In 2019, our article highlighted why the NEC4 contract was a good fit for the pharmaceuticals industry: NEC4:  Good Fit for Pharmaceuticals



Palm Commercial Services are Silver Members of the NEC Users Group.  The NEC Users' Group is an international community of NEC users, with more than 450 members, representing and connecting organisations from across the supply chain.

Palm Commercial Services can offer advice with regards to how the Schedule of Cost Components shall be used.  Palm Commercial Services can ensure that the clause 31 programme contains sufficient information to ensure that it is accepted.  Palm Commercial Services has experience in working on disputes involving the NEC3 contract and can help with advice and management throughout the dispute resolution process (adjudication, arbitration, etc.)


The NEC3 and NEC4 conditions of contract facilitates recovery of additional costs associated with weather in an objective way. Firstly, the party has to calculate if and how much of the adverse weather occurring in each calendar month is a Compensation Event. A Compensation Event occurs when a weather measurement is recorded that exceeds the average 1 in 10 year value. It is only the difference between the actual and average 1 in 10 year value that is used in the assessment of the Compensation Event. The NEC3 conditions of contract sets out how the difference should be calculated. Once it has been calculated that a Compensation Event has occured its effect on the programme and any entitlement to additional time and money is assessed.

Does the adverse weather event constitute a Compensation Event?

The NEC3 and NEC4 core clauses are identical for weather Compensation Events and set out Compensation Events at clause 60.1. The Compensation Event for weather is defined at clause 60.1(13) as occurring when:

“(13) A weather measurement is recorded

  • within a calendar month,

  • ​before the Completion Date for the whole of the works and

  • at the place stated in the Contract Data

the value of which, by comparison with the weather data, is shown to occur on average less frequently than once in ten years.

Only the difference between the weather measurement and the weather which the weather data show to occur on average less frequently than once in ten years is taken into account in assessing a compensation event."

It is only the difference between the actual weather recorded and the average 1 in 10 year value that is considered when assessing the Compensation Event.

The NEC3 and NEC4 conditions of contract explains how the difference is calculated.

Weather Data 

The Contract Data, if properly completed, will state which weather station the historical weather data is to be taken from and which weather service is to provide the data (for example the Met Office or Meteo Group). The weather data should be obtained from the weather service and weather station that are defined in the Contract Data.

The NEC3 Guidance Notes explain that the provisions for weather in the ECC were developed in consultation with the Met Office so it would be difficult for anyone to disagree with the Met Office’s method of calculating the average 1 in 10 year value.


Weather Measurements Recorded (The actual weather during each calendar month of the project)


The Contract Data sets out the weather measurements that are to be recorded during the project and specifies the location where the recordings are to be taken. The default weather measurements are:


“The cumulative rainfall (mm)

The number of days with rainfall more than 5 mm

The number of days with minimum air temperature less than 0 degrees Celsius

The number of days with snow lying at …. Hours GMT”

Several weather services provide monthly summary sheets that show, for each of the default weather measurements, the amount recorded during that particular month of the project and the average 1 in 10 year figure. From this weather service, a comparison of figures is established to determine if a Compensation Event has occurred during the calendar month.

If the recorded weather during the calendar month is not worse than the average 1 in 10 year value then, in that case, there is no Compensation Event. 


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Palm Commercial Services Ltd, 32 Coppice View Road, Sutton Coldfield, West Midlands. B73 6UE.  United Kingdom.

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