In another sign the Reserve Bank of New Zealand is serious about using its new macro-prudential tools to slow riskier lending growth, it has argued the tools would had been very useful if applied during New Zealand's last housing boom, from 2005 to 2008.The RBNZ issued a research paper by economist Chris Hunt on Monday that mapped its new macro-prudential tools on to data on the housing market and banking system from 2005 onwards, in a "counterfactual exercise"."It finds that, with the benefit of hindsight, there would have been a compelling case for macro-prudential intervention from 2005 onwards to address a build-up of systemic risk within the financial sector," Hunt said."The temporary increase in capital or liquidity buffers, or the application of loan-to-value restrictions on residential mortgages, would have materially enhanced the resilience of the financial system in the face of developments late in the decade," he said, adding that they would have tempered house price and lending growth too.The research paper details the surge in lending and asset growth in New Zealand after 2005, and says the bank was too slow to put up interest rates to dampen that growth. Nor did it have any other tools with which to slow that growth.It also details how the RBNZ now uses a quarterly Macro-Prudential Indicators (MPI) report internally. The reports include details on excessive debt levels, asset prices that are over-valued and weak lending standards."In the context of the present counterfactual exercise, the systemic risk assessment implied by our current MPIs would have suggested the need to seriously consider deploying macro-prudential instruments from around 2005 onwards," the RBNZ says. The research paper ignores the debate that the Reserve Bank had publicly with the government from 2005 to 2007 about the use of "supplementary stabilisation instruments", including a mortgage interest levy, to slow mortgage lending growth. In the end, the Reserve Bank chose not to use these tools.