The Cost of Building to the nearly-Zero Energy Building Standard: A Financial Case Study

Abstract

The EU has mandated that all buildings are built to the nearly-Zero Energy Buildings (nZEB) standard from 2020. The Passivhaus standard has been in existence for over 25 years and potentially offers a tried and tested method of achieving nZEB, but can it be used as a cost-effective means of achieving nZEB?

This paper analyses the cost differential of building dwellings located in the south-east of Ireland to the nZEB standard using the passive house methodology, in comparison to building to the current prevailing minimum building regulations. A comparison of the two standards is also made to determine the suitability of using the passive house standard as a means of achieving nZEB compliance. In the analysis, the extra cost (compared with building to the minimum building regulations) include increased airtightness, insulation levels, a heat recovery and ventilation system and higher performing windows and doors. Cost reductions are achieved in the elimination of the traditional heating system, chimney stack and reduced site overheads. Costs are based on a designated date for the works of 1 January 2017, exclude VAT at the prevailing standard and reduced rates, exclude cost of site purchase, and exclude any design team or professional fees arising.

The costs are compared on an element-by-element basis using the National Standard Building Elements and Design Cost Control Procedures [1] National standard building elements and design cost control procedures. ISBN-13:978-1850531647 edn. Environmental Research Unit) format for comparison, the accepted industry standard in the Republic of Ireland for subdividing the overall cost of construction into logical and defined cost headings, and are assembled in order of the sequence of construction. The comparison shows that while differences exist in individual elements, the overall cost differential between constructing a residential dwelling to current building regs and that of Passivhaus standard is just +€131 excluding VAT. It is noted that while this specific analysis has been carried out on the basis of a case study, it is proposed that the analysis will be of general applicability given the similarities in the large cost items between those mandated by the building regulations and those required in order to achieve the passive house standard (such as insulation levels).