MONITORED RESULTS FROM THE YELLOW HOUSE

Olaf B. Jørgensen and Lars T. NielsenEsbensen Consulting Engineers, Vesterbrogade 124 B, 1620 Copenhagen V, Denmark, Phone Number: +45 3326 7300,

Fax Number: +45 3326 7301, E-mail address: o.b.joergensen@esbensen.dk, l.t.nielsen@esbensen.dk,

Abstract – This paper describes the results of the monitoring program for The Yellow House, whichconsists of a four-storey high building with eight apartments. The monitoring started after the completionof the renovation in December 1996 and will continue until July 2000. Not all components have beenmeasured during the whole period. The monitoring contains data for each apartment for space heating,electricity, cold water, hot water and gas. Also long-term measurements of the relative air humidity androom temperatures in two apartments have been made together with short-term measurements of daylightlevels. For The Yellow House data has been registered for the PV-panels and solar collectors and also theclimatic data have been measured. A questionnaire has been evaluated and a user survey will be carriedout during summer 2000.

1. INTRODUCTION

Due to degradation of the building envelope, a renovationand an urban renewal of old multi storey housings indense urban areas throughout Europe is very urgent. Theaim of this project has been to use solar energy to reducethe overall energy consumption for space heating,ventilation, hot water and electricity by up to 70%.

The paper summarises a significant Danish solar energybased renovation of a multi-storey building with 8apartments. Various types of solar energy utilisation areexploited to achieve a major reduction of the energyconsumption. The project has served as the Danishdemonstration project in the IEA SH&CP Task 20: “SolarEnergy in Building Renovation”.

The results and experiences from the design andconstruction phase have previously been reported atEuropean solar conferences (EuroSun 96 and NorthSun97). Monitoring and evaluation is now being completedand this paper focuses on reporting the monitored resultsand the conclusions derived from the monitoring.

2. OBJECTIVES

The design team has carried out comprehensiveparameter studies and a promising design has beendeveloped. Valuable design review comments have beenreceived from the partners of the IEA Task 20 experts.Monitoring has been carried out since 1997 and willcontinue until the end of July 2000. For all apartments,hourly values with respect to space heating andventilation, use of cold and hot water, electricity use anduse of gas are monitored. Furthermore, indoor airtemperatures, relative air humidities and solar gains aremonitored in detail. Short term monitoring of daylightlevels, has also been carried out. Furthermore, theperformance of the solar collectors and the PV-panels hasbeen carefully monitored. Also comprehensive

monitoring of the outdoor climate has been carried out inorder to define the solar fraction of the implemented solartechniques. Finally, tenants satisfaction will be evaluatedbased on a user questionnaire.

3. DESCRIPTION OF THE YELLOW HOUSE

3.1 Characteristics for The Yellow HouseThe Yellow House is located in the centre of Aalborg,Denmark. It was built in 1900, is four stories high andconsists of 8 apartments. The orientation of the buildingfacades is South-North with the South facade facing abackyard and the North facade facing to a street. East-West walls are connected to the neighbouring buildings.

Figure 3.1: South facade of The Yellow House.

Persons inapartm.

[-]

Gross areaAfter[m²]

Net areaAfter[m²]

Net areaBefore[m²]

GF Left 2 72.0 67.0 54.1GF Right 2 62.0 57.0 48.11st Left 2 76.0 70.3 54.11st Right 2 63.0 57.0 48.12nd Left 1 76.0 70.3 54.12nd Right 2 68.0 62.0 48.13rd Left 1 63.0 58.5 44.23rd Right 1 65.0 60.1 40.3Total 13 545.0 502.2 391.1Table 3.1: The number of people living in the eightapartments, the gross area and net area after renovationand the net area before renovation.

Figure 3.2: Location of Aalborg (56.9 N, 9.9 E)

In 1996 the house was renovated to modern as well asfuture standards. Many new techniques have been usedtogether with known ones. This includes the use of highlyinsulated low-e double glazing with integrated lamellas.The window areas are increased significantly, providingbetter daylight conditions. The use of advanced glazedbalconies has increased the apartments gross area,depending of location of apartment. The ventilationsystem is demand controlled (moisture regulated) toimprove the indoor air quality and to reduce themechanical ventilation rate. Domestic hot water issupplied from roof integrated solar collectors. Parts of theexterior walls that are not facing North have beeninsulated with opaque insulation. The solar walls are usedfor preheating the ventilation air. The PV-panel is gridconnected and integrated in the solar wall. Furthermore,the savings from the solar techniques have beensupplemented with energy saving measures and watersaving devices.

3.2 Glazed facadesThe use of glazed facades has several advantagesdepending on type of construction and therefore seven

different types of glazed facades have been evaluated andtwo types have been selected for the renovation. One isan integration of the balcony, which enlarge the size ofthe whole apartment. The second is a glazed balcony,which gives a lower energy loss due to a higher“ambient” temperature and reduced infiltration.

3.3 Daylight ConditionsThe large window areas will result in a high level ofdaylight inside the apartments and together with the newglazed facade this will result in a more even daylightdistribution than before the renovation. No problems withglare are expected, due to the integrated lamellas betweenthe glazing. The visual comfort and the quality of livingare improved significantly with this design.

3.4 Windows with integrated Venetian blindsLow-e double glazing with integrated Venetian blinds areexpected to reduce the number of hours with indoor airtemperatures above 24°C from 4,800 to 500 hours. Toensure this it is important that the solar gain controlsystems are simple and easy to use and that they arerobust and do not require a lot of maintenance.

3.5 Roof Integrated Solar CollectorThe area on which the solar collectors can be placed onthe roof of The Yellow House is smaller than thetechnical most attractive for a building of this type. Thismeans that the roof integrated solar collectors will notcover the heating of the domestic hot water to the sameextend as normally intended. However, the sizing of thecollector area also depends on how much of the roof areathat can actually be used as collector area. Thus, in TheYellow House the optimum size of the collector area was18 m² also taking the architectural aspect intoconsideration. Such a collector is expected to coverapproximately 30% of the energy demand for productionof domestic hot water.

3.6 Integrated PV-panelsThe PV-panels are placed only on the south facade. Someof the PV-panels are tilted 30° (vertical), but most of theventilated PV-panels are integrated in the vertical solarwalls. The integration in the solar walls lowers theefficiency because of the extra layer of glass in front ofthe PV-panel and because of less direct solar incidencecompared to the tilted PV-panels. This has been madepartly for architectural reasons, partly for technicalreasons (PV panels as absorbers in the ventilation solarwalls) and has given the facade a unique design. The PV-panels size of 22.3 m² was given as the space inside thesolar walls plus the optimised size of the tilted PV-panels.Power from the PV-panels is mainly used in the house.However, the electricity is sold to the grid when thedemand in the house is lower than the power produced.

Figure 3.3: Detailed picture of PV-panels integrated insolar walls.

3.7 Demand Controlled VentilationIn The Yellow House a demand controlled moistureregulated ventilation system combined with ventilatedsolar walls for preheating ventilation air is used. Thisimproves the indoor air quality much faster than aventilation system with heat recovery as the polluted airis removed immediately. The running costs are reducedsignificantly as the ventilation rate and thus the use ofelectricity is decreased when the moisture content is low.

4. EXPECTATIONS

The many new techniques used in The Yellow House areexpected to ensure a very low energy demand comparedto conventional renovated buildings.

The use of advanced glazed balconies, extra insulation,high performance windows, etc. was estimated to reducethe energy consumption for The Yellow Housesignificantly. The expected and calculated energy savingsfrom the design phase are:

• Savings of 60% for space heating and ventilation• Savings of 50% for heating domestic hot water with

the use of solar collectors combined with new watersaving devices. The solar collectors alone shouldsupply 30%.

• Savings of 65% for the use of electricity forequipment and indoor lighting are expected due tonew low energy appliances.

• Daylight factors of more than 2% at a distance of2 meters from the south facade.

• Improved indoor climate. Not more than 500 hourswith temperatures exceeding 24° in the glazedbalconies.

Unfortunately, it was not possible to use the originaldesign of The Yellow House, as another house with lesssolar incidence had to be used. For this reasons the netenergy consumption is supposed to be a bit higher than

estimated above. The first house considered was not usedso instead the present house is used, but the solar gainscan not be as high due to shadows from neighbouringbuildings. For different reasons a less efficient energydesign have been selected for the advanced glazedbalconies and the solar walls, compared to the originaldesign proposal.

5. MONITORING PROCEDURE AND STATUS

The monitoring program in The Yellow House is quitecomplex, because of the many parameters registered. Thefollowing sections describe the different kinds ofmeasurements made in the monitoring period. Detailedmeasurements of the indoor climate and the daylight levelhave been carried out in two selected apartments (Groundfloor right and 1st floor left). Section 5.6 describes theproblems in the monitoring phase and how they couldhave been prevented.

5.1 Measurements of use of resources in the apartmentsThe SYNERGYR system uses a computer to savehourly values of the energy use for space heating andelectricity, cold water, hot water and gas. The data hasthen been collected through a modem in order to beanalyzed. Minor problems have occured in themonitoring phase, see section 5.6.

1) Combined control valve/energy meter2) Analogue room apparatus3) Programable room apparatus4) Universal adaptor5) Central Unit (PC)6) Read-out card7) Heat regulator

Figure 5.1: Diagram showing the SYNERGYR system.

The SYNERGYR is a system that allows the tenants toget information about their energy consumption for allthe above mentioned elements. They can do that by eitherusing their text-TV or simply by watching a coloreddisplay showing their consumption over the last periodcompared to a reference level.

Figure 5.2: Colored display that allows the tenants to getinformation about their energy consumption.

5.2 Measurements of rel. humidity and temp. insideSmall relative humidity and temperature loggers wereplaced in two selected apartments. They were placed instrategic places in the glazed balconies and in the livingroom next to the glazed balconies.

The monitoring period was to finish by the end of April2000, but due to the loss of some data in Summer 1999,the monitoring period will continue until August 2000.Otherwise, the measurements have been made every 15minutes since March 1999.

Figure 5.3: Picture of Tinytags loggers. Temperature(left), temperature/humidity (middle), matchbox (right).

5.3 Measurements of daylight levelIn august 1999 the daylight level was monitored over oneweek in two different apartments. It was not possible tomeasure the horizontal daylighting level, but only thevertical level towards the window. As people were livingin the apartment, the equipment could not be placed in the

same distance from the windows and the results cantherefore not be directly compared.

Figure 5.4: Pictures of the equipment used to measure thedaylight level both inside and outside.

5.4 Measurements of outdoor climateRight next to The Yellow House a weather station hasbeen set up. Ambient temperature, relative humidity,wind speed, wind direction, air pressure and globalradiation on horizontal has been measured every 10minutes since May 1999.

Figure 5.5: View from the weather station.

5.5 QuestionnairesA questionnaire has not yet been given to the tenants andhas therefore not yet been evaluated. They will bedistributed in May 2000 and the results will be presentedat the EuroSun 2000 conference.

5.6 Lost measurements and general problemsGood planning can avoid many problems in a monitoringprocess, but it is almost impossible to foresee allproblems that can occur.

This project is no different from others on this matter.The most critical failure happened when the smallTinytag loggers were programmed to “Stop when full”instead of “Overwrite old data”. This meant that soonafter the first successful readings the logging stopped. Asthe loggers can log for almost 3 months all data fortemperature and humidity inside the apartments aremissing for the summer of 1999. These parameters arevery important and therefore it has been decided toextend the monitoring period over the summer 2000.

The loggers in the apartments are set to measure every 15minutes and the weather station is logging every 10minutes. This means that only two measurements aretaken at the same time every hour. Therefore, always setthe same measuring interval for individual loggers. In thismonitoring program a logging interval of one hour wouldhave been sufficient.

Data are missing in February 2000 from theSYNERGYR system due to problems with thedownload. This happened as the neighbouring buildingcut the wires to the computer when renovating thebuilding. More often downloads of files could havelimited the period of data missing.

Even though the tenants are very friendly, there is a limitfor how much inconvenience they will except and thismakes it difficult to check the equipment frequently.

Also the distance to location of measuring is important. Along distance makes it very time consuming to come andcheck the equipment.

So the following sentence is important to remember whendealing with monitoring: “In theory there is no differencebetween theory and practice. In practice there is”.

6. RESULTS

There are thousands of data in this project and it wouldvery difficult to present them all clearly, so the mainresults are presented below.

6.1 Measurements of use of resources in the apartmentsSince the beginning of 1997 data from theSYNERGYR system have been collected, but not until1998 the data are stable and continuous. The followinggraphs show the annual consumption of space heating,electricity, cold water, hot water and gas for eachapartment. Wherever possible the consumption beforerenovation is shown on the graph too.

6.1.1 Space heatingAnnual heating consumption in The Yellow House

0.0

10.0

20.0

30.0

40.0

50.0

60.0

70.0

80.0

90.0

100.0

110.0

120.0

GF-Left GF-Right 1st-Left 1st-Right 2nd-Left 2nd-Right 3rd-Left 3rd-Right

He

atin

g c

on

sum

ptio

n [

kWh

/m²

pe

r ye

ar]

Before ren.(calculated)

After ren.(calculated)

Measuredin 1997

Measuredin 1998

Measuredin 1999

Figure 6.1: Annual energy consumption for spaceheating.

The red and green post shows the calculated consumptionfor space heating before and after the renovation. Theyellow, blue and pink posts show the measuredconsumption from 1997-1999. The first noticeable is thevariation in heating consumption for the tenants. Someapartments use more than twice as much heat as others inthe same year. Some apartments use more heat thanexpected after renovation, some use less. The totalcalculated energy consumption is 93 kWh/m² per yearbefore renovation and 54 kWh/m² per year afterrenovation. From table 6.1 it can be seen that the savedenergy for space heating is about 30-40%, but also thatthe tenants use 0-20% more energy than expected fromthe calculation of the energy demand after the renovation.

Variation in %Measured space heating Year total[kWh/m²a] before after

1997 65 70 1211998 53 58 991999 63 68 116Before renovation 93 - -After renovation 54 - -Table 6.1: Energy savings for space heating compared tothe calculation of the energy demand before renovation.

6.1.2 ElectricityAnnual electricity consumption in The Yellow House

0

5

10

15

20

25

30

35

40

45

50

GF-Left GF-Right 1st-Left 1st-Right 2nd-Left 2nd-Right 3rd-Left 3rd-Right

Ele

ctri

city

co

nsu

mp

tion

[k

Wh

/m²

pe

r ye

ar] Measured

in 1997

Measuredin 1998

Measuredin 1999

Estimate of average annual consumption before renovation

Figure 6.2: Annual demand of electricity.

The consumption of electricity varies between theapartments, but in general the consumption is around10-20 kWh/m² pr year for all apartments, except 2nd leftwhich has a significant large consumption of electricity.

The consumption before renovation was for the wholebuilding 23.5 kWh/m² per year. The total consumptionfor the whole building from 1997-1999 can be seen fromthe table below. Here it is also possible to see that the useof electricity has been reduced by 10-30%. If the tenantsliving in 2nd left had used a normal amount of electricitythe reduction would have been higher (~15-40%).

Measured electricity Year total[kWh/m²a]

Percent[%]

1997 21.5 911998 18.4 781999 16.2 69Before renovation 23.5 100Table 6.2: Reduced use of electricity compared withbefore renovation.

6.1.3 Cold waterAnnual cold water consumption in The Yellow House

0

5000

10000

15000

20000

25000

30000

35000

40000

45000

GF-Left GF-Right 1st-Left 1st-Right 2nd-Left 2nd-Right 3rd-Left 3rd-Right

Co

ld w

ate

r co

nsu

mp

tion

[li

tre

s/p

ers

on

pe

r ye

ar]

Measuredin 1997

Measuredin 1998

Measuredin 1999

Figure 6.3: Annual consumption of cold water.

The consumption of cold water varies both between thetenants and through the years. A clear falling or raisingtendency can not be concluded.

6.1.4 Hot waterAnnual hot water consumption in The Yellow House

0

10000

20000

30000

40000

50000

60000

GF-Left GF-Right 1st-Left 1st-Right 2nd-Left 2nd-Right 3rd-Left 3rd-Right

Ho

t w

ate

r co

nsu

mp

tion

[li

tre

s/p

ers

on

pe

r ye

ar]

Measuredin 1997

Measuredin 1998

Measuredin 1999

Estimate of average annual consumption before renovation

Figure 6.4: Annual consumption of hot water.

It differs a lot on how much hot water the differentapartment use. This might have to do with the number ofpeople living in the apartment and to bathing behaviour.In general, the level has fallen for most of the apartmentssince the renovation. From the table below the annualconsumption per person for The Yellow House issummed up and the savings are around 10-25%.

Measured DHW Year total[litres/pers*a]

Percent[%]

1997 22,262 901998 19,787 801999 18,130 73Before renovation 24,692 100Table 6.3: Saved energy for domestic hot water perperson compared with before renovation.

6.1.5 GasAnnual gas consumption in The Yellow House

0

5

10

15

20

25

GF-Left GF-Right 1st-Left 1st-Right 2nd-Left 2nd-Right 3rd-Left 3rd-Right

Gas

consu

mptio

n [kW

h/m

² per

pers

on p

er

year] Measured

in 1997

Measuredin 1998

Measuredin 1999

Estimate of average annual consumption before renovation

Figure 6.5: Annual consumption of gas used for cooking.

For most of the apartments the consumption of gas forcooking has fallen significantly after the renovation.Again one apartment has a noticeable higher consumptionthan the others. In the table below it can be seen that thereduction is around 20-25%.

Measured Gas Year total[kWh/m²a]

Percent[%]

1997 8.2 821998 7.5 751999 7.5 76Before renovation 9.9 100Table 6.4: Annual gas consumption for cookingcompared with before renovation.

6.2 Measurements of rel. humidity and temp. insideMeasurements of moist and temperature in 'The Yellow House' (1st-L)

-20

-10

0

10

20

30

40

50

60

70

80

90

100

mar1999

apr1999

maj1999

jun1999

jul1999

aug1999

sep1999

okt1999

nov1999

dec1999

jan2000

Te

mp

era

ture

[°C

], R

el.

Hu

mid

ity [

%]

1st left : RH% (balcony) 1st left : Temperature (balcony)

1st left : RH% (livingroom) 1st left : Temperature (livingroom)

<Outdoor humidity> <Outdoor temperature>

Figure 6.6: Relative humidity and temperature inapartment 1st left.

The typical relative humidity level indoors is low in thewintertime, raising during springtime, peaking in summerand finally falling in the autumn. The same tendency isvalid for the relative humidity in the living room and inthe glazed balcony, even though data for the summer ismissing. The humidity outside has the opposite tendency,low levels during summer and high levels at wintertime.

The relative humidity and temperature measured in theapartment Ground floor right, show the same tendency asfor the apartment 1st left and is therefore not shown here.Instead, the tables below show the average relativehumidity for the four seasons. The indoor levels duringwinter are fairly low for both apartments, which mightlead to problems with static electricity, and dry throats.For the summer period the levels are fine.

Rel. humidity 1st left livingroom

1st leftbalcony

Outdoorhumidity

Spring 1999 42% 50% 74%Summer 1999 55% 58% 78%Autumn 1999 56% 69% 88%Winter 1999 41% 70% 93%Table 6.5: Seasonal average relative humidity, 1st left

Rel. humidity GF rightliving room

GF-rightbalcony

Outdoorhumidity

Spring 1999 34% - 74%Summer 1999 50% - 78%Autumn 1999 44% - 88%Winter 1999 26% - 93%Table 6.6: Seasonal average relative humidity, groundfloor right.

Unfortunately, most of the temperatures are missing forthe summer period. However, the temperatures in thebalcony in apartment 1st left have been measured duringsummer. From this, it can be seen that the temperature inthe balcony in 1999 only a couple of times increases 30°

and exceeds 24° in only 305 hours. The temperature inthe living room seems very steady, which also can beseen from the tables below showing the averagetemperatures during the four seasons in both apartments.It is noticeable that the ground floor right apartment hasvery high temperatures during winter, which is not thecase for the apartment 1st left. The energy consumptionalso shows that this apartment in 1999 used more thantwice as much energy for space heating as the other one.

Temperature 1st left livingroom

1st leftbalcony

Outdoortemperature

Spring 1999 19.8° 14.8° 10.8°Summer 1999 20.2° 20.9° 16.3°Autumn 1999 19.0° 17.7° 10.4°Winter 1999 17.2° - 2.9°Table 6.7: Seasonal average temperature, 1st left

Temperature GF rightliving room

GF-rightbalcony

Outdoortemperature

Spring 1999 21.9° 15.2° 10.8°Summer 1999 21.9° 20.5° 16.3°Autumn 1999 22.4° 15.0° 10.4°Winter 1999 23.7° 8.1° 2.9°Table 6.8: Seasonal avg. temperature, ground floor right

6.3 Measurements of the daylight levelOne day a week in each apartment has been chosen fromthe monitoring period. The vertical daylight level andvertical solar radiation level is shown below.

Solar radiation and daylight conditions in GF Right (23-08-1999)

1

10

100

1000

10000

100000

1000000

00:0

0

01:0

0

02:0

0

03:0

0

04:0

0

05:0

0

06:0

0

07:0

0

08:0

0

09:0

0

10:0

0

11:0

0

12:0

0

13:0

0

14:0

0

15:0

0

16:0

0

17:0

0

18:0

0

19:0

0

20:0

0

21:0

0

22:0

0

23:0

0

00:0

0

Sola

r ra

dia

tion [W

/m²]

, Dagsl

ys [l

ux]

Daylight outside Solar radiation outsideDaylight inside Solar radiation inside

Figure 6.7: Daylight conditions in apartment GF right.Note the use of logarithmic scale.

Solar radiation and daylight conditions in 1st Left (28-08-1999)

1

10

100

1000

10000

100000

1000000

00:0

0

01:0

0

02:0

0

03:0

0

04:0

0

05:0

0

06:0

0

07:0

0

08:0

0

09:0

0

10:0

0

11:0

0

12:0

0

13:0

0

14:0

0

15:0

0

16:0

0

17:0

0

18:0

0

19:0

0

20:0

0

21:0

0

22:0

0

23:0

0

00:0

0

Sola

r ra

dia

tion [W

/m²]

, Dagsl

ys [l

ux]

Daylight outside Solar radiation outsideDaylight inside Solar radiation inside

Figure 6.8: Daylight conditions in apartment 1st left. Notethe use of logarithmic scale.

The two figures above show the solar radiation and thedaylight conditions both inside and outside. As themeasurements are taken vertically, the standard daylightfactor can not be calculated and therefore it is impossibleto compare the measured result with the expected 2% in adistance of 2 meters from the south facade. Instead, anadjusted vertical daylight factor is calculated and theaverage values (from the hours 10:00 to 18:00) can beseen from the table below.

Distanceto

window

Verticaldaylightfactor

Verticalsolar radiation

factorGF-right(23-08-1999)

2,5 m 3.6% 2.6%

1st-left(28-08-1999)

2,0 m 0.8% 4.8%

Table 6.9: Vertically daylight and solar radiation factors.

The reason why the vertical daylight factor is lower at 1st

left than GF right is because Venetian blinds are used at1st left and are not used at GF right. The Venetian blindsreduce the levels dramatically, but still the level of lightseemed sufficient at 1st left.

The vertical daylight factor and the vertical solarradiation factor are not proportional between the twoapartments. The weather influences a lot on this. Anovercast sky can change the proportionality a lot. Alsothe placement of the sensor influences. As it could beseen from the picture 5.4, the indoor sensor is placedclosely up against the wall, because of access possibilitiesfor the tenants. Therefore the results should only be takenas a pointer for the daylight conditions inside theapartments.

6.4 Measurements of outdoor climateClimatic data near TYH - Temp, Rel. humidity, Windspeed

-10

0

10

20

30

40

50

60

70

80

90

100

ma

j - 1

99

9

jun

- 1

99

9

jul -

19

99

au

g -

19

99

sep

- 1

99

9

okt

- 1

99

9

no

v -

19

99

de

c -

19

99

jan

- 2

00

0

Un

its [

°C,

%,

m/s

]

Humidity

Temperature

Wind speed

Figure 6.9: Climatic data of relative humidity,temperature and wind speed.

Climatic data near TYH - Air pressure, Solar radiation

0

100

200

300

400

500

600

700

800

900

1000

1100

1200

ma

j - 1

99

9

jun

- 1

99

9

jul -

1999

au

g -

19

99

sep -

1999

okt

- 1

99

9

nov

- 1999

de

c -

19

99

jan

- 2

00

0

Uni

ts [h

Pa,

W/m

²]

Air pressureTotal horizontal radiation

Figure 6.10: Climatic data of air pressure and solarradiation.

The graphs above show hourly values of climatic datathat have been measured every 10 minutes. Thetemperature logger stopped measuring medio November1999, but it will be possible to get hourly values by theend of the measuring period from another location nearbyThe Yellow House. From the climatic data it is possibleto create an input file for thermal simulation programs.These simulations will be compared with the monitoredresults. Parts of this comparison will be presented at theEuroSun 2000 conference.

6.5 PV-panelsProduction from PV-panels

0

1

2

3

4

5

6

Jan Feb Mar Apr Maj Jun Jul Aug Sep Okt Nov Dec

Ele

ctrici

ty p

rod

uct

ion

[kW

h/m

² p

er

mo

nth

]

Production 1998

Production 1999

Production 2000

Figure 6.11: Production of electricity from the PV-panels.

The PV-panels has worked without any problems since itwas installed in April 1997. The reason why theproduction is low in June and July is that the solar angleis very high and therefore the glass covering the verticalPV-panels will reflect some of the solar gain. Around20-30% of the produced electricity is sold to the grid forthe summer months and less for the winter months. Thetable below shows the annual production and sale to thegrid.

Units 1997 1998 1999Production kWh 531.4 663.9 734.1Production kWh/m² 23.8 29.8 32.9Sale to grid kWh 140.2 170.5 210.0Sale/Prod. - 26 26 29Sun hours Shr 1984 2025 1798Table 6.10: Production from PV-panels and sale to grid.

The production of the PV-panels is approx. 30 kWh/m²per year. This is a bit lower than expected. Duringsummer 2000 this possible malfunction will beinvestigated.

6.6 Solar collectorsThere have been many problems with the collectors untilDecember 1998, but since January 1999 the system hasoperated in a satisfying way and have produced 35.6% ofthe energy used for domestic hot water, which is morethan the expected 30% estimated in the calculations. Thetable below shows the production from 1997-1999.

Units 1997 1998 1999Production kWh 4279.0 1544.9 6053.4Production kWh/m² 235.1 84.9 332.6Sale to grid kWh 220.1 238.8 96.1Sale/Prod. - 19.4 6.5 63.0Sun hours Shr 1984 2025 1798Table 6.11: Production from solar collectors andelectricity to run the circulation pump. Heat factor gainedper used electricity unit.

The total production from the solar collectors with a totalarea of 18.2m² was in 1999 more than 330 kWh/m². Thegained heat per used kilowatt-hour electricity was 63kWh, which is considered very satisfying.

6.7 QuestionnairesNo results yet. Will be presented at EuroSun 2000conference.

7. CONCLUSION

Statistically, it is not enough to evaluate the energyconsumption for only eight apartments. The individual,differences are too big and can result in a wrongconclusion. The tenants in The Yellow House have very

individual energy demands. Tenants using much energyfor space heating might not use a lot of hot water orelectricity. There is no parallel between the demands forcertain kinds of energy. But the results can indicate if theexpected energy savings have been accomplished.

The energy demands for space heating were expected tobe reduced by 60%. The result is a reduction around30-40% of the level before renovation. However thechange of construction and location of The Yellow Houseresulting in less implementation of solar elements andsmaller solar gains than for the design case are some ofthe reasons for this difference.

For domestic hot water energy savings of 50% wereexpected. The result is a reduction around 10-25%. Themain reason for this smaller reduction is that the tenantsuse much more hot water than normal for referencebuildings.

The solar collectors should supply 30% of the energydemand for heating domestic hot water. Due to problems,the first fully effective year was 1999 and here the solarcollectors supplied 35.6% of the energy demand forheating domestic hot water. This is very satisfying.

For the electricity the expected reduction was 65%. Theoverall result is between 10-30%. Here the individualdemands are significant. Some tenants saves more than65%, some uses 75% more than before renovation.

The production of the PV-panels is approx. 30 kWh/m²,corresponding to an efficiency of ~ 4.5%. This is fairlylow compared to an expected efficiency around 10%.This possible failure will be investigated during summer2000.

The daylight factors could not be measured according tothe standards and therefore it is not possible to check ifthe promised daylight factors were perceived. Also theright type of sky was not present for this kind ofmeasurement. In spite of this the vertically daylight factormeasured showed values that indicated good daylightconditions. This is also the reaction that has beenobserved when talking to the client and the users.

The indoor climate has been improved significantly. Nodraught is coming from the windows and the hours in1999 with temperatures above 24° were 305, which wasbetter than the 500 hours that had been calculated. Therelative humidity seems low especially during winter, butplants could improve the situation. During summertimethe relative humidity levels are very fine.

In general the energy savings are lower than expected,but often the reductions are even bigger than expected, sothe overall result is considered very satisfying.

On top of this, many lessons have been learned from theproject, both good and bad, and valuable experiences hasalready been taken into new projects. This is relevant forthe design team as well as for the client.

Figur 7.1: Picture of the south facade of The YellowHouse.

8. ACKNOWLEDGEMENT

The Danish Ministry of Housing is funding this projecttogether with The Municipality of Aalborg and theDanish Ministry of Energy.

SBS Urban Renewal has represented the client and hasparticipated actively in the design phase as well as in theevaluation phase.

9. REFERENCES

[1] Jensen, J.M., Lund, H. (1995) Design ReferenceYear, DRY – et ny dansk referenceår. LFVMeddelelse Nr. 281, Institut for Bygninger ogEnergi, English summary.

[2] Hansen, H.E. et al. (1997) Varme- og klimateknik,Danvak, 2nd edition. (in Danish)

[3] Blegvad, J, Esbensen, (1995) Det Gule Hus,Byøkologiprojekt i Aalborg, Udviklingsrapport (inDanish).

[4] Jørgensen O. B. (1996) Integration of solar energyin future renovation of multi storey housing – TheYellow House. EuroSun 96, Freiburg, Germany.

[5] Jørgensen O. B. (1997) The Yellow House – Aninnovative solar renovation of multi storey housing.Proceedings of the Seventh InternationalConference, Espoo-Otaniemi, Findland, pp. 364-371.

[6] Voss, K. (2000) Solar Renovation DemonstrationProjects: Results and Experience. IEA Task 20:Solar Energy In Building Renovation.

[7] Nielsen, J.V., Gregersen, G.S., Det Gule Hus(forsøgsrapport) (1999) By-og Boligministeriet,Aalborg kommune, SBS Byfornyelse. (in Danish)

[8] Kjølby, H., Jønson, F. (1999) Plant et hus,årsrapport Nr. 2 1998, Energicentret. (in Danish)

[9] Kjølby, H., Jønson, F. (2000) Plant et hus,årsrapport Nr. 3 1999, Energicentret. (in Danish)