The clustering properties of a well-defined sample of 734 Hα emitters at z= 0.845 ± 0.015, obtained as part of the Hi-z Emission Line Survey, are investigated. The spatial correlation function of these Hα emitters is very well described by the power-law ξ = (r/r₀)^-1.8, with a real-space correlation, r₀, of 2.7 ± 0.3 h^-1 Mpc. The correlation length r₀ increases strongly with Hα luminosity (L_Hα), from r₀ ∼ 2 h^-1 Mpc for the most quiescent galaxies [star formation rates (SFRs) of ∼4 M_⊙ yr^-1] up to r₀ > 5 h^-1 Mpc for the brightest galaxies in Hα. The correlation length also increases with increasing rest-frame K-band (M_K) luminosity, but the r₀-L_Hα correlation maintains its full statistical significance at fixed M_K. At z = 0.84, star-forming galaxies classified as irregulars or mergers are much more clustered than discs and non-mergers, respectively; however, once the samples are matched in L_Hα and M_K, the differences vanish, implying that the clustering is independent of morphological type at z ∼ 1 just as in the local Universe. The typical Hα emitters found at z = 0.84 reside in dark matter haloes of ≈10¹² M_⊙, but those with the highest SFRs reside in more massive haloes of ≈10¹³ M_⊙. The results are compared with those of Hα surveys at different redshifts: although the break of the Hα luminosity function L*_Hα evolves by a factor of ∼30 from z= 0.24 to 2.23, if the Hα luminosities at each redshift are scaled by L*_Hα(z) then the correlation lengths indicate that, independently of cosmic time, galaxies with the same (L_Hα)/L*_Hα(z) are found in dark matter haloes of similar masses. This not only confirms that the star formation efficiency in high redshift haloes is higher than locally but also suggests a fundamental connection between the strong negative evolution of L*_Hα since z = 2.23 and the quenching of star formation in galaxies residing within dark matter haloes significantly more massive than 10¹² M_⊙ at any given epoch.