Lighting  »  Lamps

The city administration of Frankfurt has developed a standard refurbishment solution for class-rooms which is on one side about 70% more efficient and on the other hand has a pay-back time of about 5-10 years. Excrepts taken from Bretzke (2006).

The City of Frankfurt am Main made some efforts to reduce the electricity for lighting at schools. The work shows that optimised lighting in classrooms saves both investment cost and variable costs compared to a standard lighting system approach used by the City until this point. "In the last years, the producers have made remarkable progress with the efficiency of lighting. There are to notice conspicuous longer life time, better efficiency, changeable light distribution and therefore at all better planning factors. But those increases in efficiency needs stronger consideration, both, in standards and guidelines as well as in the concrete planning."  The standard solution that was used until this time was 8 luminaires with 58 W T8, resulting in a installed power value of 8.8 W/m².

In the search for a better solution, the new lighting system was tested in pilot-projects at a number of different schools. The specific wattage of the optimised lighting in pilot classrooms was eight T5 35W luminaires which leads to an installed power of 6.1 W/m² or about 2 W/(m^² and 100lx). In the comprehensive school “Schule am Ried”, the illuminance was calculated with an average illuminance of 368 lx. Despite of this optimised planning an even higher average illuminance Em (average illuminance level) of 443 lx was measured after modernisation. When comparing this pilot project with the standard solution used in these school settings, the power consumption was reduced by one third, when compared with the pre-modernization lighting system, the power savings even amount to about 70%. With an optimised planning the costs for investment, maintenance and electricity consumption can be reduced in comparison to a standard new system. Compared to the existing lighting at the school, the new system would provide a pay back time of only 5 to 10 years.

In addition to the optimised planning of lighting, also the daylight use and the occupancy dependent light circuit could be optimised. At the time the pilot project was made, automatic daylight systems have not been economically for application in schools with measured utilization periods between 400 and 1000 h/a. Therefore, a central tracing disconnection was tested and used in the pilot schools. The report stated that "it was shown to be as affective as an automatic control. Five minutes after end of the first school hour (approx. 8:30 am) for the first time in all classes the light is centrally and briefly switched of, beside of inner classrooms. Even in the winter at this time it is already sufficiently bright. But the classes are able to restart the light again if necessary. The switch off is repeated in each break over the day till dawn. Surprisingly in the project there was no negative feedback to this tracing circuit. In relation to an automatic control, the light is completely switched off if not necessary".

The master plan for efficient lighting at UNAM shows the strategy, the total investment costs and the benefits from a systematic refurbishment of the lighting system at UNAM. The pay-back time of the investment would be less than 5 years. Excrepts taken from Büro Ö-quadrat & CSCP (2009).

The master plan for a better lighting at UNAM establishes the broad, strategic principles that should be followed for the lighting system renovation and gives an estimation of the necessary budget and energy and maintenance cost savings that can be achieved. In drawing up the master plan, a dozen UNAM buildings were analysed and lighting use patterns were monitored in each of the buildings. Four typical lighting situations were identified:

• Lighting in foyers and corridors, both those on the outside and those towards the middle of the building (without incident daylight)
• Libraries
• Seminar rooms and class rooms in which lectures are held
• The offices of the university departments and the administration

For each lighting situation, an efficient lighting system was designed and both
the investment costs and the savings in electricity costs were calculated. 
As shown in the figure below, the profitability of the lighting upgrade differs relative to location and lighting use patterns. To calculate the basic payback period, neither the interest rate on the loans nor the expected electricity price increase were taken into account.

Modernisation schedule

It was assumed that the modernisation work will begin in those areas where savings were greater relative to the amount of money invested. This meant almost all foyers and corridors in the UNAM buildings. The payback period for these areas is less than two years (see figure below). In the first year, the lighting in all foyers and corridors would be replaced. In year two, work would start-ed on one quarter of the libraries and over a period of four years some 100 of UNAM’s 130 libraries would receive new lighting.
In year four, the seminar rooms are tackled with work stretching over four years. In the sixth and seventh years, new lighting is installed in all offices.

Costs and Benefits
The next step involves calculating the investment-related costs and the annual operational savings that will be reinvested into the project (see figure below).

The total investment from the first to the seventh year amounts to US$ 13.9 million. During the same period, some US$ 13.7 million in energy and maintenance cost savings flow back to the investor.
 New lighting in the foyers and corridors requires an investment of US$ 760,000 in the first year. This is for a large part offset by annual savings on electricity costs of US$ 444,000 (which does not take into account the fact that a portion of the savings in energy costs cannot be achieved at this stage because the investment occurs over the entire year, meaning that the energy savings are not achieved for the whole year).

In year two, US$ 1.7 million is invested in new lighting for the libraries. The savings on electricity costs arising from the installation of new lighting in the foyers, corridors and some of the libraries amount to US$ 0.92 million in this year alone. A further US$ 1.7 million is invested in another 25 libraries during year three and another US$ 2.9 million in year four is invested in libraries and seminar rooms. At this stage of the project, the investment can largely be covered by the savings on energy costs (this in-cludes expenditure that would otherwise have occurred for regular maintenance work). Hence, in return for an initial investment of US$ 3 million, the savings on energy costs accrued over the lifecycle of the new lighting systems (20 years) amount to US$ 68 million.
After deducting the overall investment of US$ 13.9 million after 7 years, net returns of US$ 54 million are achieved on an initial investment of just US$ 3 million.

Barriers for efficient lighting retrofit
There is no better investment to mitigate climate change with lower risks and higher profits as the lighting refurbishment at UNAM - but there are also some barriers which prevent a prompt solution. UNAM is, unfortunately, also an example for the many barriers to energy-efficient lighting. There is no better investment opportunity with lower risks than the lighting refurbishment at UNAM. Nevertheless it is not guaranteed that such a profitable project will be undertaken, since there are many barriers that have to be overcome:

• The electricity costs for UNAM are paid by government. If UNAM attains savings, the government has to pay less for electricity. However there is no direct incentive for savings on the part of UNAM.
• The departments, institutes and administrative buildings at UNAM are not equipped with individual electricity meters. Despite the fact that the university uses 70 million kWh of electricity each year, there were only two meters on the entire campus in the year 2009.
• Electricity is seen as a free resource from the users of the university: it apparently costs nothing and there is no way to trace its usage.
• If the institutes and departments were to invest in lighting, they would not conduct a feasibility study in relation to the electricity costs over the lifecycle of the lighting system. They would be more likely to decide in favour of the solution involving the lowest investment costs because they do not have to bear the costs of the electricity. With this approach, the cheap solution for the institute becomes an expensive one for the society.
• There is no financial incentive for the decision makers and the permanent employees of the UNAM to invest in efficient lighting. Business as usual is simply the easiest option and makes less work and stress.
• There is not enough staff with the knowledge and skills required for a successful energy efficient building renovation.
• UNAM has no budget for the investment (even if it is profitable).