Holdfast Training Services Trial Blog

Fort Indiantown Gap (FtIG) is a U.S. Army post primarily used as the Pennsylvania National Guard Headquarters and main training facility about 25 miles North East of Harrisburg. It is also the location of another project I am involved in/running.

Map showing Fort Indiantown Gap

As part of America’s war on greenhouse gas emissions, or perhaps their fear of other people controlling energy resources, FtIG is converting from a reliance on oil to natural gas as it’s main form of heating energy. This is in common with a lot of other Department of Defense (DoD) sites and is as a result of an executive order issued by the great environmentalist George Bush. From this two questions should spring to mind; the first of which being how old is the executive order, well it’s from 2007. The second possibly has more to do with George Bush’s politics and for that discussion I will have to refer you to the kebab shop in Kingston upon Thames.

Either way, as a result one of the boiler rooms at FtIG requires a replacement of its 2 x heating boilers, domestic hot water boiler, their pumps and most of the pipework within the plant room as well as cleaning the chiller pipework. The existing system was installed in 1975 and has been somewhat tampered with, although not completely refitted it appears so, with a 15 year design life, is on its last legs. Below the diagram shows the as built drawings of the heating and chilled water systems with my annotations for the summer and winter conditions:

Winter Condition

These systems have three outputs, as shown in the winter condition: firstly to the underground pipe network feeding the Variable Air Volume (VAV) terminals in the building with either hot or cold water depending on the season. Secondly, due to the removal of the Heating and Ventilation (H&V) Unit (bottom right) a single unit heater is supplied and thirdly the air conditioning unit within the plant room which supplies ducted air into the building. What is significant about this system is mainly that the first output consists of a single, two pipe system supplying either hot or chilled water. Therefore in the seasons of spring and autumn when the requirement of the system is likely to vary between heating and cooling throughout the course of a day the system will have to cool the water within the pipework before having any effect on the building.

So are we going to fix that, hell no! Currently the design is merely to replace like for like despite there being a reasonably simple solution. This appears to be due to the ’colour of the money’. The money funding this project is only supposed to fund improvements in efficiency rather than improvements in performance.

To see what the actual cost would be I decided to do a calculation, so assuming the 3” pipe is 1km long, the water is of density 1000kg/m³ and would have to be cooled from 80°C to 10°C.

Water Volume in pipes: V=length x π r² = 1000 x π 0.0375² = 4.42m³

Water Mass in pipes: m = ρV = 1000 x 4.42 = 4420kg

Heat loss required: Q = mCΔT = 4420 x 4.18 x(80 – 10) = 1293MJ

Converted to kWh as that is what electricity is billed in: 1293000/3600 = 359kWh

Assuming the fort pays the same as I do per kWh the cost is 13c/kWh, therefore:

0.13 x 359 = $46.72 per time the system is cooled down. So if this occurs 30 times during each spring and the same each autumn, that is 60 occurrences per year, costing $2,803.

Whilst in ‘calculation mode’ I thought it worth looking at the time it would take to cool the loop down to determine the response of the system. So assuming a 60 ton chiller (from a combination of the drawings and a SWAG):

Power in KW = 3.5 x Power in tons = 3.5 x 60 = 210kW

t = Q/P = 1293000/210 = 6,161s or 1:43

So at the point that the system determines to go from heating to cooling it will take nearly 2 hours for the system to start to have an effect, not ideal on a hot spring day. In payback period terms it is probably in the same region as Mike’s windows. However, like Mike’s windows the system will probably be in position for long past that time period and in the mean time it will produce an enhanced product and save the environment a little, which would surely be good enough reasons on their own. So what, well it seems like a sensible idea to me but I imagine the issue of the funding will be what prevents a logical decision being made. Sadly if we don’t implement something it will be a kick in the teeth for me on competence E3 but hopefully my case here is an element of evidence enough for that!

In other news Jo is now the proud owner of a Maryland State drivers licence. Her test consisted of backing into a parking bay followed by a short cruise around the block completing both left and right turns at four way stops. No traffic lights and she didn’t get above 25mph. Jo was expecting to have to parallel park the car at some point but apparently that was taken out of the test last week because too many people were failing; words fail me!