Higher productivity and lower energy cost through better indoor climate and life cycle cost analysis

Transcription

1 Higher productivity and lower energy cost through better indoor climate and life cycle cost analysis Dennis Johansson Forskning och utveckling Swegon AB Byggnadsfysik/Installationsteknik LTH

2 Content Higher productivity and lower energy cost through better indoor climate and LCC analysis Introduction how to solve both indoor climate and lower energy use Optimisation examples Office School Dwelling Research on input data

3 Background energy use Building sector uses 40% of the used energy in Sweden Like in Europe Relevant to decrease the energy use in the sector Goals are out regarding energy use and CO 2 emissions Examples are the Energy Directive and new Swedish building code Energy is used primarily for Space heating Household electricty (heating?) Common electricty, lighting Cooling Ventilation

4 Indoor climate We are approximately 90% indoors Temperature, ventilation, lighting Studies show for example that we produce more at higher airflow rates and correct indoor temperature Tanabe, Wargocki, Fanger reduce the level of sick leave with higher airflow rates Milton, Seppänen, Fisk lower the prevalence of asthma and allergy - Bornehag, Hägerhed Engman, Sundell learn faster with higher airflow rate and correct indoor temperature Wyon, Wargocki Hypotheses We are influenced by the indoor climate There is a need for a system perspective including the entire building and user

5 Energy use and indoor climate Often conflicts Indoor climate systems and lighting uses energy What level is right? How to value the indoor climate? How to value outdoor environmental load? Detailed demands? Functional demands? Life cycle economics?

6 Examples of optimisation Assume that we can value the indoor climate through productivity and health as a function of outdoor airflow rate indoor temperature Costs for indoor climate systems and the running costs including maintenance and energy can be calculated Different systems can provide the indoor climate The sum of these costs can give optimal airflow rate and indoor temperature

7 Content Higher productivity and lower energy cost through better indoor climate and LCC analysis Introduction how to solve both indoor climate and lower energy use Optimisation examples Office School Dwelling Research on input data

8 Office building - goals LCC for heating, cooling and ventilation systems Theoretical office building with one corridor and four storeys Including costs for productivity related to airflow rate and temperature respectively

9 LCC year life span Net present value discount interest rate 1% electricity, 2% heat, 3% other Included costs Initial Energy Maintenance Repair Space loss Cost to represent health and productivity ProLive computer program for LCC 2005 Salary cost 200 SEK/h

10 Indoor climate systems Default system Supply and exhaust ventilation with heat recovery, passive chilled beams and hydronic radiators Alternatives were Occupancy controlled ventilation Temperature controlled ventilation Without cooling Different duct system layout Airflow 0.35 l/(s m²) + 7 l/person

11 Proposed equations: Productivity cost q = 6.5 PI q e ( 21.6) 2 PD t t = room Relative increase q / (l/(s person)) Relative loss Indoor temperature/ C

12 Result without productivity cost CAV Life cycle cost / (SEK/m²) q / (l/(s m²)) DCV Life cycle cost / (SEK/m²) q / (l/(s m²)) Heat Chiller electricity Fan energy Space loss Repair Maintenance Chiller District heat exch. Air handling unit Adjustment Control Fire dampers Pipes, cold Chilled beams Pipes, heat Radiators Diffusers Silencers Exhaust duct comp. Exhaust ducts Supply duct comp. Supply ducts

13 Result with productivity cost related to airflow rate LCC / (SEK/m²) Initial cost / (SEK/m²) CAV - LCC DCV - LCC DCV - Init CAV - Init q/(l/(s m²)) 0

14 Result with productivity cost related to temperature LCC / (SEK/m²) CAV 200 SEK/h CAV 50 SEK/h CAV 0 SEK/h Temp span above and below 21.6 C/ C

15 Conclusions and discussion Old prices electronics and motors cheaper today than 2005 Demand controlled ventilation benefits easier How to get correct prices on components? A possible and useful influence on the producitivty from airflow rate or temperature has high impact Optimal airflow rates can be high Cooling is beneficial, Optimal airflow rate / (l/(s m²)) temperature control also 30 Initial cost not negligible With demand control, the CAV 15 airflow rate can be DCV 10 increased with constant 5 energy use Salary / (SEK/h)

16 School Indoor climate problems in schools seems not to be taken seriously Normally no cooling Higher people density than offices

17 Objectives LCC for heating, cooling and ventilation systems Theoretical school building 2 storeys 1200 m² Stockholm, Sweden Including productivity related cost based on airflow and temperature according to recent studies

18 LCC 40 year life span Net present value discount interest rate 1% electricity, 2% heat, 3% other Included costs Initial Energy Maintenance Repair Space loss Airflow related cost to represent health and productivity ProLive computer program for LCC

19 Ventilation systems Supply and exhaust ventilation with heat recovery Constant airflow with timer Constant airflow with chilled beams Demand controlled airflow 0.35 l/(s m²) + 7 l/(s person) Occupancy daytime 30%

20 Proposed equations: Productivity cost q = 6.5 PI q e ( 21.6) 2 PD t t = room Relative increase q / (l/(s person)) Relative loss Indoor temperature/ C

21 Result without productivity related cost Life cycle cost / (SEK/m²) Life cycle cost / (SEK/m²) Heat Fan energy Space loss Repair Left Constant airflow with timer Right Maintenance District heat exch. Air handling unit Adjustment Control Fire dampers Pipes, heat Demand controlled airflow X-axis Airflow per area Radiators Diffusers Silencers Exhaust duct comp. Exhaust ducts Supply duct comp. Supply ducts q / (l/(s m²)) q / (l/(s m²))

22 Result without productivity related cost Occupancy at daytime varied for normal airflow, 3.85 l/(s m²) higher airflow, 10 l/(s m²) constant airflow with timer versus demand controlled airflow Higher LCC at higher airflow Break point higher at higher airflow LCC / (SEK/m²) Daytime occupancy/% DCV 10 l/(s m²) CAV with timer 10 l/(s m²) DCV 3.85 l/(s m²) CAV with timer 3.85 l/(s m²)

23 Result with productivity related cost Value per hour of productivity due to airflow in legend Airflow per area on x-axis (LCC - LCC min ) / (SEK/m²) Initial cost / (SEK/m²) LCC 8 SEK/h LCC 20 SEK/h LCC 50 SEK/h Initial q/(l/(s m²)) 0

24 Result with productivity related cost Value per hour of productivity due to temperature in legend Constant airflow with timer Productivity value of 50 SEK/h LCC / (SEK/m²) Cooling is expensive No cooling Cooling Summer vacation not taken into account Los Angeles Paris Malmö Frösön Karasjok

25 Conclusions and discussion High optimal airflow rates limited by other criteria The method can be one tool to determine demands Rather old component price database Price of control and motorized diffusers have decreased Long term effects? How to value the work of pupils? Influences optimal levels and use of cooling

26 Dwellings LCC for heating and ventilation systems Theoretical detached house and multifamily apartment building Presentation focuses on detached house Including health related cost

27 LCC 40 year life span Net present value discount interest rate 1% electricity, 2% heat, 3% other Included costs Initial Energy Maintenance Repair Space loss Airflow related cost to represent health and productivity ProLive computer program for LCC

28 Ventilation systems Exhaust ventilation Exhaust in bathrooms and kitchen Supply from air valves at windows Exhaust ventilation with heat pump Heat pump recovers heat to tap water and heating Supply and exhaust system with heat recovery Airflow 0.35 l/(s m²) according to Swedish building code

29 Health cost Proposed equation: C health k2 = k1 e q Two examples, in SEK = 0.11 = 0.14 US$, over the life cycle Sick leave k1 = 774; k2 = 3.28 based on literature Asthma k1 = 838; k2 = 2.23 based on the Värmland study and a thesis regarding costs Life cycle health related cost / SEK Airflow / (l/(s m²)) Asthma Sick leave

30 Result without health related cost E SEH EHP Life cycle cost / SEK 1600 ycle cost / SEK ycle cost / SEK ,4 0,8 1,2 1, ,4 0,8 1,2 1,6 20 0,4 0,8 1,2 1,6 2 q / (l/(s m²)) q / (l/(s m²) q / (l/(s m²)) Heat Electrical energy Space loss Repair Maintenance District heat exch. Air handling unit Adjustment Pipes Radiators Diffusers Silencers Exhaust duct comp. Exhaust ducts Supply duct comp. Supply ducts

31 Result with health related cost E: exhaust ventilation S: supply and exhaust ventilation aa: asthma, sl: sick leave, co: both (LCC+health related cost) / SEK (LCC+health related cost) / SEK E,co E,aa E,sl E,no S,co S,aa S,sl S,no q / (l/(s m²)) q / (l/(s m²))

32 Conclusions and discussion Supply and exhaust ventilation has lower LCC at required airflow than exhuast Exhaust with heat pump lowest at required airflow Not at higher airflow rates Electricity price in future? Initial cost not negligible Health is an issue Optimal q / (l/(s m²) Reasonable airflow Should be combined with demand control Useful method? k 1 / [k 1 ] SEH E

33 Dwellings demand controlled ventilation

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37 Optimisation examples conclusions It is difficult to motivate low energy use if we value the benefit With higher energy prices, the optimal airflow rate decrease and temperature limits changes Initial cost increases with better indoor climate Indoor climate systems Right choice can decrease energy use at the same indoor climate Initial cost is usually higher at lower energy use Who pays what?

38 The building as a system Risks To decrease the CO 2 emissions (save the world) indoor climate is sacrificed The one paying the indoor climate system is stingy Energy use The building survives energi supply systems low use is more reliable than modern supply systems Windows increase cooling and heating Moisture design Moisture problems can result in increased energy use and bad indoor climate Does not need to increase energy use Air tight buildings is necessary

39 General conclusions A moisture safe building with good materials constructed for low energy use Low emissions Options for good ventilation and indoor temperature Demand controlled indoor climate Good when needed low energy use other times System choice Occupancy levels important as parameter Heat recovery Initial cost increases but not life cycle costs Need for better requirements and functions through research and system approach

40 Ongoing research Measurements in dwellings Household electricity Common electricity Presence of people (or pets) Domestic hot water Relative humidity Moisture supply Moisture production Ventilation airflow rate Carbon dioxide concentration Outdoor climate For about 15 multi family dwellings including about 300 apartments Spread over a few locations in Sweden Hourly During at least a year In central exhaust air of multi family dwellings

41 Ongoing research Measurements in other buildings A number of buildings of different kinds each 15 min during a year with the software in GOLD Temperature, vapour contents, specific fan power, airflow rates, occupancy, pressure, heat recovery Sweden, Norway and occasionally other locations

42 Ongoing research Other issues Life cycle cost simulations, energy calculations Softwares for system comparisons

43 Thanks for your attention!