum required.
  4. Spacing of the beams and purlins are maximized to reduce the building construction cost, and did not allow contingency for future changes in equipment.
  5. The information available to review the structures, in most cases, is not sufficient to determine the exact type of glulam, or the species of wood used, the type of plywood, the thickness and the type of roofing material, etc. Which require conservative assumptions to be made by the structural engineer when performing the evaluations.
  6. Occupancy of the building does not permit economic solutions such as adding additional columns to reduce spans and therefore increase the capacity of the existing members.
What you may do to mitigate this concern:
  1. Never pre-order rooftop equipment without checking if the structure is capable of supporting the new equipment without major upgrades.
  2. Choose carefully the best equipment to fit your building, including performance, weight, and shape.
  3. Determine an alternative location for your new equipment closer to building columns.
  4. Find a Contractor with an open mind that will find the best solution for your facility.
ADC has been working through structural solutions to minimize the financial impact that the customer has to absorb over what a standard unit replacement would typically cost. If you would like more information please feel free to contact Aircom, or ADC at 408-297-1881 or e-mail ADC at melissa@adcengineers.com.

About Advance Design Consultants, Inc.:
Advance Design Consultants has been providing multi-discipline engineering services to the Hi-tech, Commercial, Industrial, and Residential sectors since 1984. ADC is a full service engineering firm providing Mechanical, Electrical, Plumbing and Structural engineering disciplines. Our firm possesses a tremendous wealth of mature knowledge and its level of experience and attention to detail surpasses most industry leaders. For the last 22 years,ADC has been providing quality facility surveys, preparation of studies, engineering, detail designs, cost estimates and construction support services.

Advance Design Consultants, Inc.
998 Park Ave.
San Jose, CA 95126
408-297-1881
www.adcengineers.com

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 Heat Wave
 July's record setting heat-wave was the longest and hottest in 30-years! Although it's unlikely to have such extreme temperatures in the near future, we would like to pass on some valuable information that can help keep you cool when the weather gets hot. And likely save you money!

First, some technical background. Air Conditioning units are sized for heat-load within a facility, and limited to size by building codes within various regions. For example, a building in Seattle, WA would not have the same AC units if it were located in Tempe, AZ. Even though the internal requirements may be the same, the efficiency of the AC units has to be much greater in Tempe because the ambient temperature on the roof is much greater. How does the temperature on the roof affect the temperature in the building you ask? Once the temperature on a roof has exceeded a unit's designed optimal cooling capacity to provide 68º to 72º cooling, the unit's efficiency begins a steady decline as the outdoor temperatures rise. Bringing this example home, Air Conditioning units in our region are rated for 95º outdoor temperatures. When the temperature on a roof reaches 96º, you loose about 1% efficiency (ability to provide cooling). For each degree, another 1% efficiency is lost. A few degrees over 95º (or a small drop in efficiency) is not a big deal-or even noticeable. But when the temperatures reach 110º and above for several days in a row, we might as well be in Tempe, AZ.

During this past week, rooftop temperatures (the actual temperature at the units as opposed to the temperature reported by the weatherman) reached in excess of 130º. This represented an efficiency loss of 35%. Even newer equipment in perfect working condition can't sustain optimal cooling in this environment. Couple this with older units that have simply lost efficiency because of age, wear and tear, a 35% additional loss renders these units incapable of cooling their subject spaces anywhere near 68º -72º.

So why not put more efficient units on the roof and be prepared for this type of heat-wave? Enter Title 24. As mentioned earlier, units are rated based on regions. With energy at a premium, installing a unit capable of 100% efficiency in say, 110º weather, would waste energy if in fact the temperatures were on average far below. Thus, we have units rated at 95º based on our average climate. Anything higher would not be approved.

Understanding the limitations of your air conditioning may help avoid service calls, and prepare you for extreme temperatures in the future. Easily a third of our service calls this week were related to t-stats being miss-adjusted (usually turned too far down) and units working at their fullest capacity with no breakdown or problem-other than lost efficiency as explained above. So here are some tips that can help in the event of another week of high temperatures:
  1. Ensure t-stats do not get set below 68º. If an AC unit can't cool a room to 68º, setting the t-stat lower will not make it cooler, it will simply break the AC unit. And then there will be no cooling at all.
  2. If a request for a service call is made because a room won't get below 74º to 76º, and the temperature outside is 110º, it is very likely there is nothing wrong with the AC Unit. Most likely the unit is simply maxed. You made need to call us to verify the working condition of the unit, but this information may save you the cost of a service call.
  3. If you did not elect to include coil cleaning in your PM, ensure all proposals for coil cleaning are approved prior to the summer months. Dirty condenser coils are one of the biggest contributors to a unit's loss of efficiency. And dirty coils drive up energy consumption and costs.
  4. Complete all compressor annuals in the Spring. Annuals ensure equipment is running at optimal efficiency. Performing annuals before the summer months provides for time to make repairs, if necessary, before a buildings comfort becomes a problem.
  5. Ensure all repairs are made on a timely basis. Many of the service calls we answered were to address issues we had previously proposed. Many of these items were not seen as priorities in the milder weather, but became severe problems in the extreme heat.
We hope you find this information helpful. We are constantly looking for ways to improve our service and maintain a commitment to our customers that exceeds expectations. Please call me anytime with your questions, comments or concerns.

Thank you,

Dan Munier
Director of Operations

PS. For additional information and a PG&E White Paper on equipment efficiency, please give us a call.

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