Cost Simulation of a High Rise Using
Thermal Dynamic Window System
Evaluating the planned high rise versus an alternate use of IQ Radiant Glass
After reviewing the partial Progress Architectural and Mechanical Plans and Permit sets, we would like to offer the following items for consideration to compare and contrast heating the glazed building envelope with electrically heated glazing systems versus natural gas mechanical heating systems for this project:
The installed cost of a natural gas steam/hot water distribution system is approximately equal to the installed cost of a heated glazing system for the entirety of this building’s thermal envelope.
Annual Energy Operating Cost
Using electrically heated glazing systems will save approximately $390,000.00 per year (a 25% annual energy savings).
A heated glazing system will offer the best means of condensation avoidance in high humidity spaces such as the Pool and Spa areas.
Building Temperature and Building Management Control
Electrically heated glass provides controllers with “software points” with glazing panel pane by pane resolution of control. Steam/hot water heating of glass panes will require extensive valve control, with remote sensors and floor by floor control panels. For cost sake, mechanical control systems using “hardware” points could never match that of electronically controlled systems. We believe this is self-evident and requires no additional justification.
Maintenance Cost & Longevity of Heated Glazing Systems
We believe that since Heated Window Glazing Systems have no mechanical moving parts and require little or no annual maintenance, an annual savings of $500,000.00 a year can be anticipated.
A building with no fossil fuels and only electrically heated systems the electrical utility can be sourced from solar or wind powered sources, thereby reducing the building carbon foot print from 32,596,368 lbs. CO2 per year to zero.
We believe the following pages support our opinion that a Heated Glazing System will provide an annual savings to the Owner of at least $890,000.00.
NATURAL GAS STEAM/HOT WATER HEAT INSTALLED COST BUDGET ESTIMATE
NOTE ON CONDENSATE AVOIDANCE:
The first consideration for using heated glass systems for this project is condensation avoidance in the Spa & Pool areas. We believe electrically heated glass systems will prove to be essential for a cost effective and low maintenance system to avoid condensation.
As you know pool and spa areas are typically heated to a few degrees above the pool water temperature to reduce the evaporation and energy loss. Most pool room conditioning systems are designed to keep the relative humidity of the space below 60%. Assuming the pool/spa water is heated to 80°F the room maintained at 83°F DB and 72°F WB, the dew point temperature in this space would be 71°F DB. Since the building envelope is glass, condensation would be problematic.
Firstly, the mechanical and architectural plans indicate a system utilizing an insulated double glazed exterior with a ventilated double façade created by an interior glazing monolithic glass panel. The heat source for this double façade is a hot water fin tube heater. We believe this system will prove problematic for several reasons.
The cavity between the exterior insulated glazing and the interior monolithic glass panel will, almost certainly permit water vapor migration from the pool/spa air space (from the start or at least eventually) allowing condensation to occur on the interior side of the insulated glazing system. The heat source to offset this is on the interior side of monolithic pane will have little influence on the air cavity temperature between the glazing panels.
The surface temperature of the aluminum mullion between the glazing systems (inside the ventilated façade) will almost certainly be uncontrollable and will likely experience condensation on ASHRAE design temperature days for this climatic area.
The fin tube hydronic system will likely be a series loop water piping system, with limited points for control valves and temperature sensors to regulate glazing surface temperature. Accordingly, the water loops to these hydronic circuits will likely be controlled by either indoor/outdoor temperature reset, or at best, proximity air or glazing surface temperatures. Pool atmospheric chemical conditions rapidly corrode delicate electronic sensors.
Secondly, it is our understanding a duct sox air delivery system is being considered as an air delivery system in the pool/spa areas for condensate avoidance. We question how a central poolroom environmental system utilizing a fabric duct system can possibly keep the 42 foot high glazing and aluminum mullion system above the dew point temperature of 71°F DB on a design temperature day of 11°F DB.
We believe the only practical means of keeping all glazing and mullion surfaces above dew point in the Spa and Pool areas is with an electrically heated and temperature controlled glazing system.