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Guide to Demand Controller Applications (On-Demand Pump Controls)

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Useful guide or white paper that describes applications for demand controllers (On-Demand Pump Controls). It discusses good applications, case studies, and other information that may be useful when looking at demand controls for commercial and multifamily buildings. This will describe the energy savings and efficiency gains by employing this pump control strategy in hot water distribution.

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Guide to Demand Controller Applications (On-Demand Pump Controls)

  1. 1. Reducing  High  Energy  Bills  Related  To   Central  Water  Heating  Systems  –     A  Guide  to  Enovative™  Demand   Controller  Applications   Identifying  Good  Building  Applications,  Estimating  Savings,  Supporting  Data     The  Enovative  Demand  Controller  is  a  recirculation  pump  control  used  for  domestic   hot  water  that  operates  based  on  user  demand  within  the  building  as  well  as   temperature  of  the  recirculation  loop.  It  will  run  intermittently,  as  needed,   throughout  the  day  running  an  average  of  1  hour  vs.  the  24/7  continuous  pumps   that  are  currently  in  use.       By  operating  in  this  fashion,  the  recirculation  loop  temperature  is  allowed  to  cool   during  periods  of  non-­‐use,  slowing  down  heat  losses,  and  kick-­‐starts  the   temperature  back  to  normal  when  someone  does  need  hot  water.  The  pump   electricity  is  reduced  by  over  90%,  but  more  importantly,  the  heat  radiating  from   the  recirculation  loop  is  reduced  by  over  50%,  which  can  result  in  an  overall  10  to   30%  reduction  in  the  water  heating  energy  consumption.       Refer  to  the  following  sections  to  learn  about  the  best  applications  of  the  Demand   Controller  and  simple  ways  to  estimate  savings.     Best  Building  Types:   Here  are  some  general  indications  of  the  type  of  buildings  that  work  well.  It  is  split   into  3  tiers,  but  there  is  no  fine  line  between  the  tiers  as  specific  characteristics  of  a   certain  building  type  can  influence  the  savings.   Tier  1  –  Highest  Impact:     Multifamily  (20+  units),  Hotels,  Motels,  Condos,  Dorms,  Barracks,  Hospitals,  Some   industrial   Tier  2  –  Mid  Impact:     Multifamily  (under  20  units),  Gyms,  K-­‐12,  Airports,  Arenas,  large  offices     Tier  3  –  Lower  Impact:     Small  Healthcare,  small  office,  retail  store,  supermarket,  restaurants,  warehouse  
  2. 2. Characteristics  of  Ideal  Applications:   Since  this  is  a  technology  that  primarily  slows  down  heat  losses  from  the   recirculation  loop,  The  more  piping  there  is,  the  greater  the  distance  that  the  pipe   travels  throughout  the  building,  the  larger  the  difference  between  the  temperature   of  the  pipe  (which  is  close  to  the  temperature  setpoint  of  the  system  120  to  140   degrees  F)  and  the  surrounding  environment  (ambient  air  temp,  cold  ground  temp  if   in  ground,  etc…),  the  higher  the  savings.  Look  for  these  attributes  to  find  the  slam   dunk  applications:     • Higher  Domestic  Hot  Water  Use   • Large  Structures  with  water  use  spread  out     • Inefficient  Water  Heaters  (Sediment,  low  EF  rating,  etc..)   • High  Water  Heater  Temperatures  Needed  or  Wanted   • Pipe  running  in  unconditioned  spaces  (crawl  spaces,  garages,  outdoors),   underground  or  under  slab   • Many  Gallons  of  Hot  Water  Storage  (200+)   • Exposed  Piping  that  you  can  place  the  temp  sensor  at  the  last  unit  on  the   loop*     *If  the  loop  is  exposed  (such  as  in  a  subterranean  garage),  you  can  often  times   identify  the  last  point  at  which  hot  water  is  needed  and  wire  the  temperature  sensor   which  shuts  off  the  unit  at  this  point.  In  a  scenario  like  this,  you  can  cut  off  hundreds   of  feet  of  heated  pipe  that  is  unnecessarily  hot.   Characteristics  of  Energy  Wasteful  Recirculation  Loops:   • Not  Insulated   • Running  24/7   • Oversized  Pump   • Long  return  lines  or  a  far  distance  between  the  boiler  room  and  the  last   fixture  that  uses  hot  water  on  the  loop   • Large  pipe  diameter  sizes   • Running  through  unconditioned  space  or  other  materials  that  act  as  heat   sinks  such  as  underground,  under  slab,  etc.   • Long  branches  off  the  main  loop  before  it  gets  to  the  fixtures*   • Broken  Pumps*   • Closed/Broken  Valves*     *items  are  water  wasteful  and  may  or  may  not  be  energy  wasteful   Simple  Ways  To  Estimate  Savings:    
  3. 3. As  the  manufacturer  of  the  Demand  Controller  system,  our  official  savings  claims   are  a  reduction  in  your  water  heating  energy  between  10%  and  30%  and  pump   electricity  reduction  of  more  than  80%.  These  claims  are  dependent  on  the  specific   characteristics  of  the  application.     From  all  the  various  case  studies  conducted  (next  section),  the  most  obvious  trend   has  been  that  a  small  building  will  have  a  high  proportional  saving  (20  to  30%  off   the  water  heater  energy)  while  having  a  relatively  smaller  absolute  energy  saving   value  (400  to  1000  therms),  while  bigger  buildings  have  a  lower  proportional   savings  (10  to  20%)  while  have  a  larger  absolute  energy  saving  value  (1000+   therms).       This  makes  sense  as  the  larger  buildings  will  have  more  frequent  occurrences  of   demand,  therefore  less  down  time  between  uses  to  save  energy.  Whereas  the   smaller  buildings  have  less  frequent  hot  water  events  and  therefore  longer  periods   of  time  to  save  energy.       While  it  can  be  very  tough  to  accurately  model  heat  losses  from  the  loop  (too  many   variables  and  most  are  unknown),  some  general  trends  have  appeared.       The  following  are  some  rules  of  thumb  that  we  use:     • 30  therms  saved  per  unit  per  year     Or  use  the  following  table  to  determine  narrow  in  on  estimating  the  savings  off  a   percent  reduction  from  the  bill.       10%   1000+  therms   15%   500  to  999   20%   300  to    499   25%   299       These  will  be  updated  as  more  data  is  received.       It  should  be  noted  that  estimating  the  pump  electricity  savings  are  much  easier  and   more  accurate,  but  you  need  to  know  the  information  on  the  pump  you  are   replacing.       If  it’s  a  small  pump,  85  watts,  then  the  savings  will  be  around  700  kWh,  if  it’s  a   bigger  pump  (200  watts),  then  the  savings  will  be  around  1600  kWh.  We  have  even   replaced  500  to  800  watt  pumps.  Just  assume  that  with  a  Demand  Controller,  the   pump  will  only  run  about  1  hour  per  day,  compared  to  running  24/7  on  the   conventional,  uncontrolled  pump.  You  can  use  the  nameplate  information  to  figure   out  the  rest  with  some  simple  calculations.  
  4. 4. Water  Efficiency   Recirculation  pumps  are  used  to  reduce  the  wait  time  while  waiting  for  hot  water.     Hot  water  is  available  quickly,  but  with  the  tradeoff  of  tremendous  energy  waste.   This  is  the  dilemma  between  water  efficiency  and  energy  efficiency.  Using  the   Enovative  Demand  Controller  is  the  best  of  both  worlds;  you  get  hot  water  quickly,   but  without  the  energy  waste.  Even  though  the  Demand  Controller  only  runs  on   demand  and  when  there  isn’t  a  suitable  temperature  (above  100°F),  does  not  mean   there  is  the  tradeoff  for  waiting  for  hot  water.  Here’s  why:   • It  only  takes  1  use,  anywhere  in  the  building,  to  prime  the  entire  loop   • A  primed  supply  line  takes  up  to  3  hours  to  fall  below  a  suitable  hot  water   temperature   • By  Default,  the  Demand  Controller  auto-­‐primes  the  loop  every  5  hours   • It  takes  roughly  50  seconds  to  purge  250ft  of  1-­‐1/2”  supply  line,  which  is   only  possible  (to  wait  an  extra  50  seconds)  if  you  are  the  very  last  tenant  on   the  supply  line  AND  it’s  been  about  3  hours  since  the  last  hot  water  use  by   anyone  in  the  building,  but  not  more  than  5  hours  since  the  auto-­‐prime   feature  will  have  kicked  in.  The  probability  of  this  chain  of  events  approaches   zero.     • The  Demand  Controller  is  currently  in  thousands  of  buildings  throughout   North  America,  from  luxury  resorts,  to  large  apartment  buildings  with  as   many  as  189  units  on  one  recirculation  loop  without  any  unsolvable  issues.         The  Demand  Controller  saves  water  by  allowing  the  pump  to  fulfill  its  function  of   hot  water  delivery  through  the  loop,  and  test  data  has  in  fact  shown  more  water   savings  than  a  continuous  pump.  Preliminary  studies  thus  far,  in  26  buildings  have   resulted  in  an  average  of  2%  reduction  in  the  buildings  entire  water  use  (Please   note  that  this  data  is  highly  variable).  In  the  Marriott  Case  study,  where  water  meter   reads  were  taken  over  52  weeks,  making  it  the  largest  data  set  in  this  area,  showed  a   4%  reduction  in  water  use  for  the  year.       History  of  Case  Studies:   Here  are  brief  summaries  of  specific  case  studies  conducted  on  the  Enovative   Demand  Controller.  This  is  supporting  data  that  helped  guide  us  towards  the   savings  estimations.  In  total,  data  has  come  from  nearly  100  buildings,  which   is  not  a  big  enough  sample  size  to  be  statistically  sound,  but  more  indicative   of  what  we  would  expect.  Hundreds  of  thousands  of  dollars  were  spent  on   these  studies  with  millions  of  data  points  collected.     The  earliest  installations  of  the  Demand  Controller  happened  in  2005,  and  that’s   when  case  studies  started  being  conducted  both  in-­‐house  and  by  third  parties  such   as  utilities,  municipalities,  and  state  governments.  The  beta  title  was  lifted  in  2010  
  5. 5. after  more  than  5  years  of  produce  development,  testing,  and  more  product   improvements.       2006:     • The  state  of  California  tested  the  units  during  2005  and  2006  by  funding  a   third-­‐party  engineering  firm  to  study  hot  water  systems  in  multifamily   buildings.  They  tested  three  buildings  showing  close  to  40%  savings.  Being   the  earliest  tests  of  this  kind,  some  of  the  methodology  is  flawed  and  a  new   study  was  started.       • During  this  same  period,  a  Stanford  dorm  tried  out  the  product  and  reported   20%  savings.  Also  a  retirement  home  installed  a  unit  in  one  building  and  did   not  install  it  in  the  other  identical  buildings.  Five  years  of  billing  data  showed   the  building  with  the  Demand  Controller  to  consistently  use  substantially   less  energy.   2007:     • A  La  Quinta  Inn  in  Duluth,  Georgia  bought  a  unit  and  wrote  a  letter  stating   their  bills  dropped  20%  when  compared  to  the  previous  year.    Enovative  also   did  its  first  in-­‐house  case  study  using  data  loggers  and  scientific  method  to   show  a  building  was  saving  30%  off  its  bill.  This  was  a  50  unit  building  in  Los   Angeles.     2008:     • Enovative  sent  out  staff  to  Washington  DC  to  test  a  17  unit  and  a  34  units   multifamily  building.  The  savings  were  calculated  at  15%  and  the  dollar   savings  where  $1,100  and  $1,400  per  year.     2009:     • In  2009,  Southern  California  Gas  Company  launched  a  third  party  program   rebating  the  Demand  Controller.  Part  of  the  funding  was  a  follow  up  study  on   35  multifamily  buildings.  The  average  savings  was  1,526  therms  per  year  and   1,236  kWh  per  year,  which  was  an  overall  reduction  of  16%.  The  table  of   savings  for  each  building  is  shown  at  the  end  of  this  document.    This  data  was   reported  in  a  2009  Monitoring  Report.       • Enovative  also  conducted  a  study  on  a  6  unit  building  in  San  Francisco  that   also  had  solar  water  heating.  This  building  showed  a  30%  reduction  on  top  of   the  savings  being  achieved  by  the  solar  energy.  ODE  Report,  Marriott  Started,   St.  Francis  Sq.,  Bluestone    
  6. 6. • A  customer  in  New  York  also  conducted  his  own  study  and  wrote  a  letter   explaining  how  he  tracked  his  savings  of  $1,100  a  year  in  water  heater   savings,  but  an  additional  $200  in  pump  electricity  savings.       • Finally,  a  year-­‐long  case  study  at  a  Marriott  Vacation  Club  resort  was  started   and  tracked  by  Southern  California  Gas  Company.       2010:     • The  Marriott  study  was  concluding  after  a  year  showing  a  12%  reduction  in   water  heating,  which  was  high  considering  the  Palm  Springs  climate.  The   building  had  12  rooms.       • Enovative  also  concluded  a  study  on  a  similar  building,  Welk  Resorts  in  San   Diego.  This  was  an  8-­‐room  building  that  used  electric  water  heaters  so  the   savings  were  18%  and  over  7000  kWh  per  year.       • Another  customer  based  in  the  San  Francisco  area  was  lent  loggers  to  track   their  purchase.  They  faxed  back  results  showing  a  15%  reduction  in  water   heating  and  97%  reduction  in  pump  electricity.  This  was  a  42-­‐unit  condo   building.       • The  continuation  of  the  CA  state  funded  study  reported  on  their  new   findings,  which  was  based  on  32  buildings  throughout  California.  The   Demand  Controller  showed  a  15%  savings  and  outperformed  all  other   control  measures  that  were  studied.       • A  customer  in  Denver,  also  tracking  their  own  savings,  was  able  to  show  a   savings  of  2,400  therms  annually  on  a  60  unit  building.       • Further  testing  under  the  rebate  program  by  Southern  California  Gas  showed   savings  between  20  and  30%,  most  of  these  building  were  small  between  8   and  30  units.       • City  of  Anaheim  tested  in  their  City  hall  and  showed  savings  as  high  as  50%,   but  since  the  system  only  serviced  two  break  rooms  and  a  bathroom,  the   resulting  payback  was  still  high  due  to  the  low  hot  water  consumption.       Here  is  a  table  pulled  from  the  2009  monitoring  report  on  35  buildings  tested:  
  7. 7.        

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