The paper presents a model of a reference wind farm. The model considers the wind and wave climatologies for a specific site from which two different wind farm layouts are derived. These layouts are examined through the effective wakeenhanced turbulence intensity at the hub height for a given climatology, and a simple model for the influence on capital expenditures is proposed. An electrical design is presented, the cable losses are calculated and the energy yield is determined. An operation and maintenance model is established, and the associated operating expenditure is obtained. All of the models are then summarized in terms of a levelized cost of energy using a numerical simulation tool, which allows the layouts to be compared. The data and models are freely available online for others to use and may serve as a baseline for benchmarking and allow researchers to compare and discuss their results.Throughout Europe, 74 offshore wind farms are now installed with a cumulative total installed capacity of 8 GW. 1 The most active development area in Europe is the North Sea, representing 63% of the offshore capacity. The installed offshore capacity is expected to reach 23.5 GW by 2020. 2 Reducing the cost of energy requires that new technological concepts or solutions be investigated. A common reference wind farm (RWF) is useful for quantifying the benefits of one solution over another; that is, a system-level model of a large-scale offshore installation with multi-megawatt turbines containing the relevant data and models is required to represent a wind farm and determine the associated energy costs.Offshore wind farms are complex systems affected by both the environment (e.g. wind, waves, current and seabed) and the design characteristics of the installed equipment (e.g. the turbine type, cabling and distance to shore). These aspects govern the capital and operating expenditures, which, along with the energy produced, determine the energy costs. The components of a RWF model can largely be found in the literature, and thus, the RWF can be based on well-established knowledge. The aerodynamic part includes static wakes, as discussed in, 3,4 and. 5 Added turbulence is modelled in, for instance, 6,7 and, 8 and the last reference established the draft norm in. 9 The power yield for wind farms was investigated in, 10 and commercial software tools are available for this task such as WASP. Operation and maintenance (O&M) aspects for wind farms comprise a substantial part of the costs. 11 In general, the literature has focused on the physical/technical aspects of wind farms, not on the costs involved. For example, the added turbulence in farms is modelled in, 9 but the results regarding the effects of added turbulence on cost are not readily available. 12 Considering this gap in the literature, The Norwegian Centre for Offshore Wind Energy (NORCOWE) has designed an offshore RWF, which is intended to represent the next generation of wind farms to be constructed in the North Sea. The RWF is a baseline for benchmarking and will ...