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Sensitivity Analysis
Given the outlined limitations with regard to data availability and assumptions, the research here also puts a
large emphasis on conducting sensitivity analysis. In this regard, a number of scenarios were analysed which
reflected the need to test different elements. The following areas where included in consideration:
Main Analysis - Construction and Acquisition Costs
As outlined through this section, due to relatively low levels of output in recent years, the central costs for both
construction and acquisition units are based on units delivered between 2016 and 2017, tendered/delivered projects for
2018 and cost guidelines set by DHPLG. To reflect the lack of comprehensive cost data, the analysis here provides
sensitivity around the estimates of +/- 10%, ensuring that an appropriate range of costs are tested.
Main Analysis - Housing Market Scenarios
As listed above, under the central scenario real house prices increase in line with ESRI projections from 2018 to 2021,
ESRI long term projections from 2021 to 2025 and then by 2% per annum. For sensitivity analysis, a low scenario (80% of
ESRI projections to 2025 and 0.5% beyond) and a high scenario (120% of ESRI projections to 2025 and 3.5% beyond
were tested to reflect the significant uncertainty around long term housing market projections.
Additional Analysis - Time Horizon
While the central analysis analysed and assessed costs over a 20 year period, a period of 30 years was also examined to
assess the impact of considering longer time periods. To complete this analysis, the same methodology was used as above
with a number of differences. Firstly, the renewal cost for constructed and acquired houses for year 30 is €25,000 based
on estimates provided by DHPLG. Secondly, for long term leasing arrangements it is assumed that a renewed agreement
is entered into in year 20 and that the same initial costs apply across the mechanism. Finally, AHB CALF leases are not
assessed given that the loans are tied to the length of the lease which is typically no longer than 20 years.
Additional Analysis - Maintenance and Renewal Costs
It has been noted that detailed data on maintenance/renewal costs was not available and that the average cost across
all LAs based on NOAC data and the DHPLG’s estimate of renewal costs have been utilised. The previous research by the
Housing Agency assumed that the maintenance costs equated to 1% of the construction/acquisition cost and that the
cost of renewal was €52,000
. Sensitivity analysis was carried out to use these same assumptions and assess the impact.
Additional Analysis - Leasing and RAS Costs
For the monthly costs of each of the leasing mechanism and RAS, the average cost as of Q4 2017 was utilised within the
central analysis. However, it is the case that this average cost is a mix of all tenancies active under each of the schemes
potentially reflecting a range of times when leases were entered into. As such, sensitivity analysis has been undertaken
using the average rent for 2 and 3 bed units in each LA area based on both RTB data and Daft.ie data. To estimate the
cost of each mechanism, it is assumed that each achieves the target discount (as outlined previously).
Additional Analysis – Residual Value
A residual value for units delivered through construction/acquisition has been included at 66% of market value and
additional analysis was undertaken with scenarios of 33%, 50% and 75% to assess the impact. It should be noted that a
Tenant (Incremental) Purchase Scheme is in place which allows LA tenants in certain circumstances to purchase the unit
that they are living in at a discount with that discount being maintained where the tenant continues to live in the unit
over time The scheme allows for purchases at between 40-60% of market price reflecting a residual value similar to the
scenarios included here.
To reflect this sensitivity analysis within the presentation of the results the following approach is taken. Firstly,
within the main analysis a central estimate based on the outlined methodology for each delivery mechanism
Estimate was for 2008 and adjusted for inflation to 2017.