Diary Entry No.23 - How much did it cost?

Actual Contract cost of building the Crawfordsburn Passivhaus

One of the most commonly asked questions around Passivhaus is the cost. The Crawfordsburn Passive house was constructed at a time of recession and was a competitive contract price. The building was also 'value engineered' before it when to tender so that there were no additional costly items that were not required.

The dwelling has total area of 220.6sqm/2375sqft. The figures below are a breakdown of the construction costs, including site works, building envelope and fixtures and fittings.

External Works

Drainage - £7,000

Siteworks including paving, water trap, and lawns - £4,000

Excavation, oversite, reduced levels, foundation trenches and disposal - £980

Trenches for Mains Water supply and NIE supply - £3,000

Substructure

Concrete in Foundations - £5,154

Ground Floor Construction to include: Screed, insulation, subfloor, 200mm Platinum EPS Floor insulation, foam glass perinsul SL - £6,550

Superstructure

Timber Frame Construction to include: External walls: U-Value of 0.11 W/(m2K) or below. To include breathable membrane, Insulated panels; vapour/airtight membrane and to include all airtightness seals/tapes Upper Floor: eco joists @400cc to incorporate services.

Roof: U-Value of 0.13W/(m2K) or below. Internal Walls (load bearing and non load bearing) Cavity Wall Ties: suitable for timber framed structures with 50mm cavity Fixing: all nails, screws and fixings Additional: 8mm plywood backing behind plasterboard -£56,000

External Outer-Leaf Construction to include:100mm concrete blockwork - £6,972

External Walls Finish to include: 10mm first undercoat, 20mm top coat, 2 coats of paint -£5,420

Windows (including Velux) and external doors - £11,220

Roof

Roof construction to include: Natural slate, Ridge tiles, Dormer roofs (zinc) - £9,221

External Zinc - £2,850

Roof drainage - £1,200

External Porch and Balcony Construction      

External Porch to include: Roof construction, foundations, steel support, timber slats, flange channels, lead flashings - £2,950

External Juliet Balconies to include: Toughened glass and fixings -£1,000

Internal Finishes

Plastered internal walls and ceilings -£8,200

Internal painting -£3,000

Internal screen - £240

Internal Joinery

Staircase and internal Balconies - £4,100

Doors and frames - £5,000

Ironmongery - £500

Skirting, window boards -£1,300

Floor finishes - £2,600

Internal bookcase - £1,400

Services and Fittings

Bathroom Fittings - £200

Electrical installation - £4,200

Mechanical Ventilation Heat Recovery (MVHR) - £6,500

Plumbing and Heating Installation to include heat pump, solar panels and wood burning stove - £13,683

Costs Summary

Subtotal - £174,440

Other associated costs (preliminaries, insurance, warranties) - £17,560

Total construction cost - £192,000

 

Cost comparison - Passivhaus v Standard Construction

This cost comparison exercise between Passivhaus Standard and house constructed to the minimum standard SAP 2009.

The Crawfordsburn passive house is to be 221spm. We have calculated the construction costs of an equivalent ‘typically constructed’ dwelling of a similar size, 221sqm, for comparison.

Cost is undeniably the main factor in any build. This is the limitation which determines what can be afforded, and what cannot. It is interesting for us to list the costs of our passive house, but it is useless if we have nothing to compare it too.

Total construction costs broken down into building element

Passivhaus compared to SAP 2009

Foundations

£5,154 - £3,747

Ground floor construction

£6,550 - £7,231

Timber SIP Frame- standard 'stick' built timber frame and insulation

£56,000 -£44,800

External windows and doors

£11,220 - £10,125

External envelope

£28,613 - £29,613

Plumbing and heating installation

£13,683 - £600

Ventilation

£6,500 - £1,000

Internal finishes

£27,540 - £21,640

Electrical

£4,200 - £4,200

Prelims/insurances/site-works etc

£32,540 - £44,513

Total construction costs compared

£192,000.00 - £175,969.00

 

Additional cost of building a Passivhaus compared to a typical dwelling build to current building regulation

The cost of the Crawfordsburn passive house dwelling is 8.3% more expensive than the ‘typically constructed to SAP 2009’ dwelling. The difference in construction costs is £16,031.

While this passive house cost more to construct its running costs are significantly lower. We need to gain an understanding of how quickly the construction cost difference will be regained through utility bill savings.

Keeping domestic energy bills under control is a continual battle, with energy suppliers constantly announcing price increases (energy prices have increased by over 30% over the past three years, 17.8% in this year alone). Electricity and home heating oil are typically used to fuel houses in Northern Ireland (85% of households). This innovative passive house employs a variety of techniques to fuel itself.

We have carried out exact calculations to compare the running costs of the Passivhaus with those of a conventional home. In the first year of occupation the running costs of the Passivhaus will be £414.62, considerably less than £1391.95 for a conventional dwelling. Taking into consideration the inevitable price increases the costs of running the Passivhaus are actually a minimum of 70% lower.

Payback period for Passivhaus standard

Tor the purposes of his exercise we have assumed a yearly running costs (taking into account 10% yearly electricity increase which has a compounding effect upon the larger running cost)

By year 10 our client will have gained cumulative amount of £15,575.97 in energy bill differences.

Therefore the difference of the construction cost will be regained in 10.2 years. The overall building efficiency, interior comfort levels and innovative design ensures that the Passivhaus delivers many advantages over typical construction.