Refurbishment Example 2

8/9/2019 Refurbishment Example 2

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Refurbishment example 2

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Refurbishment example 2 – Office Building with Medium-level Glazing

This case study concerns an office building located on an out-of-town business park. It consists

of mainly cellular of open-plan office space with a small number of meeting rooms. The rooms

are spread over two storeys and the net usable area is 3398m2

. The heating is controlled by athermostat in each open-plan space. n air conditioning system cools the server room and part of

the building. !peration of heating and cooling plant is based on ".## - 22.## each day$ the boiler

efficiency is estimated at "#% and a &'( is fitted but only the basic features are utili)ed.

The energy consumption figures are shown in Table *(+.+$ and may be compared with the

benchmark figures from ,*! +9 in table *(+.2. limited energy audit was carried out on the

building.

The figures show that the performance is better than typical$ but falls short of best practice. Thus$

there is room for some improvements to be made. *loser inspection of the figures shows that the

potential areas of improvement are heating and hot water$ and lighting.

The -values of the elements$ from the original building data$ are as shown below. The /la)ing

0atio 1/0 is #%.

,lement-value

145s6.m.7rea

1s6.m.

1457 % abric eat :oad % Total eat :oad4alls #.8; ;8# ;#3.2 . 2.3/la)ing .< ;8# 2<88.# 3<." + .;0oof #.;9 +<99 832. ++.; ;.8

loor 2 +<99 3398.# ;<.; +9.Σ "32+."

=entilation conductance 1#.33n= +##92.# 8.#

T:* +";+3."

The lighting level throughout the offices is 3## lu> which is an appropriate level for open-plan

offices but is not particularly efficient at 2#45m 2. This gives a total installed wattage of <99<#4$

which$ allowing for a diversity factor of #. gives an annual energy consumption for the lighting

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of 9 +;; k4. !ther electrical use is estimated at 2#k4h5m 25year$ giving an annual total of

<"9<#k4h 1++.;% of total energy use .

The building is located in (cotland where heating degree days ? 2 ## and cooling degree days ?

+#8.

pplying a correction factor of #." for -day week use and #.< for intermittent plant operation$

the annual heating energy consumption ? +";+3 > #." > #.< > #.#2; > 2 ##5#." ?

<"+<;;k4h5year 18#% of total energy use .

llowing for a *!@ of 3.# for air conditioning$ the cooling energy is

+";+3 > #." > #.< > #.#2; > +#853 ? <""#k4h5year 1#.8% of total energy use .

summary of the energy consumption$ percentage of total$ and costs$ is given below.

pplication

*onsumption

% oftotal *ost

% oftotalcost

eating <"+<;; "9.83#223.9

8 <+.8*ooling <""# #.8 ";;." +.

:ighting 9 +;; ++.3+#;< .8

; 2+.;!ther <"9<# 8.+ ";" .< + .3

Total 8;+ +8 +##;89+#.+

2 +##.#

The lighting constitutes over 2#% of the total energy costsA improvements could involve

improved control and5or the use of more efficient tubes and luminaires. (hort-term low cost

measures to improve the lighting could include stickers ne>t to light switches. :onger term

measures re6uiring significant investment involve changing the lighting control strategy to

include occupancy sensing or daylight level sensing$ but it would be more appropriate to

instigate these during a comprehensive lighting replacement programme. The long term strategy

would include an investigation into the costs of such a programme.

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The heat loss from the curtain walling represents only % of the fabric heat load and 2.3% of the

total heating demand$ therefore any improvements are unlikely to prove cost-effective.

reduction of the -value by #%$ resulting in a lowering of the energy consumption by only

2. %$ would save only B+3# per year at a cost of over B ###$ a payback period of over ;# years.

change from single to double gla)ing saves B" # per year but at a payback period of over 2#

years. This could be Custified if there were other reasons for changing the gla)ing$ such as rotting

or corroded frames$ or for purposes of soundproofing. t this particular out-of-town location

sound pollution is not a problem and the latter does not apply. The double gla)ing would have

the further effect of reducing draughts and infiltration$ which constitutes a further heat loss.

Taking this into account would reduce the payback period by another -< years$ but it remains an

unattractive proposition.

Specific Rec mmendati ns

If double gla)ing is not to be implemented$ then some form of draughtstripping would reduce

infiltration$ with a payback of 3-; years.

ddition of Thermostatic 0adiator =alves 1T0= would improve control and heating efficiency

at a cost of B+#-+ per radiator.

rolling programme of installing sub-meters$ paid for from the energy savings.

Investigate the possibility of providing a separating chiller for the server room so that cooling

operation can be optimi)ed.

Install blinds to reduce building cooling load.

!rganise an information campaign to urge staff to turn off e6uipment such as computers$

photocopies and printers at night.

The use of the &'( should be e>tended to includeA

!ptimum se6uencing of boilers.

ight set back for heating.

!ptimum start5stop for heating.

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'a>imum use of outside air for cooling.

:imit basic hours of operation to 9.##-+8.## 'onday- riday and instigate a booking system for

provision of services outside these hours.

(et &'( to log performance and use results for 'onitoring and Targeting.

This would re6uire investment in training the building manager in the use of the &'($ but is

likely to give very 6uick returns.

The long-term strategy should includeA

,stablish a database of energy consumption figures and related records.

Identify the companyDs strategic plans and investment criteria.

,stablish an energy efficiency programme.

,stablish a replacement programme for lighting.

The specific recommendations for improvement$ particularly for heating and cooling$ are highly

dependent on location. If the same building were located in :ondon$ where heating degree days

and cooling degree days are 2+29 and 3< respectively$ the heating load becomes " % 1cost$

% and cooling load 3% 1cost$ .;% of the total. In 0ome$ with heating and cooling degree

days of ++#3 and ++"3 respectively$ the heating load falls further to % 1cost$ 33% while the

cooling load increases to +3.8% 1cost 2#% .

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Summar! f "nerg! # nsumpti n and # sts$

pplicatio

n

*onsumpti

on

% of

total *ost % of total cost

,dinburg

h

eating <"+<;; "9.83#223.9

8 <+.8*ooling <""# #.8 ";;." +.

:ighting 9 +;; ++.3+#;< .8

; 2+.;!ther <"9<# 8.+ ";" .< + .3

Total 8;+ +8;89+#.+

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pplication

*onsumption

% oftotal *ost % of total cost :ondon

eating "+9"2 " .2 "38."

; ."*ooling 228"3 3.# 2 +<.#3 .;

:ighting 9 +;; +2.<+#;< .8

; 22."!ther <"9<# 9.# ";" .< +<.2

Total " "9;9;<+9<.2

+

pplication

*onsumption

% oftotal *ost % of total cost 0ome

eating 29<23; .<+333#.

3 33.9*ooling "3 #8 +3.8 8#8 .88 2#.

:ighting 9 +;; +".9+#;< .8

; 2<.<!ther <"9<# +2.8 ";" .< +9.#

Total 328;<393 ".8

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Refurbishment Example 2

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