Introduction
In this report on an economic investment appraisal of a project we will look at a new house build for a client in a rural area of Ireland. The client has requested that we build an A rated energy efficient house. We will look at the different ways we can build the property. The best materials we can use, and which will suit best. We will look at the type of water systems we can use. Look at the different type of heating systems there are and which system we can install to be cost affective in the long run. We will also look at the different sewage and drainage systems and also look at the electricity installation. we will look at what sort of renewable energy systems we can use. What will be the best insulation we can use along with the doors and windows.
First, we will look at the area the house will be located. The new build will be located about 10 km outside the nearest town on a 1.5-acre site. The site has a stream on one of its boundary’s and farm land on the other 3 sides. Our only access for the site is over the stream so a bridge will need to be installed. A concrete structure will be constructed. As not to interfere with the stream and giving that the stream is lower than the site, concrete hollowcore slabs will be used. The slabs are 1.2 meters wide so 3 will be ordered to use for the bridge, with a safe weight limit of 2 tons which calculates to 19.93 kn. The stream is 2.4 meters wide, so the 3 slabs will be 4 meters in length, so you will have 0.8m over each side of the bank and placed on a foundation build on either side of the stream to help insure against the collapse of the bank or the bridge falling in. A screed of 75mm will be added and a small block wall will be constructed on either side for safety. This way there is no obstruction to water flow with this design and the use of the concrete slabs means that no concrete will be pored over the stream as to not have any pollution issues.
( oranprecast.ie)
The house itself will be a one-story structure of approx. 205 square-meter consisting of a
Kitchen/Dining room – 38 square-metre
Living Room – 49 square-meter
Bedroom 1 – 16 square-meter
Bedroom 2 – 14 square-meter
Bedroom 3 – 9 square-meter
Bedroom 4 – 9 square-meter
Hall –42.55 square-meter
Bathroom – 16 square-meter
Ensuit 1 – 4.5 square-meter
Ensuit 2 – 4 square-meter
Hot-press – 3.06 square-meter
The client wants to use the materials for the main build that will keep in touch with the A-rated seal. So, they have two types to chose from, timber frame or block build. With a timber frame house, the construction time will be shorter than that of a block-built house. But a timber frame house will have to be ordered months before construction starts on site and will also require a hefty deposit, where as with a masonry house all materials can be acquired from the local builder providers. But once on site the timber frame can be installed in as little as a week and first fix of the plumbing and electrics could be started straight away. Block built would be a bit more time consuming and the house would have to be weather proofed before the first fix could start. With energy efficiency there’s not a whole lot of difference between the two ways. It’s all about good design, the specification of insulation, airtightness and good on-site building practices. The timber frame would also feature an outer masonry or brick exterior. Whereas block build will have a twin wall with a cavity of 100mm. (https://www.homebuilding.co.uk/author/mark-brinkley/)
The client in this case prefers a block build house.
The roof will be constructed with timber and a slate tile will be used, the client has chosen a Minislate in the colour of slate blue which has dimensions of 270mm long x 330mm wide, they have a thin leading edge giving a traditional appearance and have a natural slate appearance when laid.
(www.roadstone.ie)
Water supply: This is taking from a public water supply. There is 41m deep borehole situated in Dinantian Pure Bedded Limestones. (Walsh Island PWS, Coolagarry BH) The water in the area is hard water so a filtration system will be required. A Twin Cylinder Water Softener with Duplex Parallel Flow will be installed. With a single cylinder water softener, you will need to know your water usage to determine what size tank you would need. A 10-litre tank would be sufficient for 2 – 3 people, a 17-litre tank will do a family up to 5 people where as a 30- litre tank would be needed for a larger family of 6+. With a twin cylinder system is suitable for all sizes of family’s because while one side is softening the water the other side is waiting on standby until the first side empty’s then switches over to the second side with no interruption, then visa versa. Plus, most single tank water softeners are operated by an electrical control head where the latest twin tank softeners use a water displacement meter which measure down to one drop to make sure of max performance. (www.softwater.ie/compare-systems)
So, to compare the two systems we will calculate the NPV. Discount of 12%. Bag of salt 25 kg €8
(The Water Treatment Centre.ie)
Eco Twin tank Single Tank
Price €753.96 €430
Annual Cost
operating ; maintenance €48 €150
Incomes 0 0
Salvage 0 0
Lifespan 15 Years 15 Years
P/F = P/F = 1/(1+0.12)15 = 0.1827
P/A= P/A= (1+0.12)15-1 = 4.4736
0.12(1+0.12)15 = 0.6568 =6.811
NPV = – Capital costs – (Cash out x P/A) + (Cash in x P/A) + (Residual value x P/F)
We have no annual income here and no salvage value, so we remove them from the formula as it is not needed.
NPV = – Capital costs – (Cash out x P/A)
Eco Twin Cylinder: -753.96-(48×6.811)
-753.96-326.99
=€-1080.95
Single Cylinder: -430-(150×6.811)
-430-1021.65
= €-1451.65
The Eco Twin Cylinder has a less negative value than the Single Cylinder, so the client will purchase the Eco Twin Cylinder Water Softener.
Heating Systems: The client requested underfloor heating throughout the house along with towel radiators in each bathroom. So 100mm of insulation will be laid under the floor with a concrete screed of no more than 75mm will be poured once the pipes are laid. A total of 147.8 m squared of underfloor pipe will be needed. (theunderfloorheatingstore). For the heating system we can install a geothermal system or an oil system. With a BTU of 88,280 needed a 26-kw boiler is needed. Geothermal, with inclusion of 200m² of UFH will cost at least €14k-€18k for a 2,500 sq ft house (SEAI). An air to water heat pump will be installed. An oil-fired system with radiators for this house will cost between €10k-€12k. the annual cost to run a heat pump would be roughly €550 on your energy bill and a service around every 4 years at a cost of €200. With an oil system you would be looking at approximately €1100 a year of oil and a yearly servicing cost of €150. Life span of a heat pump is roughly 20 years. So, we will work out the NVP to see which option is better. Assuming an interest rate of 12% compounded annually.
Air to water Oil
Price €17,000 €12,500
Annual Cost
operating ; maintenance €600 €1250
Incomes 0 0
Salvage 0 0
Lifespan 20 20
P/F = P/F = 1/(1+0.12)20 = 0.1037
P/A= P/A= (1+0.12)20-1 = 8.6463
0.12(1+0.12)20 = 1.1576 =7.469
NPV = – Capital costs – (Cash out x P/A) + (Cash in x P/A) + (Residual value x P/F)
We have no annual income here and no salvage value, so we remove them from the formula as it is not needed.
NPV = – Capital costs – (Cash out x P/A)
Air to water NPV = -17,000-(600×7.469)
-17,000-4481.40
= -€21,481.40
Oil NVP = -12,500-(1250×7.469)
-12,500-9336.25
= -€21,836.25
The Air to Water system has a less negative value than the Oil system so the client will install the Air to Water system.
Sewage treatment: There is no pubic sewer drainage network near site, so a septic tank must be installed.” The Water Services (Amendment) Act 2012 includes registration and inspection arrangements. This means that all on-site septic tank systems or domestic wastewater treatment systems will have to be registered.” (epa.ie)
“So, a Bluestream’s Tri-cel Wastewater Treatment Systems is preferred for this project. This system comprises of 3 treatment zones. In the first zone wastewater fills into the first chamber, the heavier solids settle on the bottom and the lighter solids float to the top, 70% of these solids are removed in the first settlement zone. A baffling system holds the heavier solids in the first chamber and allows wastewater to move into the 2nd chamber (aeration zone).So in the 2nd chamber masses of naturally occurring bacteria are in specially designed plastic filters so when the wastewater from the first chamber flows threw the second chamber threw these filters the bacteria feeds on the waste thus removing them from the liquid. The wastewater is passed through these filters over and over ensuring a very high treatment efficiency. Then the purified liquid is the passed into the 3rd chamber. Before discharge from the system any small quantities of bacteria must be separated from the liquid, this happens in the 3rd chamber as the rate of water is slowed down so any bacteria left can settle to the bottom of the tank as sludge and a return system pumps this sludge back to the first chamber. The remaining treated water now meets the required standard to be safely passed out threw a percolation system into the garden.” (septictanks.ie)
(septictanks.ie)
Electrical supply: An application must be made to the ESB networks to get connected to electricity network. For this an NC2 connection form must be filled out and sent. A 16 kVA capacity should be applied for as it is needed due to the heat pump.
(NC2 Form)
As the site is less that 500m away from a medium voltage network as there are other dwellings in the area a site visit is not needed to be carried out and a quote will be issued in 7 working days once the application is received (NC2 Form)
Solar PV panels will also be installed to help save money on the electricity bill and to generate clean energy. The Irish national average electrical usage is 4,200 kWh, a typical 3-bedroom house. (bonkers.ie national-average-energy-consumption). Output from PV panels varies but we will expect to make savings of 1520 kWh per year. (electricireland.ie/ solar-pv). So, if it cost 18.5c per kwh, a year’s energy bill of 4,200kWh will cost €777, while with the PV panels generating 1520kWh will give you savings of €281 per year.
Windows and Doors: for an A rated home windows with a U-value of 1 and below are needed, there are plenty of companies that offer windows with a U-value of less that 1. For this build we will be purchasing PassiV Aluminium windows from Munster Joinery, these windows will consist of quadruple glazed Krypton gas filled with U-values as low as 0.5W/m2K (munsterjoinery.ie)
Insulation: The house will be insulated to the highest standard, an 50mm Kooltherm K108 Cavity Board will be used in our 100mm wall cavity. On the inner floor under the underfloor pipe we will use 100 mm Thermalon TF70 board. On our inner walls we will use a 55mm Kooltherm K118 Insulated Plasterboard. On the ceilings we will use 32mm Kooltherm K17 insulated plaster board. (Kingspan). We will use 140mm Isover Metac rolls for the attic space. (Isover)
References
• Esb networks nc2 form
• http://oranprecast.ie/images/download/Hollowcore%20Load%20Span%20Tables.pdf
• http://www.epa.ie/water/wastewater/legislation/
• http://www.theunderfloorheatingstore.com/room-calculator
• https://shop.electricireland.ie/products/install-detail/solar-pv
• https://www.bonkers.ie/guides/gas-electricity/national-average-energy-consumption/
• https://www.homebuilding.co.uk/comparing-masonry-and-timber/
• https://www.housing.gov.ie/sites/default/files/migrated-files/en/Publications/DevelopmentandHousing/BuildingStandards/FileDownLoad%2C27316%2Cen.pdf
• https://www.roadstone.ie/products/minislate/
• Isover.ie
• Kingspan.ie
• munsterjoinery.ie
• septictanks.ie/services/wastewater-treatment-systems/
• The Water Treatment Centre.ie
• www.softwater.ie
