[Bldg-sim] Modeling Hot Water Use

[JRR]

Hi;

I'm working up a solar DHW system for a high rise apartment building 
with roughly 550 units.
The collectors have to be on the roof, and the mechanical room is on the 
roof.
This limits the weight of tankage , etc., so I'm trying an "on the fly"  
design where the solar
tempers the service entrance water and the building riser return as 
available.

The trick to providing the maximum amount of heat is to figure out how 
much heat
has to be stored mid-day in Summer without boiling the service tank.
I got hourly hot water demand data from

"Domestic hot Water System Modeling for the design of Energy Efficient 
Systems"
Joe Wiehagen, Jeannie Leggett Sikora, NAHB, 2002.

This document was very helpful, presenting  a low use case and a high 
use case, but it
did NOT provide statistical support for the low and high cases...  That 
is are they 3 Sigma
cases??  2 Sigma cases?? What's the standard deviation of the HW demand ??

I talked to the local water authority and their observations are that 
much larger short term
transient spikes of water use occur in cold water supply compared to hot 
water supply.

John R Ross III  PE
Westwind Corporation
Vienna, VA 22182-1958
energy.wwind at cox.net