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• Indoor climate (TC, IAQ, lighting, acoustics)• Energy performance and environmental performance
• In the design and in the assessment of performance of a existing building, ventilation rate is the most straightforward, however indirect measure of IAQ, together with low-polluting and dry building materials
• An example of the foot-print of indoor climate of a building according to EN 15251 (based on ventilation rate per person and very-low polluting materials)
• Ventilation (outdoor air flow) has to be adequate to remove and dilute the indoor generated pollutants and humidity, and provide acceptable level of contaminants in the indoor air
• Source control the first alternative to improve indoor air quality• Ventilation shall be energy efficient and arranged so that it does not
deteriorate indoor air quality and climate, and does not cause any harm to the occupants or to the building
• Ventilation rates should be based on the pollution loads and use of the building
• Many standards and a lot of scientific evidence related to ventilation
Evidence on SBS, PAQ, sick-leave, productivity (non-residential)
• Ventilation and performance of office work in relation to 6.5 L/s per person (Seppänen 2006)• Ventilation and short-time sick leaves in open-plan offices (Milton 2000)
Low ventilation increases humidity and symptoms in residences
Risk (odds ratio) of symptoms of asthma and allergy (wheezing, rhinitis, eczema) as a function of ventilation rates in single family houses (Bornehag et al. 2005)
1
2
3
0 0.17 0.26 0.38 0.62 h-1
Median air change in homes
1
2
3
0 0.17 0.26 0.38 0.62 h-1
Median air change in homes
0
5
10
15
20
=0.25 0.25- 0.50 >0.50Air change rate (h-1)
( )
>100mites per 0.1g mattress dust(P=0.024)
Prevalence of house dust mites in homes (Harving et al. 1993) Prevalence of house dust mites in homes (Harving et al. 1993)
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Main ventilation standards
• General standards (indoor climate), system standards and component standards
• CEN CR 1752:1998 Ventilation for buildings. Design criteria for the indoor environment
• EN 15251:2007 Criteria for the Indoor environment including thermal, indoor air quality, light and noise
• ASHRAE 62.1 (2007) Ventilation for acceptable indoor air quality• ASHRAE 62.2 (2007) Ventilation and acceptable indoor air quality in
low-rise residential buildings
• EN 13779:2007 Ventilation for non-residential buildings – Performance requirements for ventilation and room-conditioning systems
• (ISO 7730 & ASHRAE 55 – thermal comfort standards)
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System standards
• EN 13779:2007 Ventilation for non-residential buildings – Performance requirements for ventilation and room-conditioning systems
• EN 14788 Ventilation for buildings - Design and dimensioning of residential ventilation systems
• EN 12792 Ventilation for buildings - Symbols, terminology and graphical symbols
• EN 15241:2007 Ventilation for buildings - Calculation methods for energy losses due to ventilation and infiltration in commercial buildings
• EN 15242:2007 Ventilation for buildings - Calculation methods for the determination of air flow rates in buildings including infiltration
• EN 15243:2007 Ventilation for buildings — Calculation of room temperatures and of load and energy for buildings with room conditioning systems
• …
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Component standards (some examples)
• EN 13053 Ventilation for buildings — Air handling units — Rating and performance for units, components and sections
• EN 12237 Ventilation for buildings – Ductwork – Strength and leakage of circular metal sheet ducts
• EN 13141-7 Ventilation for buildings — Performance testing of components/products for residential ventilation — Part 7: Performance testing of a mechanical supply and exhaust ventilation units (including heat recovery) for mechanical ventilation systems intended for single family dwellings
• EN 13141-8 Ventilation for buildings - Performance testing of components/products for residential ventilation - Part 8: Performance testing of unducted mechanical supply and exhaust ventilation units [including heat recovery] for mechanical ventilation systems intended for a single room
qv the volume flow rate of supply air in m3/sG the net mass flow rate of emission to the room air in mg/sCin the allowed concentration in the room in mg/m3
Co the concentration in the supply air in mg/m3
ε
the ventilation efficiency, (ε = 1 for complete mixing to ε = 2 for ideal piston flow)
• The same type mass balance equation applies also for humidity balance of air. Removal of indoor generated humidity:
( )2 oin νν −
= hv
Gq
qv the volume flow rate of supply air in m3/sGh the indoor humidity generation in the room in g/sν
in the humidity by volume of the indoor air in the room in g/m3
ν
o the humidity by volume of the supply (outdoor) air in g/m3
qv the volume flow rate of supply air in m3/sGh the indoor humidity generation in the room in g/sνin the humidity by volume of the indoor air in the room in g/m3
νo the humidity by volume of the supply (outdoor) air in g/m3
From IAQ to ventilation rate (buildings designed for human occupancy)
• There do not exist a common standard index for the IAQ which will allow to use Eqs. (1)–(3) for determination of required ventilation rate
• Acceptable concentration of many various pollutants in indoor air is not known, especially for the mixtures of hundreds of the compounds found in the indoor air
• IAQ may be expressed as the required level of ventilation or carbon dioxide (CO2 ) concentration
• CO2 can be used as a surrogate of ventilation rates, but its use to measure ventilation is uncertain as its concentration in buildings seldom reaches steady state due to variations in occupancy, ventilation rates and outdoor air concentration
• Steady state values of carbon dioxide concentration can be calculated from CO2 generation of 0.00567 l/s per occupant in office buildings
• IAQ is influenced by emission from people and their activities (bio effluent, smoking), and from building, furnishing as well as from ventilation and air conditioning system itself (i.e. building components)
• The required ventilation is based on health and comfort criteria. In most cases the health criteria will also be met by the required ventilation for comfort. Health effects may be attributed to specific components of emission and if you reduce concentration of one source you also reduce concentration of others.
• Comfort is more related to the perceived air quality (odor, irritation). In this case different sources of emission may have an odor component that adds to the odor level.
• There is however no general agreement how different sources of emission should be added together.
• In the latest standards (EN 15251, ASHRAE 62.1 and 62.2) the criteria is expressed as addition of people (smoking, non-smoking) and building components. The total ventilation rate for a room:
Bptot qAqnq ⋅+⋅=
qtot total ventilation rate of the room, l/s n design value for the number of the persons in the room,-qp ventilation rate for occupancy per person, l/s, persA room floor area, m2
qB ventilation rate for emissions from building, l/s,m2
qtot total ventilation rate of the room, l/s n design value for the number of the persons in the room,-qp ventilation rate for occupancy per person, l/s, persA room floor area, m2
qB ventilation rate for emissions from building, l/s,m2
• Minimum ventilation rate 10–15 l/s per person, app. 1 l/s per m2 in office buildings with normal occupant density
• For better IAQ and productivity up to 2 l/s per m2 can be recommended for typical landscape and cellular offices
• This is supported by latest reviews by Seppänen and Fisk (2004) and Fisk and Seppänen (2007) that summarise the effect of ventilation in respect of health and productivity as follows:•
ventilation rates below 10 l/s per person are associated with a significantly higher prevalence of health or perceived air quality outcomes
•
increases in ventilation rates above 10 l/s per person, up to approximately 20 l/s per person, are associated with a significant decrease in the prevalence of SBS (sick building syndrome) symptoms or with improvements in perceived air quality and task performance and productivity.
•
relative to natural ventilation, air conditioning is often associated with a statistically significant increase in the prevalence of one or more SBS symptoms
•
For the residential buildings it is summarized that the ventilation rates below 0.5 ach (air change per hour) are a health risk in Nordic residential buildings (Wargocki et al. 2002 and Levin and Sundell 2007) concerning dwellings in a cold climate.
• l/s per person difficult to use in the design (occupant density is often not known)
• l/s per m2 values are common design specification
• Typical airflow rates:– 2 l/s per m2, 2.5 1/h in offices/commercial buildings– 3…4 l/s per m2, 3…4 1/h in classrooms– 0.35…0.5 l/s per m2, 0.5…0.7 1/h in homes
– If No of person known, 10 l/s per person (concert halls etc.)
– Still a lot of variation in national codes especially for homes
• The airflow pattern in a ventilated room depends on the selection and location of supply air devices whereas extract air devices have only small effect on it
• This is due to high momentum (air jet) of supply air compared to almost zero velocity near the suction point of extract air
Air distribution to the occupied zone:• serve supply air • avoid stagnant air• avoid draft
• Mixing ventilation is used in rooms with normal height (most homes and offices) and it can be provided with supply air diffusers, fan-coils or chilled beams etc. Complete mixing ⇒ the pollutants concentration diluted with ventilation is equal in the whole room .
• Especially in high rooms such as concert halls, auditoriums etc it is more efficient to bring fresh supply air directly to breathing zone. In displacement ventilation a stratified flow is created using a few degrees lower supply air temperature than room temperature.
• The opposite of the mixing flow pattern is the ideal piston flow in which the air flow is laminar and the room air is not mixed at all with the supply air
• This flow pattern with maximum possible ventilation effectiveness is used in special cases such as operating theatres and other super clean rooms
• CAV, VAV, AQCV• Air flows in the rooms can controlled according to the contaminant
loads or concentrations, term G in equation (1) • A room sensor can be one of the following: carbon dioxide, mixed-gas,
attendance, combined CO2 /mixed-gas, combined CO2 /temperature or combined CO2 /CO. At present mainly CO2 , temperature and attendance sensors are used for AQCV in normal spaces due to cost and unreliability of other types of sensors. CO-sensors are used in special cases such as large garages.
SENSOR • CO2 • ODOUR • VOC • PARTICLES
Ctrl
Ven
tila
tio
nra
te,q
v
CO -
concentration2
Min(~600 ppm)
Max(~1000 ppm)
Max
Min
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The Finnish IAQ Classification System Sisäilmastoluokitus 2008
Building and constructions
HVAC systems Classification of Building materials
Classification of ventilation
components
Instructions for design and construction (P)
Requirements for building products (M)
Target values for indoor air quality and climate (S)
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Aiming at high IAQ and TC
• The clients of building industry want better indoor environment that just a minimum requirements
• Significance of indoor climate for health, comfort and productivity has been well recognized
• The voluntary IAQ classification and labeling system is a tool for setting targets “above minimum”
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Target values (S)
• Three categories– S1 “individual”– S2 “comfortable”– S3 “satisfactory”
• Specified from client’s and engineer’s viewpoints• For ventilation rates, similar approach to EN 15251
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How it works?
IAQ and TC standard S1 or S2
HVAC-design values
Design specifications for moisture safety
Building site moisture control specifications
P1 ventilation cleanliness P1 construction cleanliness
M1 materials M1 ventilation products
End result complies with S1 or S2 targets after 6 months use
Design criteria
Construction criteria
Commissioning
Operation
Commissioning spec.
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Tekniset tavoitearvot
• Kriteerit tavoitearvoille– terveyden ja viihtyisyyden kannalta merkittäviä– rakennusprosessin osapuolten hallittavissa– todennettavissa luotettavasti kohtuukustannuksin
• Sisäilmastoluokitus 2008:ssa:– operatiivinen lämpötila– ilman liikenopeus– hiilidioksidipitoisuus– radonpitoisuus– valaistussuureet (viittaus standardiin)– akustisen suunnittelun suureet (viittaus standardiin)
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Osa tavoitearvoista on korvattu teknisillä vaatimuksilla
• TVOC, ammoniakki, formaldehydi, hajut käytettävä vähäpäästöisiämateriaaleja
• pienhiukaset käytettävä tuloilman suodatusta F8/F7 (vilkasliikenteisten katujen lähellä F9/F8)
• pöly ja lika rakennuksen ja ilmanvaihtokanavien pintojen puhtausvaatimukset
• mikrobit vaatimus veden- ja kosteudenhallinta-suunnitelmasta• tupakansavu sisätiloissa tupakointi kielletty
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Ulkolämpötila (24 h keskiarvo) [ ]°C
Operatiivinen lämpötila oleskeluvyöhykkeellä [ ]3029282726252423222120191817
°C
-15 -10 -5 0 5 10 15 20 25
Enimmäisarvo
Vähimmäisarvo
top
S3 3029282726252423222120191817
Lämpötilan tavoitearvot
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Ulkolämpötila (24 h keskiarvo) [ ]°C
Operatiivinen lämpötila oleskeluvyöhykkeellä [ ]3029282726252423222120191817
°C
-15 -10 -5 0 5 10 15 20 25
Enimmäisarvo
Vähimmäisarvo
top
Lämpötilan tulee pysyä alueella ± 1,0 .top °C 90 % käyttöajasta
S2 3029282726252423222120191817
Lämpötilan tavoitearvot
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Ulkolämpötila (24 h keskiarvo) [ ]°C
3029282726252423222120191817
-15 -10 -5 0 5 10 15 20 25
Enimmäisarvo
Vähimmäisarvo
top
Operatiivisen lämpötilan on oltava tila-/ huoneisto-kohtaisesti aseteltavissa välillä ± 1,5 .top °C
Lämpöti lan tulee pysyä alueella ± 0,5 .top °C 95 % käyttöajasta
S1Operatiivinen lämpötila oleskeluvyöhykkeellä [ ]3029282726252423222120191817
°C
Lämpötilan tavoitearvot
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Lämmitys- ja jäähdytysjärjestelmien suunnitteluarvoja
S1 S2 S3Jäähdytysjärjestelmän suunnitteluarvo °C 25 25 --Lämmitysjärjestelmän suunnitteluarvo °C 21,5 21,5 21,5Lämpötilan tilakohtainen säädettävyys, talvi °C 20…23 -- --Lämpötilan tilakohtainen säädettävyys, kesä°C 23…25 -- -Ilman nopeus, tilma =21 °C m/s <0,14 <0,17 <0,20Ilman nopeus, tilma =23 °C m/s <0,16 <0,20 <0,25Ilman nopeus, tilma =25 °C m/s <0,20 <0,25 <0,35Pystysuuntainen lämpötilaero (0,1/1,1 m) °C <2 <3 <4Lattian pintalämpötila, vähintään °C 19 19 17Lattian pintalämpötila, enintään (lattialämm.)°C 29 29 31Ilman suhteellinen kosteus, talvi % >25 -- --
• Oil concentration g/m2 of– ducts <0.05– terminal units and dampers <0.05– pressed components <0.3
• Mineral fibres (MMVF), f/cm3 <0.01
• Dust concentration, g/m2 <0.5
• Odour– acceptability of air quality passing
through the components >0.05
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Cleanliness criteria for ductworks
P1P1P1
P2 P2 Not accepted
Brush cleaned
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• Construction and installation works are critical regarding the cleanliness of the ventilation system
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M1 labeled products
• Today there are over 1200 classified products by over 110 producers.
• The largest product groups: – Plaster, rendering, putties,
fillers, flooring, paints and varnishes, building boards and mineral wool.
• See www.rts.fi for complete listing
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Experience from practice since 1995
• Over 1200 materials with M1-label -->reduces emissions by a factor of 10
• S1 targets have been met in building projects-->realistic• Category S2 well accepted as target level-->above minimum• Several new materials and products available -->helps product
Helsinki Univ. of Tech / HVAC-lab.Measured results: Tuomainen et al. 2003, Saarela et al. 2004
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Material emissions vs. ventilation rates
• Emissions dropped roughly by 10 times and general availability and use of M1 labelled materials makes it possible to use reduced airflow rates in buildings
• Significant equipment cost as well as energy savings potential (not yet used in practice)
• Reduction of air flow rates is addressed in new indoor climate standard EN 151251:2007:
where• qtot = total ventilation rate of the room, l/s • n = design value for number of the persons in the room,-• qp = ventilation rate for occupancy per person, l/s, pers• A= room floor area, m2
• qB = ventilation rate for emissions from building, l/s,m2
Bptot qAqnq ⋅+⋅=
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EN 15251 ventilation rates – airflow reduction by a factor of 2 for very-low polluted buildings
qp
qB
qtot
qB
qtot
Type of building or space
Cate-gory
Floor area m2/per-son
l/s,m2
for occupan
cy
l/s,m2
for very low-polluted building
l/s,m2
for non-low polluted building
I 10 1,0 0,5 1,5 2,0 3,0
II 10 0,7 0,3 1,0 1,4 2,1
Single office
III 10 0,4 0,2 0,6 0,8 1,2
I 15 0,7 0,5 1,2 2,0 2,7
II 15 0,5 0,3 0,8 1,4 1,9
Land-scaped office
III 15 0,3 0,2 0,5 0,8 1,1
I 2 5,0 0,5 5,5 2,0 7,0
II 2 3,5 0,3 3,8 1,4 4,9
Conference room
III 2 2,0 0,2 2,2 0,8 2,8
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Ilmanvaihdon mitoitus
• Ulkoilmavirrat standardin EN-15251:2007 mukaisesti. • Noudatettaessa Sisäilmastoluokituksen ohjeita voidaan rakennuksissa,
joissa tupakointi on kielletty, käyttää ulkoilmavirtojen mitoituksessa erittäin vähäpäästöisen rakennuksen mitoitusarvoja– S1-luokka: 0,5 l/s,lattia-m2 + 10 l/s, henkilö– S2-luokka: 0,5 l/s,lattia-m2 + 7 l/s, henkilö
• Huonelämpötilan hallinta tai varautuminen muunto-joustoon saattaa edellyttää suurempia ilmavirtoja.
• Erityisistä epäpuhtauslähteistä johtuvien päästöjen aiheuttama ilmanvaihdon tarve on otettava tapauskohtaisesti huomioon.
• Ilmavirtoja on voitava säätää tilojen käytön muuttuessa.• Normaalin käyttöajan ulkopuolella on rakennuksessa oltava
Basic question of IEQ: how to manage temperature and air distribution in classrooms with highly varying loads?
South classroom: 30 students + solar radiation = cooling need
North classroom, 15 students: heating need
No air conditioning, cost efficient ventilation system: • Constant ventilation or demand controlled ventilation • Supply air temperature compensation (cooling with outdoor air)
The same system should serve all classrooms
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Temperature compensation + flow control
• Supply air temperature and air flow rate control for cooling (with outdoor air + night ventilative cooling) – T and CO2 controlled ventilation (DCV)
Air-handling unit
Radiator andthermostatic valve
District heating supply
District heating return
District heating substation
Ven
tila
tio
nra
te,q
v
CO -
concentration2
Min(~600 ppm)
Max(~1000 ppm)
Max
Min
TS 22
23 TE19
16
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Room temperature and CO2 performance (Kurnitski et al. 2008)
• Room temperature data during one week in May (21-25.5.2007, mean outdoor temperature 13°C) from 63 classrooms. Data from the school time, from 8:00 to 14:00 on week-days.
18
20
22
24
26
28
0 0,2 0,4 0,6 0,8 1
Cumulative frequency, -
Roo
m te
mpe
ratu
re, °
C
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Temperature in August (warm period) 14-30.8.2007, just after summer holidays
20
22
24
26
28
0 0,2 0,4 0,6 0,8 1
Cumulative frequency, -
Indo
or te
mpe
ratu
re, °
C
y = 0,39x + 18,92R2 = 0,84
20
22
24
26
28
30
6 10 14 18 22 26Outdoor temperature, °C
Indo
or te
mpe
ratu
re, °
C
y = 0,23x + 20,96R2 = 0,79
20
22
24
26
28
30
6 10 14 18 22 26Outdoor temperature, °C
Indo
or te
mpe
ratu
re, °
C
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Temperature simulations
• 2 or 6 classroom simulations with part load vs. full load occupancy• Determining air flow rate and the control curve needed for the temperature
control (no cooling!)• CAV vs. DCV and heating season vs. summer performance
30 students South
20 studentsSouth
20 students South
20 studentsNorth
20 students North
30 students North
0
5
10
15
20
25
30
35
6:00
6:45
7:30
8:15
9:00
9:45
10:30
11:15
12:00
12:45
13:30
14:15
15:00
15:45
16:30
17:15
18:00
Time, hh:mm
No
of p
erso
ns
30 students/South20 students/North
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Results, summer
• Two ventilation rates, 6 L/s per person, 180 L/s per classroom in total or 10 L/s per person, 300 L/s per classroom in total.
• For both rates CAV system and DCV system with CO2 and temperature control was simulated. DCV system had two air flow steps, 100 % and 40% of total airflow.
Sum of degree hours in weekdays at 08:00-15:00, °Ch Heating season Summer periodVentilation system and classroom orientation Over 22°C Below 20°C Over 25°C Below 22°C
Criterion, °Ch 100 0 100 100CAVSouth classroom 300 L/s 181 0 200 118South classroom 300 L/s, with solar protection glasses 92 0 116 47North classroom 300 L/s, with low occupancy 0 56 11 212CAV + heating coil in supply duct for each classroomSouth classroom 300 L/s, with solar protection glasses 96 0 114 70North classroom 300 L/s, with low occupancy 0 0 11 106DCV 40-100%South classroom 120-300 L/s, with solar protection glasses 99 0 162 15North classroom 120-300 L/s, with low occupancy 0 0 7 105DCV 40-100% + night ventilative coolingSouth classroom 120-300 L/s, with solar protection glasses 99 0 83 31North classroom 120-300 L/s, with low occupancy 0 0 4 114
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Temperature controlEffective temperature control was possible by:
1. Supply air temperature going down to 14-15 °C with free cooling 2. Demand controlled ventilation (T and CO2 control to avoid excessive
cooling in North facade classrooms at part load)3. Ventilation rate of 10 L/s per person (5 L/s per m2)
Supply air temperaturecontrol curve
13
14
15
16
17
18
19
17 18 19 20 21 22 23 24
Exhaust air temperature °C
Supp
ly a
ir te
mpe
ratu
re °C
Supply air to classrooms in theheating seasonSupply air to classrooms in thesummer
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Which air distribution solutions are capable for 15°C supply air temperature and 5 L/s per m2
airflow rate without draft?
Wall diffusers – NO! Perforated duct – ?
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Duct diffusers – YES Ceiling diffusers – YES
E F
Duct diffusers – YES Displacement diffusers – ?
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Toimistoesimerkki (KesEn tutkimushanke TKK)
2.12.20 09
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Toimistoesimerkki
• Huoneistoala 6245 htm2, viisi kerrosta • Ikkunoiden pinta-ala 35 % julkisivun alasta ja 19 % huoneistoalasta
• Vaipan lisälämmöneristäminen ei taloudellisesti kannattavaa. Ei sen takia, että rakentamiskustannukset olisivat niin suuria, mutta energiansäästö hyvin vähäinen. (Siis pientalotason lämmöneristys ei ole järkevä toimistorakennuksessa.)
• Tarpeenmukainen iv (VAV) ei vielä taloudellisesti kannattavaa • Erillispoistojen LTO kannattava jo nyt• Valaistuksen ohjaus kannattava jo nyt• Tulokset eivät ole herkkiä energian hinnan muutokselle
• Vaipan lisälämmöneristäminen ei taloudellisesti kannattavaa. Ei sen takia, että rakentamiskustannukset olisivat niin suuria, mutta energiansäästö hyvin vähäinen. (Siis pientalotason lämmöneristys ei ole järkevä toimistorakennuksessa.)
• Tarpeenmukainen iv (VAV) ei vielä taloudellisesti kannattavaa • Erillispoistojen LTO kannattava jo nyt• Valaistuksen ohjaus kannattava jo nyt• Tulokset eivät ole herkkiä energian hinnan muutokselle